WO2024255412A1 - Spiro heterocyclic compound and use thereof - Google Patents

Abstract

Disclosed in the present invention are a spiro heterocyclic compound having a structure as shown in formula (I), or a pharmaceutically acceptable salt thereof, a stereoisomer thereof, a deuterated compound thereof or a prodrug molecule thereof, and the use thereof. The compound has the effect of antagonizing MC4 receptor activity, can be used for treating various diseases associated with MC4 receptors, and has great application value.

Description

Spiro heterocyclic compounds and their applications Technical Field

The present invention relates to the technical field of chemical medicine, and in particular to a spiro heterocyclic compound and application thereof.

Background Art

Melanocortin receptors (MCR) are involved in regulating a variety of physiological behaviors of organisms, including energy balance, pigmentation, inflammation, cardiovascular and cerebrovascular function, feeding, sebaceous gland fat secretion, etc. MCR is a subfamily of G-protein coupled receptors (GPCR) with seven transmembrane structures. Five subtypes of melanocortin receptors are known, namely MC1R, MC2R, MC3R, MC4R and MC5R. MC3R is mainly expressed in the central nervous system and regulates energy balance. MC4R is widely expressed throughout the central nervous system and is also expressed in peripheral tissues, such as adipose tissue, where it is involved in regulating feeding behavior and energy expenditure. Other members are mainly expressed in the periphery and are involved in regulating pigmentation (MC1R), adrenal function (MC2R), immune function (MC1R/MC3R) and sebaceous gland activity (MC5R) (Endocr Rev. 2010 Aug; 31(4):506-43).

MC4R is a family A G protein-coupled receptor (GPCR) regulated by endogenous MC4R agonists and inverse agonist/antagonist peptides. Its signaling has physiological effects in regulating energy homeostasis, cachexia, cardiovascular function, glycolipid homeostasis, reproductive and sexual function, brain inflammation and anxiety. Inhibition or antagonism of MC4R signaling leads to increased appetite and food intake (Endocr Rev. 2010 Aug; 31(4): 506-43).

So far, a variety of small molecule MC4R antagonists have been reported, which can reverse or prevent appetite and weight loss in preclinical models of cancer, chronic kidney disease, age-related cachexia or anorexia (Biochim. Biophys. Acta. Mol. Basis. Dis. 2017, 1863 (10), 2414–2435; PLoS One 2009, 4 (3), e4774; J. Med. Chem. 2004, 47 (7), 1602-1604). A recent study reported that a MC4R antagonist peptide (TCMCB07) was effective in cachexia models after oral or subcutaneous administration, which improved appetite to a certain extent and increased weight. It has now entered Phase 1 clinical trials (J Clin Invest. 2020 Sep 1; 130 (9): 4921-4934). In addition, Pfizer has reported a small molecule MC4R antagonist PF-07258669, which has a strong therapeutic effect on the cachexia model of elderly rats and has entered clinical trials (J Med Chem. 2023 Mar 9; 66(5): 3195-3211; patent WO2021250541A1).

Cachexia is a devastating, multifactorial wasting syndrome characterized by loss of homeostatic control of energy and protein balance, involuntary weight loss, and loss of skeletal muscle mass. Cachexia is highly associated with mortality from multiple malignant cancers (e.g., pancreatic, esophageal, gastric, lung, liver, and colorectal cancers, which account for approximately half of cancer deaths worldwide) (Nat Rev Dis Primers. 2018 Jan 18;4:17105; http://www.who.int/mediacentre/factsheets/fs297/en/) and is also associated with further exacerbation of chronic non-malignant diseases. (For example, heart failure, kidney disease, chronic obstructive pulmonary disease, nervous system diseases, AIDS and rheumatoid arthritis, etc.) (Lancet Oncol. 12, 489–495 (2011)). There is currently no effective treatment for cachexia. In addition, it has been observed that when patients with chronic kidney disease (CKD) have more muscle or fat, better appetite, and eat more, they live longer (J Cachexia Sarcopenia Muscle. 2011; 2(1): 9–25).

In view of the important role of melanocortin-4 receptor (MC4R) in the above diseases, the development of efficient and safe MC4R antagonists has great application value for preventing or treating various diseases related to MC4R.

Summary of the invention

Based on this, the present invention provides a class of spiro heterocyclic compounds, which have the effect of antagonizing the activity of MC4 receptors and can be used to treat various diseases related to MC4 receptors.

The present invention includes the following technical solutions.

A spiroheterocyclic compound having a structure represented by formula (I) or a pharmaceutically acceptable salt thereof or a stereoisomer thereof or a deuterated product thereof or a prodrug molecule thereof:

in:

R ₁ , R ₂ , R ₃ and R ₄ are independently selected from the group consisting of H, deuterium, C ₁ -C ₆ alkyl, C ₁ -C ₆ deuterated alkyl, C ₂ -C ₆ alkenyl, C ₂ -C ₆ alkynyl, C ₃ -C ₈ cycloalkyl, halogen-substituted C ₃ -C ₈ cycloalkyl, C ₃ -C ₈ cycloalkylmethyl, halogen, halogen-substituted C ₁ -C ₆ alkyl, hydroxy, hydroxy-substituted C ₁ -C ₆ alkyl, C ₁ -C ₆ alkoxy-substituted C ₁ -C ₆ alkyl, cyano, -OR, -N(R) ₂ , -SR, -C(O)OR, -C(O)N(R) ₂ , -C(O)R, -S(O)R, -S(O) ₂ R, -S(O) ₂ N(R) ₂ , -N(R)C(O)R;

R is selected from the group consisting of: H, C ₁ -C ₆ alkyl, C ₂ -C ₆ alkenyl, C ₂ -C ₆ alkynyl, C ₃ -C ₈ cycloalkyl, C ₃ -C ₈ cycloalkylmethyl, halogen-substituted C ₁ -C ₆ alkyl, hydroxy-substituted C ₁ -C ₆ alkyl, alkoxy-substituted C ₁ -C ₆ alkyl, amino-substituted C ₁ -C ₆ alkyl, alkylamino-substituted C ₁ -C ₆ alkyl;

R ₅ and R ₆ are independently selected from: H, deuterium, halogen;

M is selected from: CH, N;

W is selected from: O, S, NR ₇ ;

Q is selected from the group consisting of: CR ₇ R ₈ , NR ₈ , C═O, O, S, or absent;

_R7 and _R8 are independently selected from the group consisting of: H, deuterium, halogen, _C1 - _C6 alkyl, _C1 - _C6 deuterated alkyl, C2 _{- C6} alkenyl, _C2 - _C6 Alkynyl, C ₃ -C ₈ cycloalkyl, halogen-substituted C ₁ -C ₆ alkyl, halogen-substituted C ₃ -C ₈ cycloalkyl, hydroxy, cyano, amino, C ₁ -C ₆ alkylamino; or R ₈ and the substituents in A are linked to form a substituted or unsubstituted 5-7 membered carbocyclic or heterocyclic ring;

A is selected from: C ₆ -C ₁₀ membered aryl substituted or unsubstituted by R ₉ and R ₁₀ , 5-10 membered heteroaryl substituted or _{unsubstituted} by R ₉ and R 10, 7-10 membered benzoheterocyclyl substituted or unsubstituted by R ₉ and R ₁₀ ;

Each _R9 and _R10 is independently selected from the group consisting of H, deuterium, halogen, _C1 - _{C6 alkyl} , _C1 - _C6 deuterated alkyl, _{C2 - C6} alkenyl, _C2 - _C6 alkynyl, _cyano , _C3 - _C8 cycloalkyl, _C3 - _C8 deuterated cycloalkyl, C3- _C8 cycloalkylC1- _C6 alkyl, _{C1 -} C6 alkylsulfonyl, C1- _{C6 alkylthio, C1-C6 deuterated alkylthio, C3-C8 cycloalkylthio , halogen} -substituted C1 _{- C6} alkyl, _C1 - _C6 alkoxy, _C1 - _C6 deuterated alkoxy, halogen-substituted C1 _{- C6} alkoxy, _{C3 - C8} cycloalkyloxy, _{C3-C8 deuterated} cycloalkyloxy, halogen-substituted _C3 -C6 ₈ -cycloalkyloxy, carbamoyl;

_A1 is selected from: phenyl substituted or unsubstituted by _R11 and _R12 , 5-6 membered heteroaryl substituted or unsubstituted by _R11 and _R12 ;

Each of R ₁₁ and R ₁₂ is independently selected from the group consisting of: H, deuterium, halogen, C ₁ -C ₆ alkyl, C ₁ -C ₆ deuterated alkyl, C ₃ -C ₈ cycloalkyl, halogen-substituted C ₁ -C ₆ alkyl, cyano, and C ₁ -C ₆ alkoxy.

In some embodiments, A is selected from: naphthyl substituted or unsubstituted by R ₉ and R ₁₀ , 9-10 membered heteroaryl substituted or unsubstituted by R ₉ and R ₁₀ , 9-10 membered benzoheterocyclyl substituted or unsubstituted by R ₉ and R ₁₀ .

In some embodiments, A is selected from:

Among them: the dotted line in the ring represents whether it is a C-C single bond or not;

X ₁ , X ₂ , and X ₃ are independently selected from the group consisting of CR ₉ , N.

In some embodiments, A is selected from:

In some embodiments, A is selected from: W is O.

In some embodiments, each R ₉ and R ₁₀ is independently selected from the group consisting of H, deuterium, halogen, C ₁ -C ₃ alkyl, C ₁ -C ₃ deuterated alkyl, C ₂ -C ₃ alkenyl, C ₂ -C ₃ alkynyl, cyano, C _{3 -C 6 cycloalkyl, C 3 -C 6 deuterated} cycloalkyl, C ₃ -C ₆ cycloalkylmethyl, C ₁ -C ₃ alkylsulfonyl, C ₁ -C ₃ alkylthio, C ₁ -C ₃ deuterated alkylthio, C ₃ -C ₆ cycloalkylthio, halogen-substituted C ₁ -C ₃ alkyl, C ₁ -C ₃ alkoxy, C ₁ -C ₃ deuterated alkoxy, halogen-substituted C ₁ -C ₃ alkoxy, C ₃ -C ₆ cycloalkyloxy, C ₃ -C ₆ deuterated cycloalkyloxy, halogen-substituted C ₃ -C ₆ -cycloalkyloxy, carbamoyl.

In some embodiments, each R ₉ and R ₁₀ is independently selected from the group consisting of hydrogen, methoxy, fluorine, difluoromethyl, difluoromethoxy, cyano, methyl, ethynyl, carbamoyl, methylsulfonyl, cyclopropyloxy, methylthio, and chlorine.

In some embodiments, A is selected from:

In some embodiments, each R ₁₁ and R ₁₂ is independently selected from the group consisting of: H, deuterium, halogen, C ₁ -C ₃ alkyl, C ₁ -C ₃ deuterated alkyl, C ₃ -C ₆ cycloalkyl, halogen-substituted C ₁ -C ₃ alkyl, cyano, and C ₁ -C ₃ alkoxy.

In some embodiments, _A1 is selected from:

In some embodiments, _A1 is selected from:

In some embodiments, W is selected from: O, S, NH, NCH ₃ .

In some embodiments, W is selected from: S, NR ₇ ;

Wherein, _R7 in W is selected from the group consisting of: H, _C1 - _C6 alkyl, _C1 - _C6 deuterated alkyl, _C3 - _C8 cycloalkyl, halogen-substituted C1 _{- C6} alkyl, and halogen-substituted _C3 - _C8 cycloalkyl.

In some embodiments, _R7 and _R8 are independently selected from: H, deuterium, halogen, _C1 - _C3 alkyl, _C1 - _C3 deuterated alkyl, _C2 - _C3 alkenyl, _C2 -C3 alkynyl, _C3 - _C6 cycloalkyl, _{halogen-substituted C1-C3 alkyl, halogen-substituted C3-C6 cycloalkyl , hydroxyl} , cyano, amino, _{C1 - C3} alkylamino; or _R8 and the substituents in A are connected to form a substituted or unsubstituted 5-6 membered carbocyclic or heterocyclic ring.

In some embodiments, _R7 and _R8 are independently selected from: H, deuterium, methyl, hydroxyl, cyano, vinyl, ethynyl, amino, deuterated methyl, or _R8 and the substituent in A are connected to form a 5-6 membered carbocyclic or heterocyclic ring.

In some embodiments, Q is selected from: -N(CH ₃ )-,

In some embodiments, R ₄ is selected from: C ₁ -C ₆ alkyl, C ₁ -C ₆ deuterated alkyl, halogen-substituted C ₁ -C ₆ alkyl.

In some embodiments, R ₁ , R ₂ , R ₃ and R ₄ are independently selected from the group consisting of: H, deuterium, C ₁ -C ₃ alkyl, C ₁ -C ₃ deuterated alkyl, C ₂ -C ₄ alkenyl, C ₂ -C ₄ alkynyl, C ₃ -C ₆ cycloalkyl, halogen-substituted C ₃ -C ₆ cycloalkyl, C ₃ -C ₆ cycloalkylmethyl, halogen, halogen-substituted C ₁ -C ₃ alkyl, OH, hydroxy-substituted C ₁ -C ₃ alkyl, alkoxy-substituted C ₁ -C ₃ alkyl, and cyano.

In some embodiments, R ₁ is selected from: methyl, hydroxy, difluoromethyl, trifluoromethyl, cyano, chlorine, fluorine, vinyl, ethynyl, cyclopropyl, deuterated methyl.

In some embodiments, R ₂ is selected from: H, fluorine, methyl, chlorine, deuterium.

In some embodiments, R ₃ is selected from: H, fluorine.

In some embodiments, R ₄ is selected from: H, methyl, methoxymethyl, monofluoromethyl.

In some embodiments, the spiro heterocyclic compound is selected from the following compounds:

The present invention also provides the use of the spiroheterocyclic compound or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or its prodrug molecule, including the following technical solutions.

The use of the spiroheterocyclic compound or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or its prodrug molecule in the preparation of MC4 receptor antagonist.

Use of the spiroheterocyclic compound or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or its prodrug molecule in the preparation of a drug for preventing and/or treating diseases and/or symptoms associated with the MC4 receptor.

In some of these embodiments, the diseases and/or symptoms associated with the MC4 receptor are selected from: diseases and/or symptoms associated with the MC4 receptor are selected from: cachexia (including cachexia associated with chronic diseases, cancer, acquired immune deficiency syndrome (AIDS), heart failure, chronic kidney disease (CKD) and the like); anorexia or anorexia nervosa (such as senile anorexia, anorexia associated with chemotherapy and radiotherapy); nausea; vomiting; weight loss (involuntary weight loss); sarcopenia; muscle atrophy; muscle weakness; weakness; bone diseases (such as bone loss); pain or neuropathic pain; anxiety (such as post-traumatic stress disorder, PTSD, etc.); sexual dysfunction; and inflammatory diseases (such as inflammatory diseases associated with cachexia, anorexia, sarcopenia, etc.), etc.

The present invention also provides a pharmaceutical composition for preventing and/or treating diseases and/or symptoms associated with MC4 receptor, including the following technical solutions.

A pharmaceutical composition for preventing and/or treating diseases and/or symptoms associated with MC4 receptors, comprising an active ingredient and a pharmaceutically acceptable excipient and/or carrier, wherein the active ingredient comprises the spiroheterocyclic compound or a pharmaceutically acceptable salt thereof or a stereoisomer thereof or a deuterated product thereof or a prodrug molecule thereof.

The present invention also provides a method for preventing and/or treating diseases and/or symptoms associated with MC4 receptors, the method comprising: administering a safe and effective amount of the spiroheterocyclic compound of the present invention or a pharmaceutically acceptable salt thereof or a stereoisomer thereof or a deuterated substance thereof or a prodrug molecule thereof; and/or,

Administer a safe and effective amount of the pharmaceutical composition of the present invention.

The present invention has the following beneficial effects:

The spiroheterocyclic compound provided by the present invention or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or The prodrug molecule has the effect of antagonizing the activity of MC4 receptor and can be used to treat various diseases related to MC4 receptor, which has great application value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a plasma drug-dose curve of Compound 100, Compound 104 and PF07258669 after oral administration to mice.

FIG2 is a drug-time curve of the brain tissue of Compound 100, Compound 104 and PF07258669 after oral administration to mice.

DETAILED DESCRIPTION

In the compounds described herein, when any variable (e.g., R, etc.) occurs more than once in any component, its definition at each occurrence is independent of the definition at every other occurrence. Likewise, combinations of substituents and variables are permitted as long as such combinations render the compound stable. Lines drawn from substituents into the ring system indicate that the indicated bond may be attached to any substitutable ring atom. If the ring system is polycyclic, it means that such bonds are attached only to any appropriate carbon atom of the adjacent ring. It is to be understood that one of ordinary skill in the art may select substituents and substitution patterns for the compounds of the invention to provide chemically stable compounds that can be readily synthesized from readily available raw materials by techniques in the art and the methods set forth below. If a substituent itself is substituted with more than one group, it is to be understood that these groups may be on the same carbon atom or on different carbon atoms as long as the structure is stable.

The term "alkyl" as used herein is intended to include branched and straight chain saturated aliphatic hydrocarbon groups having a specific number of carbon atoms. For example, the definition of "C ₁ -C ₆ alkyl" includes groups having 1, 2, 3, 4 _{, 5 or 6 carbon atoms in a straight or branched arrangement. For example, "C 1 -C 6 alkyl " specifically} includes methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, isobutyl, pentyl, hexyl.

The term "cycloalkyl" refers to a monocyclic saturated aliphatic hydrocarbon group having a specific number of carbon atoms. For example, "cycloalkyl" includes cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl, etc.

The term "alkoxy" refers to a group in which an alkyl group is directly linked to oxygen, i.e., a group having an -O _{- alkyl} structure, such as _-OCH3 , _-OCH2CH3 , _-OCH2CH2CH3 , _-O - _CH2CH ( _{CH3 ) 2 , -OCH2CH2CH2CH3} , _-O -CH( _CH3 ) ₂ , and the like.

The term "heterocyclyl" is a saturated or partially unsaturated monocyclic or polycyclic cyclic substituent (acyclic, bridged or spirocyclic) in which one or more ring atoms are selected from N, O or S(O)m (wherein m is an integer from 0 to 2) as a heteroatom, and the remaining ring atoms are carbon, for example: morpholinyl, piperidinyl, tetrahydropyrrolyl, pyrrolidinyl, dihydroimidazolyl, dihydroisoxazolyl, dihydroisothiazolyl, dihydrooxadiazolyl, dihydrooxazolyl, dihydropyrazinyl, dihydropyrazolyl, dihydropyridinyl, dihydropyrimidinyl, dihydropyrrolyl, dihydrotetrazolyl, dihydrothiadiazolyl, dihydrothiazolyl, dihydrothiophenyl, dihydrotriazolyl, dihydroazetidinyl, tetrahydrofuranyl, tetrahydrothiophenyl and the like, and N-oxides thereof. The attachment of the heterocyclic substituent may be achieved through a carbon atom or through a heteroatom.

The term "heteroaryl" refers to an aromatic ring containing one or more heteroatoms selected from O, N or S. Aryl includes, but is not limited to, quinolyl, pyrazolyl, pyrrolyl, thienyl, furanyl, pyridinyl, pyrimidinyl, pyrazinyl, triazolyl, imidazolyl, oxazolyl, isoxazolyl, pyridazinyl, benzofuranyl, benzothiophenyl, benzoxazole, indolyl, and the like; "heteroaryl" is also understood to include the N-oxide derivative of any heteroaryl containing nitrogen.

The term "substituted" refers to the replacement of hydrogen radicals in a particular structure with the radical of a specified substituent.

As will be appreciated by those skilled in the art, "halo" or "halo" as used herein refers to chlorine, fluorine, bromine and iodine.

Unless otherwise defined, alkyl, cycloalkyl, aryl, heteroaryl and heterocycloalkyl substituents may be unsubstituted or substituted. For example, C1-C6 alkyl may be substituted with one, two or three substituents selected from OH, halogen, alkoxy, dialkylamino or heterocyclic radicals such as morpholinyl, piperidinyl, etc.

The present invention includes free forms of compounds of formula I, as well as pharmaceutically acceptable salts and stereoisomers thereof. Some specific exemplary compounds of the present invention are amine compounds in non-salt form, i.e., "free forms". Pharmaceutically acceptable salts of the present invention can be synthesized from compounds of the present invention containing a basic or acidic moiety by conventional chemical methods. Typically, salts of basic compounds are prepared by ion exchange chromatography or by reacting a free base with a stoichiometric amount or excess of an inorganic or organic acid in the desired salt form in an appropriate solvent or a combination of multiple solvents. Similarly, salts of acidic compounds are formed by reacting with an appropriate inorganic or organic base.

Therefore, the pharmaceutically acceptable salts of the compounds of this invention include conventional non-toxic salts of the compounds of this invention formed by reacting alkaline compounds of this invention with inorganic or organic acids. For example, conventional non-toxic salts include salts derived from inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, sulfamic acid, phosphoric acid, nitric acid, etc., and also include salts prepared from organic acids such as acetic acid, propionic acid, succinic acid, glycolic acid, stearic acid, lactic acid, malic acid, tartaric acid, citric acid, ascorbic acid, pamoic acid, maleic acid, hydroxymaleic acid, phenylacetic acid, glutamic acid, benzoic acid, salicylic acid, p-aminobenzenesulfonic acid, 2-acetoxy-benzoic acid, fumaric acid, toluenesulfonic acid, methanesulfonic acid, ethanedisulfonic acid, oxalic acid, isethionic acid, trifluoroacetic acid, etc.

If the compound of the present invention is acidic, then suitable "pharmaceutically acceptable salts" refer to salts prepared from pharmaceutically acceptable non-toxic bases including inorganic bases and organic bases. Salts derived from inorganic bases include aluminum salts, ammonium salts, calcium salts, copper salts, iron salts, ferrous salts, lithium salts, magnesium salts, manganic salts, manganous salts, potassium salts, sodium salts, zinc salts, etc. Ammonium salts, calcium salts, magnesium salts, potassium salts and sodium salts are particularly preferred. Salts derived from pharmaceutically acceptable organic non-toxic bases, including salts of primary, secondary and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines and basic ion exchange resins such as arginine, betaine, caffeine, choline, N,N'-dibenzylethylenediamine, diethylamine, 2-diethylaminoethanol, 2-dimethylaminoethanol, aminoethanol, ethanolamine, ethylenediamine, N-ethylmorpholine, N-ethylpiperidine, glucosamine, glucosamine, histidine, hydroxocobalamin, isopropylamine, lysine, methylglucamine, morpholine, piperazine, piperidine, guaiac, polyamine resins, procaine, purine, theobromine, triethylamine, trimethylamine, tripropylamine, tromethamine and the like.

Berg et al., "Pharmaceutical Salts," J. Pharm. Sci. '1977: 66: 1-19, describes in more detail the preparation of the above-mentioned pharmaceutically acceptable salts and other typical pharmaceutically acceptable salts.

The stereoisomers of the present invention are, i.e. (depending on their structure) as enantiomers, diastereomers, syn-/anti-isomers, cis-/trans-isomers, epimers and (E)-/(Z)-isomers. The compounds of formula I can be used in the context of the present invention in the form of pure stereoisomers or in the form of any mixture of stereoisomers, in the latter case the racemates are preferred.

The metabolites of the compounds involved in the present invention and their pharmaceutically acceptable salts, as well as prodrugs that can be converted into the structures of the compounds involved in the present invention and their pharmaceutically acceptable salts in vivo, are also included in the claims of the present invention.

The present invention also provides a pharmaceutical composition for preventing and/or treating diseases and/or symptoms associated with MC4 receptors, which comprises an active ingredient within a safe and effective amount range and a pharmaceutically acceptable adjuvant.

The "active ingredient" described in the present invention refers to the compound of formula I described in the present invention, or its stereoisomer, or its pharmaceutically acceptable salt, or its solvate, or its prodrug molecule, or its deuteride, or its tritiated product.

"Safe and effective amount" means that the amount of active ingredient is sufficient to significantly improve the condition without causing serious side effects.

When using the pharmaceutical composition, a safe and effective amount of the compound of the present invention is applied to a mammal (such as a human) in need of treatment, wherein the dosage during administration is a pharmaceutically effective dosage, and for a person weighing 60 kg, the daily dosage is usually 1 to 2000 mg, preferably 20 to 500 mg. Of course, the specific dosage should also take into account factors such as the route of administration and the health status of the patient, which are all within the skill of a skilled physician.

"Pharmaceutically acceptable excipients" refer to: one or more compatible solid or liquid fillers or gel substances, which are suitable for human use and must be sufficiently pure and sufficiently low in toxicity.

"Compatibility" herein means that the components in the composition can be blended with the active ingredient of the present invention and with each other without significantly reducing the efficacy of the active ingredient.

Examples of pharmaceutically acceptable excipients include cellulose and its derivatives (such as sodium carboxymethyl cellulose, sodium ethyl cellulose, cellulose acetate, etc.), gelatin, talc, solid lubricants (such as stearic acid, magnesium stearate), calcium sulfate, vegetable oils (such as soybean oil, sesame oil, peanut oil, olive oil, etc.), polyols (such as propylene glycol, glycerol, mannitol, sorbitol, etc.), emulsifiers (such as ), wetting agents (such as sodium lauryl sulfate), colorants, flavoring agents, stabilizers, antioxidants, preservatives, pyrogen-free water, etc.

In another preferred embodiment, the compound of formula I of the present invention can form a complex with a macromolecular compound or a polymer through a non-bonding reaction. In another preferred embodiment, the compound of formula I of the present invention as a small molecule can also be connected to a macromolecular compound or a polymer through a chemical bond. The macromolecular compound can be a biological macromolecule such as a high polysaccharide, protein, nucleic acid, polypeptide, etc.

There is no particular limitation on the administration of the active ingredient or pharmaceutical composition of the present invention. Representative administration methods include (but are not limited to): oral, intratumoral, rectal, parenteral (intravenous, intramuscular or subcutaneous), etc.

Solid dosage forms for oral administration include capsules, tablets, pills, powders and granules.

In these solid dosage forms, the active ingredient is mixed with at least one conventional inert excipient (or carrier), such as sodium citrate or Dicalcium phosphate, or in combination with:

(a) fillers or extenders, for example, starch, lactose, sucrose, glucose, mannitol and silicic acid;

(b) binders, for example, hydroxymethylcellulose, alginate, gelatin, polyvinyl pyrrolidone, sucrose and gum arabic;

(c) humectants, for example, glycerin;

(d) disintegrants, for example, agar, calcium carbonate, potato or tapioca starch, alginic acid, certain complex silicates, and sodium carbonate;

(e) a buffering solvent, such as paraffin;

(f) absorption accelerators, for example, quaternary ammonium compounds;

(g) wetting agents, such as cetyl alcohol and glyceryl monostearate;

(h) adsorbents, for example, kaolin; and

(i) Lubricants, for example, talc, calcium stearate, magnesium stearate, solid polyethylene glycol, sodium lauryl sulfate, or mixtures thereof. In capsules, tablets and pills, the dosage form may also contain a buffering agent.

The solid dosage forms can also be prepared using coatings and shell materials, such as enteric coatings and other materials known in the art. They can contain opacifying agents, and the release of the active ingredient in such compositions can be delayed in a certain part of the digestive tract. Examples of embedding components that can be used are polymeric substances and waxes.

Liquid dosage forms for oral administration include pharmaceutically acceptable emulsions, solutions, suspensions, syrups or tinctures. In addition to the active ingredient, the liquid dosage form may contain inert diluents conventionally used in the art, such as water or other solvents, solubilizers and emulsifiers, for example, ethanol, isopropanol, ethyl carbonate, ethyl acetate, propylene glycol, 1,3-butylene glycol, dimethylformamide and oils, in particular cottonseed oil, peanut oil, corn germ oil, olive oil, castor oil and sesame oil or mixtures of these substances. In addition to these inert diluents, the composition may also contain adjuvants, such as wetting agents, emulsifiers and suspending agents, sweeteners, flavoring agents and spices.

In addition to the active ingredients, suspensions may contain suspending agents such as, for example, ethoxylated isostearyl alcohols, polyoxyethylene sorbitol and sorbitan esters, microcrystalline cellulose, aluminum methanol and agar, or mixtures of these substances.

Compositions for parenteral injection may include physiologically acceptable sterile aqueous or anhydrous solutions, dispersions, suspensions or emulsions, and sterile powders for reconstitution into sterile injectable solutions or dispersions. Suitable aqueous and non-aqueous carriers, diluents, solvents or excipients include water, ethanol, polyols and suitable mixtures thereof.

Synthetic Methods: In addition to standard methods known in the literature or exemplified in the experimental procedures, the methods in the following synthetic schemes (Schemes 1-5) can be used to prepare the compounds of the present invention. In conjunction with the following synthetic schemes, the compounds and synthetic methods described in the present invention can be better understood. The synthetic schemes described describe methods that can be used to prepare the compounds described in the present invention. The described methods are merely illustrative scheme descriptions for illustrative purposes and do not constitute an endorsement of the present invention. Limitation of scope.

Solution 1

Solution 2

Option 3

Option 4

Option 5

Example 1: Preparation of (S)-N-(5-fluoro-2-methoxypyridin-4-yl)-N,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxamide (Compound 1) (Prepared according to Scheme 1 and 2)

Step 1a: Preparation of 1-benzyl-3-((trimethylsilyl)ethynyl)pyrrolidin-3-ol (Compound 0102-1): Under nitrogen protection, n-butyl lithium (25.11 ml, 62.78 mmol, 1.1 eq) was added dropwise to a solution of ethynyltrimethylsilane (6.73 g, 68.48 mmol, 1.2 eq) in tetrahydrofuran (50 ml) at -70°C, and the mixture was stirred at -70°C for 1.0 hour. Then, a solution of 1-benzylpyrrolidin-3-one (Compound 0101-1) (10.0 g, 57.07 mmol, 1.0 eq) in tetrahydrofuran (20 ml) was added dropwise to the reaction solution at -60°C, the cryogenic device was removed, and the mixture was stirred at room temperature overnight. The reaction solution was quenched with ammonium chloride solution and extracted with ethyl acetate, and the organic phase was dried and concentrated under reduced pressure. The residue was purified by silica gel column (petroleum ether/ethyl acetate=5/1 to 3/1) to give yellow oily product 1-benzyl-3-((trimethylsilyl)ethynyl)pyrrolidin-3-ol (12.11 g, yield: 77.63%).

Step 1b: Preparation of 1-benzyl-3-ethynylpyrrolidin-3-ol (Compound 0103-1): Under nitrogen protection, potassium carbonate (12.24 g, 88.72 mmol, 2.0 eq.) was added to a solution of 1-benzyl-3-((trimethylsilyl)ethynyl)pyrrolidin-3-ol (0102-1) (12.11 g, 44.36 mmol, 1.0 eq.) in methanol (100 ml), and the mixture was stirred at room temperature for 1.5 hours. The solvent was removed under reduced pressure, the residue was diluted with water and extracted with ethyl acetate, and the organic phase was dried and concentrated under reduced pressure. The residue was purified by silica gel column (ethyl acetate) to obtain a yellow oily product 1-benzyl-3-ethynylpyrrolidin-3-ol (7.65 g, yield: 85.68%).

Step 1c: Preparation of 1-benzyl-3-ethynylpyrrolidin-3-yl acetate (Compound 0104-1): Under nitrogen protection, acetyl chloride (5.08 g, 64.7 mmol, 1.0 equiv) was added to a solution of 1-benzyl-3-ethynylpyrrolidin-3-ol (0103-1) (7.65 g, 38.05 mmol, 1.0 equiv) and N,N-diisopropylethylamine (9.82 g, 76.1 mmol, 2.0 equiv) in dichloromethane (100 ml) at 0°C. The mixture was stirred at 0°C for 0.5 hours. The reaction solution was quenched with water and extracted with dichloromethane. The organic phase was dried and concentrated under reduced pressure. The residue was purified by silica gel column (petroleum ether/ethyl acetate = 4/1 to 1/1) to obtain a yellow oily product 1-benzyl-3-ethynylpyrrolidin-3-yl acetate (8.94 g, yield: 96.70%).

Step 1d: Preparation of 1-benzyl-3-ethynyl-N-(4-methoxybenzyl)pyrrolidin-3-amine (Compound 0105-1): Under nitrogen protection, a solution of 1-benzyl-3-ethynylpyrrolidin-3-yl acetate (0104-1) (8.92 g, 36.66 mmol, 1.0 eq.) in tetrahydrofuran (18 ml) was added to a solution of 4-methoxybenzylamine (10.06 g, 73.32 mmol, 2.0 eq.) and cuprous chloride (363 mg, 3.67 mmol, 0.1 eq.) in tetrahydrofuran (60 ml) at 70° C., and the mixture was stirred at 70° C. for 20 minutes. The reaction solution was diluted with water and extracted with ethyl acetate, and the organic phase was dried and concentrated under reduced pressure. The residue was purified by silica gel column (petroleum ether/ethyl acetate = 4/1 to 1/1) to obtain a yellow oily product 1-benzyl-3-ethynyl-N-(4-methoxybenzyl)pyrrolidin-3-amine (3.5 g, yield: 29.83%). LCMS (ESI): m/z = 321 [M+1] ⁺ .

Step 1e: Preparation of 2-chloro-3-iodo-6-methylpyridine (Compound 0107-1): To a mixture of 2-chloro-6-methylpyridin-3-amine (0106-1) (25.0 g, 175.33 mmol, 1.0 eq) in 6M dilute hydrochloric acid (175 ml) was added dropwise a solution of sodium nitrite (14.52 g, 210.39 mmol, 1.2 eq) in water (50 ml) at 0°C. The mixture was stirred at 0°C for 0.5 h. A solution of potassium iodide (58.18 g, 350.46 mmol, 2.0 eq) in water (100 ml) was added dropwise. The mixture was warmed to room temperature and then stirred overnight. 2M sodium hydroxide solution was slowly added to adjust pH=8, and then the aqueous layer was extracted with ethyl acetate (100 ml×2). The combined organic layers were washed with saturated brine (100 ml×1), dried over anhydrous sodium sulfate and concentrated. The residue was subjected to column chromatography on silica gel (petroleum ether: ethyl acetate = 60: 1 to 10: 1) to give a pale yellow solid 2-chloro-3-iodo-6-methylpyridine (37.67 g, yield: 85%). LCMS (ESI): m/z 254 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 20: 1).

Step 1f: Preparation of 1-benzyl-3-((2-chloro-6-methylpyridin-3-yl)ethynyl)-N-(4-methoxybenzyl)pyrrolidin-3-amine (Compound 0108-1): To a mixture of 2-chloro-3-iodo-6-methylpyridine (0107-1) (35.78 g, 141.43 mmol, 1.0 eq), bistriphenylphosphine palladium dichloride (4.96 g, 7.1 mmol, 0.05 eq) and cuprous iodide (1.35 g, 7.1 mmol, 0.05 eq) in triethylamine (220 ml) was added 1-benzyl-3-ethynyl-N-(4-methoxybenzyl)pyrrolidin-3-amine (0105-1) (45.25 g, 141.43 mmol, 1.0 eq). The mixture was stirred at 80° C. overnight under nitrogen atmosphere. The solvent was removed under reduced pressure. The residue was separated by column chromatography on silica gel (petroleum ether: ethyl acetate = 10: 1 to 1: 2) to give a brown oily substance 1-benzyl-3-((2-chloro-6-methylpyridin-3-yl)ethynyl)-N-(4-methoxybenzyl)pyrrolidin-3-amine (54.66 g, yield: 87%). LCMS (ESI): m/z 446 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 2: 1).

Step 1g: Preparation of 1-benzyl-3-(2-(2-chloro-6-methylpyridin-3-yl)ethyl)-N-(4-methoxybenzyl)pyrrolidin-3-amine (Compound 0109-1): Platinum dioxide (4.17 g, 18.38 mmol, 0.15 eq) was added to a mixture of 1-benzyl-3-((2-chloro-6-methylpyridin-3-yl)ethynyl)-N-(4-methoxybenzyl)pyrrolidin-3-amine (0108-1) (54.66 g, 122.56 mmol, 1.0 eq) in methanol (300 ml). The mixture was stirred at room temperature under hydrogen balloon pressure for 10 hours. The mixture was filtered. The filtrate was concentrated under reduced pressure to give a brown oily substance: 1-benzyl-3-(2-(2-chloro-6-methylpyridin-3-yl)ethyl)-N-(4-methoxybenzyl)pyrrolidine-3-yl Amine (53.5 g, crude product). LCMS (ESI): m/z 450 [M+1] ⁺ ; TLC: Rf 0.3 (petroleum ether:ethyl acetate=2:1).

Step 1h: Preparation of 1-benzyl-1'-(4-methoxybenzyl)-7'-methyl-3',4'-dihydro-1'H-spiro(pyrrolidine-3,2'-[1,8]naphthyridine (Compound 0110-1): To a mixture of 1-benzyl-3-(2-(2-chloro-6-methylpyridin-3-yl)ethyl)-N-(4-methoxybenzyl)pyrrolidin-3-amine (0109-1) (42.18 g, 93.94 mmol, 1.0 eq), palladium acetate (1.05 g, 4.70 mmol, 0.05 eq) and RuPhos (4.38 g, 1.0 mmol, 0.1 eq) in dioxane (420 ml) was added sodium tert-butoxide (18.04 g, 1 87.88 mmol, 2.0 eq.). The mixture was heated to 115°C under a nitrogen atmosphere and reacted overnight. The solvent was removed under reduced pressure. The residue was diluted with water (200 ml). The aqueous layer was extracted with ethyl acetate (150 ml×3). The combined organic layer was washed with saturated brine (100 ml×1), dried over anhydrous sodium sulfate and concentrated. The residue was subjected to column chromatography on silica gel (petroleum ether: ethyl acetate = 20:1 to 5:1) to give a light yellow solid 1-benzyl-1'-(4-methoxybenzyl)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] (21.0 g, yield: 54%). LCMS (ESI): m/z 414 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 5:1).

Step 1i: Preparation of 1-benzyl-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] (Compound 0111-1): To a mixture of 1-benzyl-1'-(4-methoxybenzyl)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] (0110-1) (21.0 g, 50.85 mmol, 1.0 equiv) in dichloromethane (150 mL) was added dropwise trifluoroacetic acid (57.98 g, 508.5 mmol, 10.0 equiv) at 0°C. The mixture was warmed to room temperature and stirred for 6 hours. The solvent was removed under reduced pressure. The mixture was diluted with water (200 mL). Solid sodium carbonate was added to adjust pH=10, and then the aqueous layer was extracted with dichloromethane (100 ml×3). The combined organic layer was washed with saturated brine (100 ml×1), dried over anhydrous sodium sulfate and concentrated. The residue was subjected to column chromatography on silica gel (dichloromethane: methanol=80:1 to 20:1) to obtain a pale yellow oily substance 1-benzyl-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] (14.9 g, yield: 100%). LCMS (ESI): m/z 294 [M+1] ⁺ ; TLC: Rf 0.5 (dichloromethane: methanol=20:1).

Step 1j: Preparation of tert-butyl 7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (Compound 0112-1): Palladium hydroxide/carbon (10%, 3.73 g) was added to a mixture of 1-benzyl-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] (0111-1) (14.9 g, 50.85 mmol, 1.0 equiv) and di-tert-butyl dicarbonate (22.2 g, 101.7 mmol, 2.0 equiv) in tetrahydrofuran (150 ml). The mixture was heated to 60°C under hydrogen balloon pressure for 40 hours. The mixture was filtered. The filtrate was concentrated under reduced pressure. The residue was subjected to column chromatography on silica gel (dichloromethane: ethyl acetate 10: 1 to 1: 1) to give (S)-tert-butyl 7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (13.5 g, yield: 87%) as a pale yellow solid. LCMS (ESI): m/z 305 [M+1] ⁺ ; TLC: Rf 0.5 (dichloromethane: ethyl acetate = 1: 1).

Step 1k: Preparation of (S)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (Compound 0113-1) and (R)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (0114-1): The enantiomers of 7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (0112-1) were separated by supercritical fluid chromatography (chromatographic column: ChiralPak IC, 250×30 mm ID, 10 μm; mobile phase: A is carbon dioxide, B is ethanol; eluent: 30% B; flow rate: 150 ml/min; back pressure: 100 bar; column temperature: 38°C). The first eluting enantiomer is (R)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (compound 0114-1) (6.32 g, yield: 47%), and the second eluting enantiomer is (S)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (compound 0113-1) (6.29 g, yield: 47%). Analytical conditions (chromatographic column: ChiralPak IC, 100×4.6 mm ID, 3 μm; mobile phase: A is carbon dioxide, B is ethanol (0.05% diethylamine); eluent: 40% B; flow rate: 2.5 ml/min; back pressure: 100 bar; column temperature: 35°C)

Step 11: Preparation of (S)-6'-bromo-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (Compound 0116-1): To a mixture of (S)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (0113-1) (6.29 g, 20.76 mmol, 1.0 eq) in dichloromethane (60 mL) was added dibromohydantoin (2.97 g, 10.38 mmol, 0.5 eq) at 0°C. The mixture was stirred at 0°C for 1 hour. Saturated aqueous sodium sulfite solution (50 mL) was added to quench the reaction. The aqueous layer was extracted with dichloromethane (50 mL×3). The combined organic layers were washed with saturated brine (50 mL x 1), dried over anhydrous sodium sulfate and concentrated to give a pale yellow solid (S)-6'-bromo-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (7.74 g, yield: 98%). LCMS (ESI): m/z 382 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether:ethyl acetate=3:1).

Step 1m: Preparation of (S)-(1-(tert-Butyloxycarbonyl)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-6'-yl)boronic acid (Compound 0118-1): to (S)-6'-bromo-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (0116-1) (5.75 g, 15.05 mmol, 1.0 equiv), Xphos-Pd-G2 (237 mg, 0.30 mmol, 0.02 eq.), Xphos (215 mg, 0.45 mmol, 0.03 eq.), potassium acetate (3.69 g, 37.63 mmol, 2.5 eq.) and sodium tert-butoxide (36 mg, 0.38 mmol, 0.025 eq.) were added to a mixture of methanol (60 ml) and ethylene glycol (6 ml). Tetrahydroxydiboron (3.37 g, 37.63 mmol, 2.5 eq.) was added. Under nitrogen atmosphere, the mixture was stirred at 53°C overnight. The solvent was removed under reduced pressure. The residue was diluted with water (50 ml). 2M sodium hydroxide solution was added to adjust pH = 12, and then the mixture was washed with methyl tert-butyl ether (30 ml × 3). 2M dilute hydrochloric acid solution was added to the aqueous layer to adjust pH = 8, and then extracted with ethyl acetate (50 ml × 3). The combined organic layer was washed with saturated brine (30 mL x 1), dried over anhydrous sodium sulfate and concentrated to give a white solid (S)-(1-(tert-butyloxycarbonyl)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-6'-yl)boronic acid (3.58 g, yield: 69%). LCMS (ESI): m/z 348 [M+1] ⁺ ; TLC: Rf 0.3 (dichloromethane:methanol=10:1).

Step 1n: Preparation of (S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (Compound 0120-1): To (S)-(1-(tert-butyloxycarbonyl)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-6'-yl)boronic acid (0118-1) (3.58 g, 10. 31 mmol, 1.0 eq.), Xphos-Pd-G2 (243 mg, 0.31 mmol, 0.03 eq.), Xphos (147 mg, 0.31 mmol, 0.03 eq.) and sodium carbonate (3.28 g, 30.93 mmol, 3.0 eq.) were added to a mixture of toluene (25 ml), ethanol (25 ml) and water (10 ml). 2-Bromopyrimidine (1.80 g, 11.34 mmol, 1.1 eq.) was added. The mixture was stirred at 55 °C overnight under nitrogen atmosphere. The solvent was removed under reduced pressure. The residue was washed with water (50 The mixture was diluted with ethyl acetate (30 ml × 3) and then extracted with ethyl acetate (30 ml × 3). The combined organic layer was washed with saturated brine (20 ml × 1), dried over anhydrous sodium sulfate and concentrated. The residue was subjected to column chromatography on silica gel (petroleum ether: ethyl acetate = 4: 1 to 1: 1) to give a white solid (S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (2.94 g, yield: 75%). LCMS (ESI): m/z 382 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 1: 1).

Step 1o: Preparation of (S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (Intermediate 0122-1): A mixture of (S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (0120-1) (1.07 g, 3.08 mmol, 1.0 eq) in methanolic hydrogen chloride solution (4M solution, 10 ml) was stirred at room temperature for 3.5 hours. The solvent was removed under reduced pressure. The residue was dried under vacuum to give (S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (1.09 g, crude) as a pale yellow solid. LCMS (ESI): m/z 282 [M+1] ⁺ ; TLC: Rf 0.3 (dichloromethane:methanol=10:1).

Step 1p: Preparation of 5-fluoro-4-iodo-2-methoxypyridine (Compound 0202-1): To a mixture of 2,5-difluoro-4-iodopyridine (Compound 0201-1) (25.0 g, 103.74 mmol, 1.0 eq.) in methanol (70 ml) was added sodium methoxide (5.4 M in methanol, 57.6 ml, 311.23 mmol, 3.0 eq.) at 0°C. The mixture was heated to 60°C under nitrogen atmosphere and stirred for 1.5 hours. The solvent was removed under reduced pressure. The residue was diluted with saturated ammonium chloride solution (150 ml) and then extracted with ethyl acetate (70 ml x 3). The combined organic layers were washed with saturated brine (100 ml x 1), dried over anhydrous sodium sulfate and concentrated. The residue was separated by column chromatography on silica gel (petroleum ether: ethyl acetate = 50: 1) to give 5-fluoro-4-iodo-2-methoxypyridine (22.06 g, yield: 84%) as a white solid. LCMS (ESI): m/z 254 [M+1] ⁺ ; TLC: Rf 0.6 (petroleum ether: ethyl acetate = 20: 1).

Step 1q: Preparation of 5-fluoro-2-methoxy-N-(4-methoxybenzyl)-N-methylpyridin-4-amine (compound 0203-1): To a mixture of 5-fluoro-4-iodo-2-methoxypyridine (0202-1) (1.0 g, 3.95 mmol, 1.0 eq), tris(dibenzylideneacetone)palladium (109 mg, 0.119 mmol, 0.03 eq), RuPhos (111 mg, 0.237 mmol, 0.06 eq) and sodium tert-butoxide (1.14 g, 11.85 mmol, 3.0 eq) in toluene (15 ml) was added 1-(4-methoxyphenyl)-N-methylmethanamine (0.72 g, 4.74 mmol, 1.2 eq). The mixture was heated to 120° C. under nitrogen atmosphere and stirred overnight. The solvent was removed under reduced pressure. The residue was subjected to column chromatography on silica gel (petroleum ether: ethyl acetate = 30: 1 to 10: 1) to give 5-fluoro-2-methoxy-N-(4-methoxybenzyl)-N-methylpyridin-4-amine (630 mg, yield: 58%) as a pale yellow oil. LCMS (ESI): m/z 277 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 10: 1).

Step 1r: Preparation of 5-fluoro-2-methoxy-N-methylpyridin-4-amine (Compound 0204-1): To a mixture of 5-fluoro-2-methoxy-N-(4-methoxybenzyl)-N-methylpyridin-4-amine (0203-1) (630 mg, 2.28 mmol, 1.0 eq.) in dichloromethane (12 ml) was added trifluoroacetic acid (3 ml). The mixture was stirred at room temperature for 2 hours. The solvent was removed under reduced pressure. The residue was diluted with water (30 ml). Solid sodium bicarbonate was added to adjust pH=8, and then the aqueous layer was extracted with ethyl acetate (15 ml×3). The combined organic layers were washed with saturated brine (20 ml×1), dried over anhydrous sodium sulfate and concentrated to give 5-fluoro- -2-Methoxy-N-methylpyridin-4-amine (204 mg, yield: 57%). LCMS (ESI): m/z 157 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether:ethyl acetate=8:1).

Step 1s: Preparation of (S)-N-(5-fluoro-2-methoxypyridin-4-yl)-N,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxamide (Compound 1): To a mixture of 5-fluoro-2-methoxy-N-methylpyridin-4-amine (0204-1) (20 mg, 0.13 mmol, 2.0 eq) and triethylamine (53 mg, 0.52 mmol, 8.0 eq) in dichloromethane (2.5 ml) was added triphosgene (19 mg, 0.065 mmol, 1.0 eq) at 0°C. The mixture was warmed to room temperature and stirred for 1.5 hours. The mixture was diluted with water (15 ml) and then extracted with ethyl acetate (10 ml x 2). The combined organic layer was washed with saturated brine (15 ml x 1), dried over anhydrous sodium sulfate and concentrated. The residue was dissolved in dichloromethane (2.5 ml), and (S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (0122-1) (23 mg, 0.065 mmol, 1.0 eq) and N,N-diisopropylethylamine (54 mg, 0.46 mmol, 7.0 eq) were added. The mixture was stirred at room temperature for 1 hour. The solvent was removed under reduced pressure. The residue was purified by preparative thin layer chromatography (dichloromethane:methanol:aqueous ammonia=80:4.5:0.8) to give a white solid (S)-N-(5-fluoro-2-methoxypyridin-4-yl)-N,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxamide (15 mg, yield: 50%). LCMS (ESI): m/z 464 [M+1] ⁺ ; TLC: Rf 0.5 (dichloromethane:methanol=10:1). ^1H NMR (500MHz, MeOD) δ8.81(d,J＝4.9Hz,2H),8.00(d,J＝2.8Hz,1H),7.87(s,1H),7.30(t,J＝4.9Hz,1H),6.64(d,J＝5.5Hz,1H),3.88(s,3H),3.5 5–3.37(m,2H),3.26(d,J＝11.0Hz,2H),3.21(s,3H),2.90–2.65(m,2H) ,2.58(s,3H),2.01(dtd,J＝20.0,13.0,7.3Hz,2H),1.92–1.74(m,2H).

Example 2: Preparation of (S)-N-(5-fluoro-2-methoxypyridin-4-yl)-N,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-thiocarboxamide (Compound 2) (Prepared according to Scheme 3)

To a mixture of 5-fluoro-2-methoxy-N-methylpyridin-4-amine (0204-1) (51.5 mg, 0.33 mmol, 1.0 eq.) in tetrahydrofuran (1 ml) was added lithium bis(trimethylsilyl)amide (1M in tetrahydrofuran, 0.99 ml, 0.99 mmol, 3.0 eq.) at 0°C. The mixture was stirred for 10 minutes. Thiophosgene (114 mg, 0.99 mmol, 3.0 eq.) was added. The mixture was warmed to room temperature and stirred for 1 hour. Water (20 ml) was added to quench the reaction. The aqueous layer was extracted with dichloromethane (10 ml x 3). The combined organic layers were washed with saturated brine (10 ml x 1), dried over anhydrous sodium sulfate and concentrated. The residue was purified by preparative thin layer chromatography (petroleum ether: ethyl acetate = 10: 1) to give a pale yellow oily substance (5-fluoro-2-methoxypyridin-4-yl)(methyl)aminothioyl chloride (33 mg, yield: 43%). LCMS (ESI): m/z 235 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 10: 1). To a mixture of (5-fluoro-2-methoxypyridin-4-yl)(methyl)aminothioyl chloride (33 mg, 0.14 mmol, 1.0 eq) and N,N-diisopropylethylamine (90 mg, 0.70 mmol, 5.0 eq) in dichloromethane (5 ml) was added (S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (0122-1) (50 mg, 0.14 mmol, 1.0 eq). The mixture was stirred at room temperature overnight. The solvent was removed under reduced pressure. The residue was purified by preparative thin layer chromatography (ethyl acetate: dichloromethane: methanol = 20:20:1) to give (S)-N-(5-fluoro-2-methoxypyridin-4-yl)(methyl)aminothioyl chloride (33 mg, 0.14 mmol, 1.0 eq) as a white solid. 4-(2-(4-pyridin-4-yl)-N,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carbothioamide (59 mg, yield: 88%). LCMS (ESI): m/z 480 [M+1] ⁺ ; TLC: Rf 0.5 (dichloromethane:methanol=15:1). ^1H NMR(500MHz,MeOD)δ8.80(d,J＝4.9Hz,2H),7.99(d,J＝3.1Hz,1H),7.85(s,1H),7.30(t,J＝4.9Hz,1H),6.50(d,J＝5.6Hz,1H),3 .88(s,3H),3.80–3.44(m,4H),3.36(d,J＝11.3Hz,3H),2.92–2.69(m,2H),2.57(s,3H),2.19–2.00(m,2H),1.93–1.72(m,2H).

Example 3: Preparation of (S)-N-(3,4-difluorophenyl)-N,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxamide (Compound 3) (Prepared according to Scheme 2)

Step 3a: Preparation of 3,4-difluoro-N-methylaniline (Compound 0204-3):

Under nitrogen protection, sodium methoxide (5.4 mol/L, 7.17 ml, 38.75 mmol, 5.0 eq.) was added to a solution of 3,4-difluoroaniline (1.0 g, 7.75 mmol, 1.0 eq.) and paraformaldehyde (2.1 g, 23.25 mmol, 3.0 eq.) in methanol (10 ml), and the mixture was stirred at room temperature overnight. Sodium borohydride (879 mg, 23.25 mmol, 3.0 eq.) was added to the reaction solution and stirred at 65°C for 2.0 hours. The mixture was concentrated under reduced pressure, and the residue was purified by silica gel column (petroleum ether/ethyl acetate = 10/1 to 6/1) to obtain a yellow oily product 3,4-difluoro-N-methylaniline (600 mg, yield: 54.15%). LCMS (ESI): m/z = 144 [M+1] ⁺ .

Step 3b: Preparation of (S)-N-(3,4-difluorophenyl)-N,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxamide (Compound 3): Under nitrogen protection, triphosgene (37.4 mg, 0.126 mmol, 0.9 equiv) was added to a solution of 3,4-difluoro-N-methylaniline (0204-3) (20 mg, 0.14 mmol, 1.0 equiv) and triethylamine (56 mg, 0.56 mmol, 4.0 equiv) in dichloromethane (5 ml), and the mixture was stirred at room temperature for 1.5 hours. The reaction solution was diluted with water and extracted with dichloromethane (8 ml), the organic phase was dried, 7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (0122-1) (49.4 mg, 0.14 mmol, 1.0 eq.), N,N-diisopropylethylamine (63.21 mg, 0.49 mmol, 3.5 eq.) were added to the above solution, and the mixture was stirred at room temperature for 0.5 hours. The reaction solution was diluted with water and extracted with dichloromethane, the organic phase was dried and concentrated under reduced pressure. The residue was purified by preparative thin layer chromatography (dichloromethane/methanol=15/1, 4% aqueous ammonia) to give a yellow solid product (S)-N-(3,4-difluorophenyl)-N,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxamide (30 mg, yield: 62.94%). LCMS (ESI): m/z=451[M+1] ⁺ . ¹ H NMR(500MHz,MeOD)δ8.80(d,J＝4.9Hz,2H),7.81(s,1H),7.33–7.25(m,2H),7.20(ddd,J＝11.4,7.0,2.5Hz,1H), 7.01(d,J＝8.8Hz,1H),3.41–3.32(m,2H),3.23–3.10(m,5H),2.88–2.63(m,2H),2.56(s,3H),2.00–1.71(m,4H).

Example 4: Preparation of (R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propane-1-thione (Compound 7) (Prepared according to Schemes 4 and 5)

Step 4a: Preparation of dibenzyl 2-(5-fluoro-2-methoxypyridin-4-yl)malonate (compound 0403-7): To a mixture of 5-fluoro-4-iodo-2-methoxypyridine (0202-1) (22.06 g, 87.19 mmol, 1.0 eq), cuprous iodide (1.66 g, 8.72 mmol, 0.1 eq), 2-picolinic acid (2.15 g, 17.44 mmol, 0.2 eq) and cesium carbonate (85.27 g, 261.57 mmol, 3.0 eq) in tetrahydrofuran (130 ml) was added dibenzyl malonate (34.70 g, 12.21 mmol, 1.4 eq). The mixture was heated to 70° C. under nitrogen atmosphere and stirred overnight. The mixture was diluted with water (200 ml) and then extracted with ethyl acetate (100 ml×3). The combined organic layer was washed with saturated brine (100 ml×1), dried over anhydrous sodium sulfate and concentrated to give dibenzyl 2-(5-fluoro-2-methoxypyridin-4-yl)malonate (46.1 g, crude product) as a brown oil. LCMS (ESI): m/z 410 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether:ethyl acetate=10:1).

Step 4b: Preparation of dibenzyl 2-(5-fluoro-2-methoxypyridin-4-yl)-2-methylmalonate (Compound 0404-7): To a mixture of dibenzyl 2-(5-fluoro-2-methoxypyridin-4-yl)malonate (0403-7) (35.70 g, 87.19 mmol, 1.0 eq) and potassium carbonate (36.10 g, 261.57 mmol, 3.0 eq) in acetonitrile (80 ml) was added iodomethane (24.75 g, 174.38 mmol, 2.0 eq). The mixture was stirred at room temperature overnight. The solvent was removed under reduced pressure. The residue was diluted with water (150 ml) and then extracted with ethyl acetate (100 ml x 2). The combined organic layers were washed with saturated brine (50 ml x 1), dried over anhydrous sodium sulfate and concentrated. The residue was diluted with petroleum ether (120 ml) and then stirred at 0°C for 1 hour. The mixture was filtered. The solid was washed with petroleum ether and then dried under vacuum to give a pale yellow solid 2-(5-fluoro-2-methoxypyridin-4-yl)-2-methylmalonic acid dibenzyl ester (24.5 g, yield: 68%). LCMS (ESI): m/z 414 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 10: 1).

Step 4c: Preparation of 2-(5-fluoro-2-methoxypyridin-4-yl)propanoic acid (Compound 0405-7): To a mixture of 2-(5-fluoro-2-methoxypyridin-4-yl)-2-methylmalonic acid dibenzyl ester (0404-7) (24.5 g, 59.32 mmol, 1.0 eq.) in ethyl acetate (100 mL) was added palladium/carbon (10%, 4.0 g). The mixture was stirred at 55° C. under hydrogen balloon pressure for two days. The mixture was filtered. The filtrate was concentrated under reduced pressure. The residue was subjected to column chromatography on silica gel (petroleum ether: ethyl acetate = 6: 1 to 3: 1) to give 2-(5-fluoro-2-methoxypyridin-4-yl)propanoic acid (8.86 g, yield: 75%) as a white solid. LCMS (ESI): m/z 200 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 2: 1).

Step 4d: Preparation of (R)-2-(5-fluoro-2-methoxypyridin-4-yl)propanoic acid (compound 0406-7) and (S)-2-(-5-fluoro-2-methylpyridin-4-yl)propanoic acid (0407-7): Separation of the enantiomers of 2-(5-fluoro-2-methoxypyridin-4-yl)propanoic acid (0405-7) (8.86 g, 44.52 mmol) was carried out by supercritical fluid chromatography (column: ChiralPak IG, 250×30 mm I.D., 10 μm; mobile phase: A is carbon dioxide, B is methanol; eluent: 10% B; flow rate: 60 ml/min; back pressure: 100 bar; column Temperature: 38°C). The first eluting enantiomer was (R)-2-(5-fluoro-2-methoxypyridin-4-yl)propanoic acid (0406-7) (3.75 g, yield: 42%), and the second eluting enantiomer was (S)-2-(-5-fluoro-2-methylpyridin-4-yl)propanoic acid (0407-7) (3.86 g, yield: 44%). Analysis conditions (chromatographic column: ChiralPak IG, 100×4.6 mm I.D., 5 μm; mobile phase: A is carbon dioxide, B is methanol (0.05% diethylamine); eluent: 5% B; flow rate: 2.5 ml/min; back pressure: 100 bar; column temperature: 35°C)

Step 4e: (R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro Preparation of [pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (compound 0413-7): To a mixture of (R)-2-(5-fluoro-2-methoxypyridin-4-yl)propanoic acid (compound 0406-7) (66 mg, 0.33 mmol, 1.0 eq) in acetonitrile (3 ml) were added imidazole trifluoromethanesulfonate (108 mg, 0.50 mmol, 1.5 eq) and carbonyldiimidazole (64 mg, 0.40 mmol, 1.2 eq). The mixture was stirred at room temperature for 2 hours. (S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (Compound 0122-1) (117 mg, 0.33 mmol, 1.0 eq) and N,N-diisopropylethylamine (213 mg, 1.65 mmol, 5.0 eq) were added. The mixture was stirred at room temperature for 3 hours. The mixture was diluted with water (20 ml) and then extracted with ethyl acetate (15 ml x 3). The combined organic layer was washed with saturated brine (15 ml x 1), dried over anhydrous sodium sulfate and concentrated. The residue was purified by preparative thin layer chromatography (dichloromethane:methanol:aqueous ammonia=80:4:0.8) to give a white solid (R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (80 mg, yield: 52%). LCMS (ESI): m/z 463 [M+1] ⁺ ; TLC: Rf 0.5 (dichloromethane:methanol=10:1).

Step 4f: Preparation of (R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propane-1-thione (Compound 7): To a mixture of (S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (compound 0413-7) (80 mg, 0.18 mmol, 1.0 eq.) in toluene (5 ml) was added Lawesson's reagent (85 mg, 0.21 mmol, 1.2 eq.). The mixture was heated at 125°C in a microwave reactor for 40 minutes. The mixture was diluted with water (20 ml) and then extracted with ethyl acetate (15 ml x 3). The combined organic layers were washed with saturated brine (15 ml x 1), dried over anhydrous sodium sulfate and concentrated. The residue was purified by preparative thin layer chromatography (dichloromethane:methanol:aqueous ammonia=80:3.5:0.8) to give (R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propane-1-thione (30 mg, yield: 36%) as a white solid. LCMS (ESI): m/z 479 [M+1] ⁺ ; TLC: Rf 0.6 (dichloromethane:methanol=10:1). ¹ HNMR(500MHz,MeOD)δ8.81(t,J＝4.4Hz,2H),7.88(dt,J＝41.5,18.1Hz,2H),7.30(t,J＝4.1Hz,1H),6.95–6.81(m,1H),4.54(dt,J＝14.2, 6.8Hz,1H),4.18–3.66(m,7H),2.97–2.76(m,2H),2.58(dd,J＝9.6,4.7Hz,3H),2.32–2.06(m,2H),2.05–1.78(m,2H),1.63–1.51(m,3H).

Example 5: Preparation of 2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one-3,3,3-d3 (Compound 57) (Prepared according to Schemes 1 and 4)

Step 5a: Preparation of dibenzyl 2-(5-fluoro-2-methoxypyridin-4-yl)-2-(methyl-d3)malonate (Compound 0404-57): Under nitrogen protection, to a mixed solution of dibenzyl 2-(5-fluoro-2-methoxypyridin-4-yl)malonate (0403-7) (500 mg, 1.22 mmol, 1.0 eq.), potassium carbonate (507 mg, 3.67 mmol, 3.0 eq.) in N,N-dimethylformamide (5 ml) was added deuterated iodomethane (355 mg, 2.44 mmol, 2.0 eq.), and the mixture was stirred at room temperature for three hours. The reaction solution was diluted with water and extracted with ethyl acetate. The organic phase was dried and concentrated under reduced pressure. The residue was purified by silica gel column (petroleum ether/ethyl acetate) Ester = 3/1) to obtain a white oily product, 2-(5-fluoro-2-methoxypyridin-4-yl)-2-(methyl-d3)malonic acid dibenzyl ester (510 mg, yield: 98.07%). LCMS (ESI): m/z = 427 [M+1] ⁺ .

Step 5b: Preparation of 2-(5-fluoro-2-methoxypyridin-4-yl)propionic acid-3,3,3-d3 acid (Compound 0405-57): Under hydrogen protection, palladium carbon (102 mg, 20% mass fraction) was added to a mixture of 2-(5-fluoro-2-methoxypyridin-4-yl)-2-(methyl-d3)malonate (Compound 0404-57) (510 mg, 1.19 mmol, 1.0 equivalent) in ethyl acetate (5 ml). The mixture was stirred at 55°C overnight. The mixture was filtered and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column (petroleum ether/ethyl acetate = 2/1) to obtain a white oily product 2-(5-fluoro-2-methoxypyridin-4-yl)propionic acid-3,3,3-d3 acid (120 mg, yield: 49.38%). LCMS (ESI): m/z=203[M+1] ⁺ .

Step 5c: Preparation of 2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7′-methyl-6′-(pyrimidin-2-yl)-3′,4′-dihydro-1′H-spiro[pyrrolidine-3,2′-[1,8]naphthyridine]-1-yl)propan-1-one-3,3,3-d3 (Compound 57 (0412-57)): 2-(5-fluoro-2-methoxypyridin-4-yl)propanoic acid-3,3,3-d3. A solution of 7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (0122-1) (50 mg, 0.143 mmol, 1.0 eq.) and N,N-diisopropylethylamine (74 mg, 0.571 mmol, 4.0 eq.) in dichloromethane (3 ml) was stirred at room temperature for 10 minutes. Then, 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (66 mg, 0.171 mmol, 1.2 eq.) was added to the mixture and stirred at room temperature for one hour. The reaction solution was diluted with water and extracted with dichloromethane, and the organic phase was dried and concentrated under reduced pressure. The residue was purified by preparative thin layer chromatography (dichloromethane/methanol/aqueous ammonia = 80/4.5/0.8) to give a yellow solid product 2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one-3,3,3-d3 (40 mg, yield: 60.61%). LCMS (ESI): m/z=466[M+1] ⁺ . ¹ HNMR(500MHz,MeOD)δ8.87–8.74(m,2H),8.02–7.80(m,2H),7.31(s,1H),6.82–6.67(m,1H),4.21(dd,J＝42.9,6.0 Hz,1H),3.93–3.82(m,3H),3.76–3.33(m,4H),2.98–2.75(m,2H),2.59(dd,J=12.9,4.1Hz,3H),2.21–1.76(m,4H).

Example 6: Preparation of 2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propane-1-thione-3,3,3-d3 (Compound 58) (Prepared according to Scheme 5)

A mixed solution of 2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one-3,3,3-d3(0412-57) (50 mg, 0.107 mmol, 1.0 eq.), Lawesson's reagent (53 mg, 0.129 mmol, 1.2 eq.) in toluene (2.5 ml) was stirred at 125°C in a microwave reactor for one hour. The reaction solution was diluted with water and extracted with dichloromethane. The organic phase was dried and concentrated under reduced pressure. The residue was purified by preparative thin layer chromatography (dichloromethane/methanol/aqueous ammonia = 80/4.5/0.8) to give a yellow solid product 2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propane-1-thione-3,3,3-d3 (33 mg, yield: 63.46%). LCMS (ESI): m/z＝484[M+1] ⁺ . ¹ HNMR (500MHz, MeOD) δ8.82(t,J＝4.2Hz,2H),7.99–7.76(m,2H),7.31(t,J＝4.8Hz,1H),6.96–6.83(m,1H),4.52 (dd,J＝48.3,6.5Hz,1H),4.22–3.90(m,3H),3.86(dd,J＝15.1,5.9Hz,3H),3.82–3.62(m,1 H),2.97–2.77(m,2H),2.59(dd,J＝9.7,7.2Hz,3H),2.34–2.09(m,2H),2.07–1.77(m,2H).

Example 7: Preparation of (2R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-(6'-(pyrimidin-2-yl)-7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 34) (Prepared according to Schemes 1 and 4)

Step 7a: Preparation of tert-butyl 3-hydroxy-3-((trimethylsilyl)ethynyl)pyrrolidine-1-carboxylate (Compound 0102-34): Under nitrogen protection, n-butyl lithium (9.5 ml, 23.8 mmol, 1.1 eq) was added dropwise to a solution of ethynyltrimethylsilane (2.55 g, 25.9 mmol, 1.2 eq) in tetrahydrofuran (40 ml) at -70°C, and the mixture was stirred at -70°C for 1.0 hour. Then, a solution of 1-tert-butyloxycarbonyl-3-pyrrolidone (0101-34) (4.0 g, 21.6 mmol, 1.0 eq) in tetrahydrofuran (10 ml) was added dropwise to the reaction solution at -60°C, the cryogenic device was removed, and the mixture was stirred at room temperature overnight. The reaction solution was quenched with ammonium chloride solution and extracted with ethyl acetate. The organic phase was dried and concentrated under reduced pressure to give a yellow oily crude product of tert-butyl 3-hydroxy-3-((trimethylsilyl)ethynyl)pyrrolidine-1-carboxylate (6.04 g). The crude product was used directly in the next step without further purification.

Step 7b: Preparation of tert-butyl 3-ethynyl-3-hydroxypyrrolidine-1-carboxylate (Compound 0103-34): Under nitrogen protection, potassium carbonate (5.80 g, 42.3 mmol, 2.0 eq.) was added to a solution of tert-butyl 3-hydroxy-3-((trimethylsilyl)ethynyl)pyrrolidine-1-carboxylate (0102-34) (6.00 g, 21.2 mmol, 1.0 eq.) in methanol (100 ml), and the mixture was stirred at room temperature for 1.5 hours. The solvent was removed under reduced pressure, the residue was diluted with water and extracted with ethyl acetate, and the organic phase was dried and concentrated under reduced pressure. The residue was purified by silica gel column (petroleum ether/ethyl acetate=10/1) to obtain a yellow oily product, tert-butyl 3-ethynyl-3-hydroxypyrrolidine-1-carboxylate (4.43 g, two-step yield: 97.1%).

Step 7c: Preparation of tert-butyl 3-acetoxy-3-ethynyl-pyrrolidine-1-carboxylate (Compound 0104-34): Under nitrogen protection, acetyl chloride (1.98 g, 25.2 mmol, 1.2 eq) was added to a solution of tert-butyl 3-ethynyl-3-hydroxypyrrolidine-1-carboxylate (0103-34) (4.43 g, 21.0 mmol, 1.0 eq) and N,N-diisopropylethylamine (4.06 g, 31.5 mmol, 1.5 eq) in dichloromethane (100 ml) at 0°C, and the mixture was stirred at 0°C for 1 hour. The reaction solution was quenched with water and extracted with dichloromethane. The organic phase was dried and concentrated under reduced pressure. The residue was purified by silica gel column (petroleum ether/ethyl acetate=20/1 to 5/1) to give yellow oily product 3-acetoxy-3-ethynyl-pyrrolidine-1-carboxylic acid tert-butyl ester (3.07 g, yield: 57.8%).

Step 7d: Preparation of tert-butyl 3-ethynyl-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (Compound 0105-34): Under nitrogen protection, to a solution of 4-methoxybenzylamine (3.07 g, 22.3 mmol, 2.0 equiv.) and cuprous chloride (111 mg, 1.1 mmol, 0.1 equiv.) in tetrahydrofuran (30 ml) at 70°C, a solution of tert-butyl 3-acetoxy-3-ethynyl-pyrrolidine-1-carboxylate (0104-34) (2.83 g, 11.2 mmol, 1.0 equiv.) in tetrahydrofuran (10 ml) was added, and the mixture was stirred at 70°C for 1 hour. The reaction solution was diluted with water and extracted with ethyl acetate, and the organic phase was dried and concentrated under reduced pressure. The residue was purified by silica gel column (petroleum ether/ethyl acetate = 10/1 to 4/1) to obtain a yellow oily product 3-ethynyl -tert-Butyl 3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (2.56 g, yield: 69.4%).

Step 7e: Preparation of 2-chloro-3-iodo-6-(trifluoromethyl)pyridine (Compound 0107-34): To a mixture of 2-chloro-6-(trifluoromethyl)pyridin-3-amine (0106-34) (1.5 g, 7.63 mmol, 1.0 eq) and 6M dilute hydrochloric acid (7.6 mL, 45.78 mmol, 6.0 eq) in acetonitrile (5 mL) was added dropwise a solution of sodium nitrite (0.63 g, 9.16 mmol, 1.2 eq) in water (503 mL) at 0°C. The mixture was stirred at 0°C for 35 minutes. A solution of potassium iodide (2.53 g, 15.26 mmol, 2.0 eq) in water (5 mL) was added. The mixture was warmed to room temperature and then stirred overnight. 2M sodium hydroxide solution was slowly added to adjust pH=8, and the aqueous layer was extracted with ethyl acetate (15 mL×3). The combined organic layer was washed with saturated brine (15 ml x 1), dried over anhydrous sodium sulfate and concentrated. The residue was subjected to column chromatography on silica gel (petroleum ether: ethyl acetate = 100: 1) to give a white solid 2-chloro-3-iodo-6-(trifluoromethyl)pyridine (1.77 g, yield: 76%). LCMS (ESI): m/z 308 [M+1] ⁺ ; TLC: Rf 0.8 (petroleum ether).

Step 7f: Preparation of tert-butyl 3-((2-chloro-6-(trifluoromethyl)pyridin-3-yl)ethynyl)-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (Compound 0108-34): To a mixture of 2-chloro-3-iodo-6-(trifluoromethyl)pyridine (0107-34) (1.0 g, 3.26 mmol, 1.08 equiv), bistriphenylphosphine palladium dichloride (106 mg, 0.15 mmol, 0.05 equiv) and cuprous iodide (29 mg, 0.15 mmol, 0.05 equiv) in triethylamine (10 ml) was added tert-butyl 3-ethynyl-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (0105-34) (1.0 g, 3.03 mmol, 1.0 equiv). The mixture was heated to 80°C under nitrogen atmosphere and reacted overnight. The solvent was removed under reduced pressure. The residue was diluted with water (30 ml) and then extracted with ethyl acetate (15 ml x 3). The combined organic layer was washed with saturated brine (20 ml x 1), dried over anhydrous sodium sulfate and concentrated. The residue was subjected to column chromatography on silica gel (petroleum ether: ethyl acetate = 5: 1 to 2: 1) to obtain a light yellow oily substance tert-butyl 3-((2-chloro-6-(trifluoromethyl)pyridin-3-yl)ethynyl)-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (1.36 g, yield: 88%). LCMS (ESI): m/z 511 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 3: 1).

Step 7g: Preparation of tert-butyl 3-(2-(2-chloro-6-(trifluoromethyl)pyridin-3-yl)ethyl)-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (Compound 0109-34): To a mixture of tert-butyl 3-((2-chloro-6-(trifluoromethyl)pyridin-3-yl)ethynyl)-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (0108-34) (1.33 g, 2.61 mmol, 1.0 eq) in methanol (10 mL) was added platinum dioxide (118 mg, 0.52 mmol, 0.2 eq). The mixture was stirred at room temperature under hydrogen balloon pressure for 2 hours. The mixture was filtered. The filtrate was concentrated under reduced pressure to give a light yellow oily substance, tert-butyl 3-(2-(2-chloro-6-(trifluoromethyl)pyridin-3-yl)ethyl)-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (1.29 g, yield: 96%). LCMS (ESI): m/z 515 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether:ethyl acetate=3:1).

Step 7h: Preparation of tert-butyl 1'-(4-methoxybenzyl)-7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (Compound 0110-34): To a mixture of tert-butyl 3-(2-(2-chloro-6-(trifluoromethyl)pyridin-3-yl)ethyl)-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (0109-34) (1.29 g, 2.51 mmol, 1.0 equiv), palladium acetate (28 mg, 0.13 mmol, 0.05 equiv) and RuPhos (117 mg, 0.25 mmol, 0.1 equiv) in dioxane (12 ml) was added. Sodium tert-butoxide (0.48 g, 5.02 mmol, 2.0 eq) was added to the mixture. The mixture was heated to 115°C in a microwave reactor for 1 hour. The solvent was removed under reduced pressure. The residue was subjected to column chromatography on silica gel (petroleum ether: ethyl acetate = 8:1 to 3:1) to give a pale yellow oily substance 1'-(4-methoxybenzyl)-7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (724 mg, yield: 60%). LCMS (ESI): m/z 478 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 5:1).

Step 7i: Preparation of tert-butyl 7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (Compound 0112-34): A mixture of tert-butyl 1'-(4-methoxybenzyl)-7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (0110-34) (724 mg, 1.52 mmol, 1.0 eq) in methanolic hydrogen chloride solution (4M solution, 7.5 mL) was heated to 70°C for 2 hours. The solvent was removed under reduced pressure. The residue was dissolved in tetrahydrofuran (10 mL) and water (10 mL). Solid sodium carbonate was added to adjust the pH to 9. Di-tert-butyl dicarbonate (332 mg, 1.52 mmol, 1.0 eq) was added, and the mixture was stirred at room temperature for 1 hour. The mixture was diluted with water (20 ml), and then extracted with ethyl acetate (10 ml×3). The combined organic layer was washed with saturated brine (10 ml×1), dried over anhydrous sodium sulfate and concentrated to give a pale yellow oily substance, tert-butyl 7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (610 mg, crude product). LCMS (ESI): m/z 358[M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether:ethyl acetate=4:1).

Step 7j: Preparation of tert-butyl 6'-bromo-7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (Compound 0115-34): To a mixture of tert-butyl 7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (0112-34) (543 mg, 1.52 mmol, 1.0 eq) in dichloromethane (10 mL) was added dibromohydantoin (261 mg, 0.91 mmol, 0.6 eq) at 0°C. The mixture was stirred at 0°C for 1 hour. Saturated aqueous sodium sulfite solution (20 mL) was added to quench the reaction. The aqueous layer was extracted with dichloromethane (10 mL x 3). The combined organic layer was washed with saturated brine (10 ml x 1), dried over anhydrous sodium sulfate and concentrated. The residue was separated by column chromatography on silica gel (petroleum ether: ethyl acetate = 6: 1) to give a pale yellow oily substance 6'-bromo-7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (659 mg, yield: 99%). LCMS (ESI): m/z 436 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 4: 1).

Step 7k: Preparation of (1-(tert-butyloxycarbonyl)-7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-6'-yl)boronic acid (Compound 0117-34): To tert-butyl 6'-bromo-7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (0115-34) (250 mg, 0.57 mmol, 1.0 equiv. ), Xphos-Pd-G2 (9 mg, 0.011 mmol, 0.02 eq), Xphos (8 mg, 0.017 mmol, 0.03 eq), potassium acetate (140 mg, 1.43 mmol, 2.5 eq) and sodium tert-butoxide (1.4 mg, 0.014 mmol, 0.025 eq) were added to a mixture of methanol (6 ml) and ethylene glycol (0.6 ml). Tetrahydroxydiboron (129 mg, 1.43 mmol, 2.5 eq) was added. The mixture was heated to 53°C under a nitrogen atmosphere for 10 hours. The solvent was removed under reduced pressure. The residue was diluted with water (20 ml). 2M sodium hydroxide solution was added to adjust the pH to 12, and then the mixture was washed with methyl tert-butyl ether (8 ml×3). 2M dilute hydrochloric acid solution was added to the aqueous layer to adjust pH = 7, then extracted with ethyl acetate (10 ml x 3). The combined organic layer was washed with saturated brine (10 ml x 1), dried over anhydrous sodium sulfate and concentrated to give a white solid (1-(tert-butyloxycarbonyl)-7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-6'-yl)boronic acid (151 mg, yield: 66%). LCMS (ESI): m/z 402 [M+1] ⁺ ; TLC: Rf 0.5 (dichloromethane: methanol = 10: 1).

Step 71: Preparation of tert-butyl 6'-(pyrimidin-2-yl)-7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (Compound 0119-34): To (1-(tert-butyloxycarbonyl)-7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-6'-yl)boronic acid (0117-34) (151 mg, 0.38 mmol, 1.0 eq.), Xphos-Pd-G2 (9 mg, 0.011 mmol, 0.03 eq.), Xphos (5.2 mg, 0.011 mmol, 0.03 eq.) and sodium carbonate (120 mg, 1.13 mmol, 3.0 eq.) were added to a mixture of toluene (2.5 ml), ethanol (2.5 ml) and water (1 ml). The mixture was heated to 55° C. under a nitrogen atmosphere for 6 hours. The solvent was removed under reduced pressure. The residue was subjected to column chromatography on silica gel (dichloromethane: methanol = 100: 1 to 50: 1) to give pale yellow oily tert-butyl 6'-(pyrimidin-2-yl)-7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (115 mg, yield: 70%). LCMS (ESI): m/z 436 [M+1] ⁺ ; TLC: Rf 0.5 (dichloromethane: methanol = 20: 1).

Step 7m: Preparation of 6'-(pyrimidin-2-yl)-7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (Compound 0121-34): A mixture of tert-butyl 6'-(pyrimidin-2-yl)-7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (0119-34) (49 mg, 0.113 mmol, 1.0 eq) in methanolic hydrogen chloride solution (4M solution, 1.5 mL) was stirred at room temperature for 3.5 hours. The solvent was removed under reduced pressure. The residue was dried under vacuum to give 6'-(pyrimidin-2-yl)-7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (46 mg, crude) as a pale yellow oil. LCMS (ESI): m/z 336 [M+1] ⁺ ; TLC: Rf 0.5 (dichloromethane:methanol=10:1).

Step 7n: Preparation of (2R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-(6'-(pyrimidin-2-yl)-7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidin-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 34): To a mixture of (R)-2-(5-fluoro-2-methoxypyridin-4-yl)propanoic acid (Compound 0406-7) (22.5 mg, 0.113 mmol, 1.0 eq) in acetonitrile (3 mL) were added imidazole triflate (37 mg, 0.17 mmol, 1.5 eq) and carbonyldiimidazole (22 mg, 0.14 mmol, 1.2 eq). The mixture was stirred at room temperature for 1.5 hours. 6'-(pyrimidin-2-yl)-7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (Compound 0121-34) (46 mg, 0.113 mmol, 1.0 eq) and N,N-diisopropylethylamine (73 mg, 0.57 mmol, 5.0 eq) were added. The mixture was stirred at room temperature overnight. The mixture was diluted with water (30 mL) and then extracted with ethyl acetate (15 mL×3). The combined organic layer was washed with saturated brine (20 mL×1), dried over anhydrous sodium sulfate and concentrated. The residue was purified by preparative thin layer chromatography (petroleum ether:ethyl acetate=1:3) to give a white solid (2R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-(6'-(pyrimidin-2-yl)-7'-(trifluoromethyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (16 mg, yield: 28%). LCMS (ESI): m/z 517 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether:ethyl acetate=1:3). ¹ HNMR (500 MHz, MeOD) δ8.83 (s, 2H), 7.95 (t, J=22.6 Hz, 1H),7.62(d,J＝10.2Hz,1H),7.43(d,J＝2.1Hz,1H),6.81–6.70(m,1H),4.34–4.14(m,1H),3.86(d,J＝10.8Hz,3H), 3.78–3.38(m,4H),3.00–2.62(m,2H),2.00(dddd,J＝47.1,41.6,24.0,15.9Hz,4H),1.46(dd,J＝11.5,5.9Hz,3H).

Example 8: Preparation of (2R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-(7'-fluoro-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 37) (Prepared according to Schemes 1 and 4)

Step 8a: Preparation of tert-butyl 3-((2,6-difluoropyridin-3-yl)ethynyl)-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (Compound 0108-37): To a mixture of 2,6-difluoro-3-iodopyridine (422 mg, 1.75 mmol, 1.05 eq), bistriphenylphosphine palladium dichloride (59 mg, 0.084 mmol, 0.05 eq) and cuprous iodide (16 mg, 0.084 mmol, 0.05 eq) in triethylamine (8 ml) was added tert-butyl 3-ethynyl-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (Compound 0105-34) (550 mg, 1.67 mmol, 1.0 eq). The mixture was heated to 80° C. under nitrogen atmosphere for 3 hours. The solvent was removed under reduced pressure. The residue was diluted with water (30 ml) and then extracted with ethyl acetate (20 ml x 3). The combined organic layer was washed with saturated brine (20 ml x 1), dried over anhydrous sodium sulfate and concentrated. The residue was subjected to column chromatography on silica gel (petroleum ether: ethyl acetate = 5: 1 to 1: 1) to obtain a light yellow oily substance tert-butyl 3-((2,6-difluoropyridin-3-yl)ethynyl)-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (600 mg, yield: 81%). LCMS (ESI): m/z 444 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 3: 1).

Step 8b: Preparation of tert-butyl 7'-fluoro-1'-(4-methoxybenzyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (Compound 0110-37): To a mixture of tert-butyl 3-((2,6-difluoropyridin-3-yl)ethynyl)-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (0108-37) (600 mg, 1.35 mmol, 1.0 eq) in methanol (10 mL) was added platinum dioxide (62 mg, 0.27 mmol, 0.2 eq). The mixture was stirred at room temperature under hydrogen balloon pressure for 2.5 hours. The mixture was filtered. The filtrate was concentrated under reduced pressure. The residue was separated by column chromatography on silica gel (petroleum ether:ethyl acetate=5:1 to 3:1) to give a pale yellow oily substance, tert-butyl 7'-fluoro-1'-(4-methoxybenzyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (315 mg, yield: 55%). LCMS (ESI): m/z 428 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether:ethyl acetate=3:1).

Step 8c: Preparation of tert-butyl 7'-fluoro-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (Compound 0112-37): To a mixture of tert-butyl 7'-fluoro-1'-(4-methoxybenzyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (0110-37) (315 mg, 0.74 mmol, 1.0 eq) in dichloromethane (6 mL) was added trifluoroacetic acid (1.5 mL). The mixture was stirred at room temperature for 4.5 hours. The solvent was removed under reduced pressure. The residue was dissolved in water (10 mL) and tetrahydrofuran (10 mL). Solid sodium carbonate was added to adjust the pH to 9. Di-tert-butyl dicarbonate (403 mg, 1.84 mmol, 2.5 eq) was added, and the mixture was stirred at room temperature for 1 hour. The mixture was diluted with water (30 mL), and then extracted with ethyl acetate (20 mL×3). The combined organic layer was washed with saturated brine (20 mL×1), dried over anhydrous sodium sulfate and concentrated. The residue was subjected to column chromatography on silica gel (petroleum ether: ethyl acetate = 5:1) to give a light yellow oily substance, tert-butyl 7'-fluoro-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (227 mg, yield: 100%). LCMS (ESI): m/z 308[M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether:ethyl acetate=3:1).

Step 8d: Preparation of tert-butyl 7'-fluoro-6'-iodo-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (Compound 0115-37): To a mixture of tert-butyl 7'-fluoro-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (0112-37) (227 mg, 0.74 mmol, 1.0 equiv) in acetonitrile (3.5 mL) at 0°C was added N-iodosuccinimide (166 mg, 0.74 mmol, 1.0 equiv). The mixture was stirred at 0°C for 1 hour. Saturated aqueous sodium sulfite solution (20 mL) was added to quench the reaction. The aqueous layer was extracted with ethyl acetate (15 mL x 3). The combined organic layer was washed with saturated brine (20 mL x 1), dried over anhydrous sodium sulfate and concentrated to give a pale yellow oily substance, tert-butyl 7'-fluoro-6'-iodo-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (277 mg, yield: 87%). LCMS (ESI): m/z 434 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether:ethyl acetate=3:1).

Step 8e: Preparation of tert-butyl 7'-fluoro-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (Compound 0119-37): To tert-butyl 7'-fluoro-6'-iodo-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (0115-37) (240 mg, 0.55 mmol, 1.0 equiv), Xphos- Pd-G3 (23 mg, 0.028 mmol, 0.05 eq), Xphos (13.3 mg, 0.028 mmol, 0.05 eq), cuprous iodide (10.5 mg, 0.055 mmol, 0.1 eq) and cesium fluoride (167 mg, 1.10 mmol, 2.0 eq) were added to a mixture of N,N-dimethylformamide (6 ml) and 2-(tributyltinyl)pyrimidine (406 mg, 1.10 mmol, 2.0 eq). The mixture was heated to 100°C in a microwave reactor for 50 minutes. The mixture was diluted with water (30 ml) and then extracted with ethyl acetate (10 ml x 3). The combined organic layer was washed with saturated brine (20 ml x 1), dried over anhydrous sodium sulfate and concentrated. The residue was purified by preparative thin layer chromatography (ethyl acetate:petroleum ether=3:2) to give a pale yellow oily substance, tert-butyl 7'-fluoro-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (43 mg, yield: 20%). LCMS (ESI): m/z 386 [M+1] ⁺ ; TLC: Rf 0.5 (ethyl acetate:petroleum ether=3:2).

Step 8f: Preparation of 7'-fluoro-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (Compound 0121-37): A mixture of tert-butyl 7'-fluoro-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (0119-37) (42 mg, 0.11 mmol, 1.0 eq) in ethyl acetate solution of hydrogen chloride (4M solution, 2.5 mL) was stirred at room temperature for 2.5 hours. The solvent was removed under reduced pressure. The residue was dried under vacuum to give pale yellow solid 7'-fluoro-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (39 mg, crude product). LCMS (ESI): m/z 286 [M+1] ⁺ ; TLC: Rf 0.3 (dichloromethane:methanol=10:1).

Step 8g: Preparation of (2R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-(7'-fluoro-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidin-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 37): To (R)-2-(5-fluoro-2-methoxypyridin-4-yl)propanoic acid (Compound 0406-7) (22 mg, 0. 11 mmol, 1.0 equiv), 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (50 mg, 0.13 mmol, 1.2 equiv) and N,N-diisopropylethylamine (71 mg, 0.55 mmol, 5.0 equiv) were added to a mixture of dichloromethane (3 ml) with 7'-fluoro-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine -3,2'-[1,8]naphthyridine] dihydrochloride (Compound 0121-37) (39 mg, 0.11 mmol, 1.0 eq). The mixture was stirred at room temperature for 1 hour. The mixture was diluted with water (30 ml) and then extracted with ethyl acetate (15 ml × 3). The combined organic layer was washed with saturated brine (20 ml × 1), dried over anhydrous sodium sulfate and concentrated. The residue was purified by preparative thin layer chromatography (dichloromethane: ethyl acetate: methanol = 10: 10: 1) to give a white solid (2R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-(7'-fluoro-6'-(pyrimidine-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propane-1-one (25 mg, yield: 48%). LCMS (ESI): m/z 476 [M+1] ⁺ ; TLC: Rf 0.5 (dichloromethane: methanol = 15: 1). ¹ H NMR (500 MHz, MeOD) δ 8.77 (s, 2H), 8.13 (d, J = 9.2 Hz, 1H), 7.91 (d, J = 64.6 Hz, 1H), 7.28 (s, 1H), 6.75 (d, J = 22.1 Hz, 1H), 4.22 (d, J = 36.4 Hz, 1H), 3.87 (d, J = 12.1 Hz, 3H), 3.77-3.36 (m, 4H), 2.72 (d, J = 114.3 Hz, 2H), 2.16-1.71 (m, 4H), 1.43 (dd, J = 13.0, 6.6 Hz, 3H).

Example 9: Preparation of 2-(5-fluoro-2-methoxypyridin-4-yl)-3-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)-3-oxopropionitrile (Compound 41)

Under nitrogen protection, a solution of 5-fluoro-4-iodo-2-methoxypyridine (0202-1) (500 mg, 1.98 mmol, 1.0 eq) in tetrahydrofuran (5 ml) was added dropwise to a solution of ethyl 2-cyanoacetate (335 mg, 2.96 mmol, 1.5 eq), picolinic acid (50 mg, 0.40 mmol, 0.2 eq), cuprous iodide (37.5 mg, 0.20 mmol, 0.1 eq) and cesium carbonate (730 mg, 2.24 mmol, 1.1 eq) in tetrahydrofuran (20 ml), and the reaction was stirred at 70° C. overnight. After the reaction was completed, the mixture was filtered, the filter cake was washed with ethyl acetate (20 ml×3), and the combined filtrate was washed with saturated aqueous ammonium chloride (100 ml) and saturated brine in sequence, dried over sodium sulfate, filtered, and concentrated under reduced pressure. The residue was purified by silica gel column (eluent: 10% to 20% ethyl acetate in petroleum ether) to give ethyl 2-cyano-2-(5-fluoro-2-methoxypyridin-4-yl)acetate (355 mg, yield: 75.2%) as a white solid product. LCMS (ESI): m/z=239[M+1] ⁺ . Under nitrogen protection, N,N-diisopropylethylamine (0.5 ml, 2.87 mmol, 18 eq) was added to a toluene (10 ml) solution of ethyl 2-cyano-2-(5-fluoro-2-methoxypyridin-4-yl)acetate (43 mg, 0.16 mmol, 1.0 eq) and 7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (Compound 0122-1) (50 mg, 0.18 mmol, 1.0 eq), and the reaction was stirred at 120° C. overnight. After the reaction was completed, the reaction mixture was diluted with water and extracted with ethyl acetate (10 ml×3), and the combined organic phase was washed with saturated brine, dried over sodium sulfate, filtered, and concentrated under reduced pressure at 45° C. The residue was purified by preparative thin layer chromatography (eluent: dichloromethane/methanol=10/1) to give a white solid product 2-(5-fluoro-2-methoxypyridin-4-yl)-3-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)-3-oxopropanenitrile (15 mg, yield: 17.6%). LCMS (ESI): m/z=474.30 [M+1] ⁺ . ¹ HNMR (500 MHz, DMSO) δ8.88 (d, J=4.6 Hz, 2H), 8.38– 8.25(m,1H),7.97(d,J＝6.3Hz,1H),7.48–7.31(m,2H),6.99–6.88(m,1H),5.92–5.80(m,1H),4.08–3.90(m,4H),3.83–3.69(m,2H), 3.58(d,J＝9.9Hz,2H),2.83(dd,J＝16.2,6.3Hz,2H),2.65(d,J＝8.4Hz,3H),2.15–2.04(m,2H),1.85(tdd,J＝21.6,15.6,8.4Hz,2H).

Example 10: Preparation of 2-(2-methoxy-5-(methylsulfonyl)pyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 31) (Prepared according to Scheme 4)

Step 10a: Preparation of dimethyl 2-(2-methoxy-5-(methylthio)pyridin-4-yl)malonate (Compound 0403-31): To a mixture of 6-methoxy-4-methylpyridin-3-amine (1 g, 7.2 mmol, 1.0 eq) in dimethyl disulfide (10 ml) was added tert-butyl nitrite (5.96 g, 57.9 mmol, 8.0 eq) and the mixture was stirred at 50°C for half an hour. The reaction solution was diluted with water, extracted with ethyl acetate, and the organic phase was dried and concentrated under reduced pressure to give a crude oil. The residue was purified by silica gel column chromatography (eluent: petroleum ether) to give 2-methoxy-4-methyl-5-(methylthio)pyridine (710 mg, yield 59%) as a yellow oil. MS (ES ⁺ ): m/z=170 (M+H) ⁺ . Under nitrogen protection, a tetrahydrofuran solution of lithium diisopropylamide (1.6M, 6.7 ml, 10.8 mmol, 3.0 eq) was added dropwise to a tetrahydrofuran (5 ml) solution of 2-methoxy-4-methyl-5-(methylthio)pyridine (610 mg, 3.6 mmol, 1.0 eq) at -30°C. After the reaction mixture was stirred at -30°C for 1 hour, dimethyl carbonate (975 mg, 10.8 mmol, 3.0 eq) was added dropwise. After the addition was complete, the reaction mixture was heated to 25°C and stirred for 1 hour. The reaction solution was diluted with water and extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 10/1) to obtain yellow oily 2-(2-methoxy-5-(methylthio)pyridin-4-yl)malonate (290 mg, yield 29%). LCMS (ESI): m/z = 286 [M+1] ⁺ .

Step 10b: Preparation of dimethyl 2-(2-methoxy-5-(methylthio)pyridin-4-yl)-2-methylmalonate (Compound 0404-31): Under nitrogen protection, iodomethane (145 mg, 1.0 mol, 1.0 eq.) was added to a mixture of dimethyl 2-(2-methoxy-5-(methylthio)pyridin-4-yl)malonate (0403-31) (290 mg, 1.0 mmol, 1.0 eq.) and cesium carbonate (501 mg, 1.5 mmol, 1.5 eq.) in N,N-dimethylformamide (5 ml), and the mixture was stirred at 35°C overnight. After cooling to room temperature, the reaction solution was diluted with water and extracted with ethyl acetate. The organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 3/1) to give yellow oily product 2-(2-methoxy-5-(methylthio)pyridin-4-yl)-2-methylmalonic acid dimethyl ester (275 mg, yield 95%). LCMS (ESI): m/z = 300 [M+1] ⁺ .

Step 10c: Preparation of 2-(2-methoxy-5-(methylsulfonyl)pyridin-4-yl)propanoic acid (Compound 0405-31): A mixture of dimethyl 2-(2-methoxy-5-(methylthio)pyridin-4-yl)-2-methylmalonate (0404-31) (275 mg, 0.9 mmol, 1.0 eq) and sodium hydroxide (183.8 mg, 4.6 mmol, 5.0 eq) in ethanol/water = 5/1 (10 ml/2 ml) was stirred at 85°C overnight. The reaction solution was adjusted to pH 2-3 with dilute hydrochloric acid, extracted with ethyl acetate, and the organic phase was dried and concentrated under reduced pressure to give 2-(5-fluoro-2-methylbenzofuran-6-yl)propanoic acid (160 mg, yield 76.9%) as a yellow oil. LCMS (ESI): m/z = 228 [M+1] ⁺ . A mixture of 2-(2-methoxy-5-(methylthio)pyridin-4-yl)propanoic acid (160 mg, 0.7 mmol, 1.0 eq) and potassium peroxymonosulfonate (866.6 mg, 1.4 mmol, 2 eq) in ethanol (5 ml) was stirred at room temperature overnight. The reaction solution was diluted with ammonium chloride. The mixture was diluted with ethyl acetate and extracted with ethyl acetate. The organic phase was dried and concentrated under reduced pressure to obtain a crude oil. The crude product was purified by column chromatography (eluent: dichloromethane/methanol = 10/1) to obtain 2-(2-methoxy-5-(methylsulfonyl)pyridin-4-yl)propanoic acid (160 mg, yield 87.9%). LCMS (ESI): m/z = 260 [M+1] ⁺ .

Step 10d: Preparation of 2-(2-methoxy-5-(methylsulfonyl)pyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 31, 0412-31): To 2-(2-methoxy-5-(methylsulfonyl)pyridin-4-yl)propanoic acid (0405-31) (50 mg, 0.2 mmol, 1.05 equiv), 7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (90.5 mg, 0.24 mmol, 1.3 molar amounts) was added to a mixture of (pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (0122-1) (65 mg, 0.18 mmol, 1.0 molar amounts) and N,N-diisopropylethylamine (94.5 mg, 0.7 mmol, 4.0 molar amounts) in N,N-dimethylformamide (5 ml). The reaction solution was stirred at room temperature for two hours. The reaction solution was diluted with water and extracted with ethyl acetate. The organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was purified by thick column chromatography (eluent: petroleum ether/ethyl acetate/ammonia water = 1/10/1 drop) to give a yellow solid 2-(2-methoxy-5-(methylsulfonyl)pyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (44 mg, 45.8% yield). LCMS (ESI): m/z=523[M+1] ⁺ . ¹ H NMR(500MHz,MeOD)δ8.81(s,2H),8.70(dd,J＝28.5,23.2Hz,1H),7.92(d,J＝60.3Hz,1H),7.34–7.22(m,1H),6.97(dd,J＝15.9,7.4Hz,1H),4.02(s, 3H),3.95–3.80(m,1H),3.76–3.39(m,4H),3.24–3.15(m,3H),2.84(d,J＝ 15.8Hz,2H),2.58(d,J＝5.9Hz,3H),2.23–1.78(m,4H),1.61–1.47(m,3H).

Example 11: Preparation of 2-(2-methoxy-5-(methylsulfonyl)pyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propane-1-thione (Compound 70) (Prepared according to Scheme 5)

A mixture of 2-(2-methoxy-5-(methylsulfonyl)pyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3'-dihydro-1'-pyrrolidin-3,2'-[1,8]naphthyridine)-1-yl)propan-1-one (0412-31) (15 mg, 0.03 mmol, 1.0 eq) and Lawesson's reagent (17 mg, 0.04 mmol, 1.2 eq) in toluene (1 ml) was stirred in a microwave reactor at 125° C. for 1 hour. The reaction solution was diluted with water, extracted with ethyl acetate, and the organic phase was dried and concentrated under reduced pressure to obtain a crude oil. The crude product was purified by thick column chromatography (eluent: dichloromethane/methanol = 10/1) to give 2-(2-methoxy-5-(methylsulfonyl)pyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propane-1-thione (9 mg, yield 60%). LCMS (ESI): m/z = 539 [M+1] ⁺ . ¹ H NMR (500 MHz, CDCl ₃ )δ8.76–8.63(m,2H),8.02–7.81(m,1H),7.17(s,1H),7.11–7.00(m,1H),6.90(dd,J ＝20.4,4.6Hz,1H),5.35–5.00(m,1H),4.46–3.97(m,2H),3.94(d,J＝13.1Hz,3H),3.9 1–3.51(m,2H),3.04(dd,J＝28.4,7.2Hz,3H),2.80(t,J＝10.7Hz,2H),2.64(dd,J＝16 .3,9.1Hz,3H),2.37–2.07(m,2H),1.99(dd,J＝32.6,16.3Hz,2H),1.55–1.46(m,3H).

Example 12: 2-(5-fluorobenzofuran-6-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine Preparation of 3,2'-[1,8]naphthyridin-1-yl)propan-1-one (Compound 14)

Step 12a: Preparation of 4-fluoro-2-iodo-5-methylphenol: A mixture of 4-fluoro-3-methylphenol (5.0 g, 39.6 mmol, 1.0 eq.), p-toluenesulfonic acid monohydrate (7.5 g, 39.6 mmol, 1.0 eq.) and N-iodosuccinimide (9.8 g, 43.6 mmol, 1.1 eq.) in acetonitrile (50 ml) was stirred at room temperature for 2 hours. The reaction solution was quenched with sodium sulfite solution and extracted with ethyl acetate. The organic layer was washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 1/0 to 10/1) to give 4-fluoro-2-iodo-5-methylphenol (7.65 g, yield: 75.6%) as a yellow oil.

Step 12b: Preparation of 4-fluoro-5-methyl-2-((trimethylsilyl)ethynyl)phenol: To a mixture of 4-fluoro-2-iodo-5-methylphenol (4.19 g, 16.7 mmol, 1.0 eq), bistriphenylphosphine palladium dichloride (292 mg, 0.42 mmol, 0.025 eq) and cuprous iodide (79.3 mg, 0.42 mmol, 0.025 eq) in triethylamine/tetrahydrofuran (3.6 ml/5 ml) was added ethynyltrimethylsilane (8.2 g, 83 mmol, 5.0 eq) under nitrogen, and the mixture was stirred at 90° C. for four hours. The reaction solution was cooled to room temperature, diluted with water, and extracted with ethyl acetate. The organic phase was washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to give 4-fluoro-5-methyl-2-((trimethylsilyl)ethynyl)phenol (crude product) as a yellow oil.

Step 12c: Preparation of 5-fluoro-6-methylbenzofuran: A solution of 4-fluoro-5-methyl-2-((trimethylsilyl)ethynyl)phenol (crude), cuprous iodide (3.59 g, 18.9 mmol, 1.0 eq.) and N,N-diisopropylethylamine (4.9 g, 37.7 mmol, 2.0 eq.) in methanol (40 ml) was heated to 60°C and stirred for 3 hours. After cooling to room temperature, the reaction was diluted with water and extracted with ethyl acetate, and the organic layer was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was dissolved in tetrahydrofuran, and tetrabutylammonium fluoride trihydrate (6 g, 20.8 mol, 1.1 eq.) was added to the solution, and the mixture was stirred at room temperature for 1 hour. The reaction solution was diluted with water and extracted with ethyl acetate, and the organic layer was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: petroleum ether) to give 5-fluoro-6-methylbenzofuran (1.5 g, yield: 60%) as a yellow oil.

Step 12d: Preparation of 6-(bromomethyl)-5-fluorobenzofuran: Under nitrogen protection, 5-fluoro-6-methylbenzofuran (1.5 g, A mixture of 1,4-dichloro-2-nitropropane (2,6-dichloro-2-nitropropane (2,6-dichloro-2-nitropropane (3,6-dichloro-2-nitropropane (1,6-dichloro-2-nitropropane (2,6-dichloro-2-nitropropane (1,6-dichloro-2-nitropropane (2,6-dichloro-2-nitropropane (1,6-dichloro-2-nitropropane (2,6-dichloro-2-nitropropane (1,6-dichloro-2-nitropropane (2,6-dichloro-2-nitropropane (1,6-dichloro-2-nitropropane (2,6-dichloro-2-nitropropane (1,6-dichloro-2-nitropropane (2,6-dichloro-2-nitropropane (1,6-dichloro-2-nitropropane (

Step 12e: Preparation of 2-(5-fluorobenzofuran-6-yl)acetonitrile: Under nitrogen protection, a mixture of 6-(bromomethyl)-5-fluorobenzofuran (2 g, 8.7 mmol, 1.0 eq), trimethylsilyl nitrile (1.7 g, 17.4 mmol, 2.0 eq), tetrabutylammonium fluoride in tetrahydrofuran (17 ml, 17.4 mmol, 2.0 eq) and potassium carbonate (1.1 g, 8.7 mmol, 1.0 eq) in tetrahydrofuran (20 ml) was stirred at 60° C. overnight. The reaction solution was diluted with water and extracted with ethyl acetate, and the organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure to obtain 2-(5-fluorobenzofuran-6-yl)acetonitrile (crude product) as a yellow oil.

Step 12f: Preparation of 2-(5-fluorobenzofuran-6-yl)acetic acid: A mixture of 2-(5-fluorobenzofuran-6-yl)acetonitrile (crude product) and potassium hydroxide (2.4 g, 43.5 mmol, 5 equivalents) in ethanol/water = 1/1 (5 ml/5 ml) was stirred at 90°C overnight. The reaction solution was cooled to room temperature, diluted with water and extracted with ethyl acetate. The aqueous phase was adjusted to pH 2-3 with dilute sulfuric acid solution and extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was chromatographed on a silica gel column (eluent: ethyl acetate) to obtain 2-(5-fluorobenzofuran-6-yl)acetic acid (210 mg, yield 21%) as a yellow solid. MS (ES+): m/z = 193 (M+H)+.

Step 12g: Preparation of 2-(5-fluorobenzofuran-6-yl)propanoic acid: Under nitrogen, n-butyl lithium (1.38 ml, 2.06 mmol, 2.0 eq) was added to a solution of 2-(5-fluorobenzofuran-6-yl)acetic acid (210 mg, 1.03 mmol, 1.0 eq) in tetrahydrofuran (5 ml) at -70°C, and the mixture was stirred at -70°C for 30 minutes. Diisopropylamine (21.9 mg, 0.22 mmol, 0.2 eq) was then added and stirred for 15 minutes. Methyl iodide (307 mg, 2.2 mmol, 2.0 eq) was then added at -30°C, and the mixture was stirred at room temperature for 10 minutes. The reaction solution was diluted with water and extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure to obtain a yellow oily substance, 2-(5-fluorobenzofuran-6-yl)propanoic acid (20 mg, yield 8.8%). MS (ES+): m/z=209 (M+H)+.

Step 12h: Preparation of 2-(5-fluorobenzofuran-6-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 14): To 2-(5-fluorobenzofuran-6-yl)propanoic acid (20 mg, 0.096 mmol, 1.0 equiv), 7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (47.5 mg, 0.12 mmol, 1.3 eq.) was added to a mixture of -1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (0122-1) (34 mg, 0.096 mmol, 1.0 eq.) and N,N-diisopropylethylamine (50 mg, 0.38 mmol, 4.0 eq.) in N,N-dimethylformamide (5 ml). The mixture was stirred at room temperature for two hours. The reaction solution was diluted with water and extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was chromatographed on a thick column (eluent: petroleum ether/ethyl acetate/ammonia water = 1/100/1) to give a yellow solid 2-(5-fluorobenzofuran-6-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (22 mg, yield 47.2%). MS (ES+): m/z＝486(M+H)+.1H NMR(500MHz,MeOD)δ8.80(s,2H),7.79(t,J＝22.6Hz,2H),7.36(dd,J＝38.6,33.6Hz,3H),6.79(d,J＝44.9Hz,1H),4.31(d,J＝53 .9Hz,1H),3.69–3.43(m,4H),2.81(d,J＝3.9Hz,2H),2.61–2.43(m,3H),1.99(dd,J＝60.7,30.0Hz,4H),1.47(d,J＝5.6Hz,3H).

Example 13: Preparation of 6-methoxy-4-(1-(S)-7'-methyl-6'(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)-1-thiopropane-2-yl)nicotinonitrile (Compound 11) (Prepared according to Schemes 4 and 5)

Step 13a: Preparation of methyl 2-(5-bromo-2-methoxypyridin-4-yl)acetate (Compound 0409-11): Under nitrogen, lithium diisopropylamide in tetrahydrofuran (0.9 mol, 67 ml, 60.00 mmol, 3.0 eq) was added dropwise to a solution of 5-bromo-2-methoxy-4-methylpyridine (0408-11) (4.04 g, 20.00 mmol, 1.0 eq) in tetrahydrofuran (40 ml) at -30°C. After the reaction mixture was stirred at -30°C for 1 hour, dimethyl carbonate (5.40 g, 60.00 mmol, 3.0 eq) was added dropwise. At the end of the addition, the reaction mixture was warmed to room temperature and stirred for 1 hour. The reaction was quenched with 0.5 mol hydrochloric acid solution (120 ml, 60.00 mmol) and extracted with ethyl acetate. The organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by silica gel column chromatography (eluent: petroleum ether to petroleum ether/ethyl acetate = 20/1) to obtain a yellow oily product, methyl 2-(5-bromo-2-methoxypyridin-4-yl)acetate (3.84 g, yield: 73.82%). LCMS (ESI): m/z = 260 (M+H) ⁺ .

Step 13b: Preparation of methyl 2-(5-cyano-2-methoxypyridin-4-yl)propanoate (compound 0410-11): Under nitrogen, a solution of methyl 2-(5-bromo-2-methoxypyridin-4-yl)acetate (0409-11) (3.71 g, 14.27 mmol, 1.0 eq) in tetrahydrofuran (60 ml) at -70°C was added with lithium bis(trimethylsilyl)amide (1 mol per liter, 16 ml, 15.98 mmol, 1.12 eq) and stirred for 1 hour. A solution of iodomethane (2.23 g, 15.70 mmol, 1.1 eq) in tetrahydrofuran (5 ml) was added dropwise to the reaction mixture and stirred at -70°C for 2 hours. The reaction was quenched with saturated ammonium chloride solution, extracted with ethyl acetate, and the organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by silica gel column chromatography (eluent: petroleum ether to petroleum ether/ethyl acetate = 35/1) to give a yellow oily product, methyl 2-(5-bromo-2-methoxypyridin-4-yl)propanoate (3.38 g, yield: 86.45%). LCMS (ESI): m/z = 274 (M+H) ⁺ . A mixture of methyl 2-(5-bromo-2-methoxypyridin-4-yl)propanoate (1.37 g, 5.00 mmol, 1.0 eq.) and cuprous cyanide (2.68 g, 30.00 mmol, 6.0 eq.) in N-methylpyrrolidone (15 ml) was stirred at 180° C. for 1.5 hours. After cooling to room temperature, the reaction was quenched with water and extracted with ethyl acetate. The organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 30/1 to 10/1) to give yellow oily product methyl 2-(5-cyano-2-methoxypyridin-4-yl)propanoate (434 mg, yield: 39.45%). LCMS (ESI): m/z = 221 (M+H) ⁺ .

Step 13c: Preparation of 2-(5-cyano-2-methoxypyridin-4-yl)propanoic acid (compound 0405-11): Under nitrogen protection, a mixture of methyl 2-(5-cyano-2-methoxypyridin-4-yl)propanoate (0410-11) (434 mg, 1.97 mmol, 1.0 equiv) and potassium trimethylsilanol (380 mg, 2.96 mmol, 1.5 equiv) in tetrahydrofuran (5 ml) was stirred at room temperature for 1 hour. The reaction mixture was quenched with a 1 mol/L hydrochloric acid solution and extracted with ethyl acetate. The organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 5/1 to ethyl acetate) to obtain a yellow solid product 2-(5-cyano-2-methoxypyridin-4-yl)propanoic acid (269 mg, yield: 66.42%). LCMS (ESI): m/z = 207 (M+H) ⁺ .

Step 13d: Preparation of 6-methoxy-4-(1-(S)-7'-methyl-6'(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidin-3,2'-[1,8]naphthyridin]-1-yl)-1-oxopropan-2-yl)nicotinonitrile (Compound 0412-11): 2-(5-cyano-2-methoxypyridin-4-yl)propanoic acid (0405-11) (20.6 mg, 0.10 mmol, 1.0 equiv), (S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidin-3,2'-[1,8]naphthyridin]-1-yl)-1-oxopropan-2-yl)nicotinonitrile (Compound 0412-11) A mixture of 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (40 mg, 0.105 mmol, 1.05 eq) in dichloromethane (2 ml) was stirred for 30 minutes. The mixture was diluted with water and extracted with dichloromethane, and the organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by preparative thin layer chromatography (eluent: dichloromethane/methanol=20/1) to give a white solid product, 6-methoxy-4-(1-(S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridin]-1-yl)-1-oxopropan-2-yl)nicotinonitrile (45 mg, yield: 95.74%). LCMS (ESI): m/z=470 (M+H) ⁺ .

Step 13e: Preparation of 6-methoxy-4-(1-(S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidin-3,2'-[1,8]naphthyridin]-1-yl)-1-thiopropane-2-yl)nicotinonitrile (Compound 11): 6-methoxy-4-(1-(S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidin-3,2'-[1,8]naphthyridin]-1-yl)-1-thiopropane-2-yl)nicotinonitrile (Compound 11) A mixture of 4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridin]-1-yl)-1-oxopropan-2-yl)nicotinonitrile (0412-11) (19.7 mg, 0.042 mmol, 1.0 eq) and Lawesson's reagent (20.4 mg, 0.05 mmol, 1.2 eq) in toluene (1.5 ml) was stirred in a microwave reactor at 125° C. for 40 minutes. The mixture was diluted with water and extracted with ethyl acetate, and the organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by preparative thin layer chromatography (eluent: dichloromethane/methanol=20/1) to give a yellow solid product, 6-methoxy-4-(1-(S)-7'-methyl-6'(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridin]-1-yl)-1-thiopropane-2-yl)nicotinonitrile (13 mg, yield: 63.73%). LCMS (ESI): m/z=486 (M+H) ⁺ . ^1H NMR(500MHz,MeOD)δ8.72(t,J＝5.4Hz,2H),8.32(dd,J＝36.1,30.8Hz,1H),7.7 8(d,J＝6.3Hz,1H),7.22(q,J＝5.0Hz,1H),6.89(dd,J＝26.3,11.2Hz,1H),4.49( dd,J＝28.2,6.7Hz,1H),4.09–3.74(m,7H),2.85–2.69(m,2H),2.51–2.42(m,3 H),2.31–2.00(m,2H),1.87(ddd,J＝20.0,14.3,7.4Hz,2H),1.58–1.46(m,3H).

Example 14: Preparation of (S)-N-(3,4-difluorophenyl)-N,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-thiocarboxamide (Compound 4) (prepared according to Scheme 3):

Under nitrogen protection, to a mixture of 3,4-difluoro-N-methylaniline (0204-3) (14 mg, 0.10 mmol, 1.0 eq.), triethylamine (60.6 mg, 0.60 mmol, 6.0 eq.) in dichloromethane (3 ml) was added dropwise carbon dichloride (11.5 mg, 0.10 mmol, 1.0 eq.), and the mixture was stirred at room temperature for one hour. The mixture was quenched with 1M hydrochloric acid solution, Dilute with water and extract with dichloromethane. Wash the organic phase with saturated brine, dry over anhydrous sodium sulfate and concentrate. The residue (crude product) is used directly in the next step without further purification.

Under nitrogen protection, to a mixture of (S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine](0122-1) (31.7 mg, 0.09 mmol, 0.9 eq) and triethylamine (60.6 mg, 0.60 mmol, 6.0 eq) in dichloromethane (2 ml) was added (3,4-difluorophenyl)(methyl)aminothioyl chloride (crude), and the mixture was stirred at room temperature for one hour. The mixture was diluted with water and extracted with dichloromethane, and the organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by thick preparative thin layer chromatography (eluent: dichloromethane/methanol/aqueous ammonia = 80/3.5/0.8) to give a yellow solid product (S)-N-(3,4-difluorophenyl)-N,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carbothioamide (30 mg, yield: 64.38%). LCMS (ESI): 467 [M+H] ⁺ . ^1H NMR(500MHz,MeOD)δ8.79(t,J＝5.3Hz,2H),7.87–7.52(m,3H),7.50–7.36(m,1H),7.31–7.09(m,2H),6.77(dd,J＝45.1,2.5Hz,1H ),4.14–3.94(m,1H),3.93–3.37(m,4H),2.90–2.67(m,2H),2.53(dd,J＝34.4,13.4Hz,4H),2.21–1.65(m,4H),1.50–1.40(m,3H).

Example 15: Preparation of 2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one-2-deuterium (Compound 67) (Prepared according to Schemes 4 and 5)

Step 15a: Preparation of methyl 2-(5-fluoro-2-methoxypyridin-4-yl)propanoate (Compound 0410-67)

Under nitrogen protection, oxalyl chloride (1.5 ml, 1M dichloromethane solution, 1.5 mmol, 1.5 eq) was added dropwise to a solution of 2-(5-fluoro-2-methoxypyridin-4-yl)propionic acid (0405-7) (200 mg, 1.0 mmol, 1.0 eq) and N,N-dimethylformamide (two drops) in dichloromethane (5 ml) at -78°C, and the mixture was stirred at -78°C for 1.0 hour. Methanol (0.5 ml) was then added dropwise to the reaction solution, and the mixture was stirred at room temperature for 1 hour. The mixture was washed with water and saturated brine. The organic phase was dried over anhydrous sodium sulfate and concentrated. The residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 4/1 to 1/2) to give methyl 2-(5-fluoro-2-methoxypyridin-4-yl)propanoate (177 mg, yield: 82.7%) as a yellow oil.

Step 15b: Preparation of 2-deuterium-2-(5-fluoro-2-methoxypyridin-4-yl)propionic acid (Compound 0405-67): Under nitrogen protection, lithium bis(trimethylsilyl)amide (0.35 ml, 1M tetrahydrofuran solution, 0.35 mmol, 1.4 eq.) was added dropwise to a solution of methyl 2-(5-fluoro-2-methoxypyridin-4-yl)propanoate (0410-67) (50 mg, 0.23 mmol, 1.0 eq.) in tetrahydrofuran (5 ml) at -78°C, and the mixture was stirred at -78°C for 1.0 hour. Heavy water (0.2 ml) was then added dropwise to the reaction solution, and the mixture was stirred at room temperature overnight. The mixture was diluted with methyl tert-butyl ether and washed with water. The aqueous phase was acidified with 1M hydrochloric acid, extracted with ethyl acetate, and washed with water and saturated brine. The organic phase was dried over anhydrous sodium sulfate and concentrated to give 2-deuterio-2-(5-fluoro-2-methoxypyridin-4-yl)propanoic acid (50 mg, crude) as a yellow oil.

Step 15c: Preparation of 2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one-2-deuterium (Compound 67): Under nitrogen protection, at 0°C, add (S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl [1,8]naphthyridine] (0122-1) (50 mg, 0.14 mmol, 1.0 eq), 2-deuterium-2-(5-fluoro-2-methoxypyridin-4-yl) propionic acid (0405-67) (23 mg, 0.14 mmol, 1.00 eq) and N,N-diisopropylethylamine (55 mg, 0.42 mmol, 1.05 eq) in acetonitrile (5 ml) were added N'N-carbonyldiimidazole (25 mg, 0.15 mmol, 1.1 eq). The mixture was stirred at room temperature overnight, then diluted with ethyl acetate, washed with water and saturated brine. The organic phase was dried over anhydrous sodium sulfate and concentrated. The residue was purified by preparative thin layer chromatography (eluent: petroleum ether/ethyl acetate = 1/1) to give a white solid product, 2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one-2-deuterium (47.6 mg, yield: 72.6%), LCMS (ESI): m/z = 454 [M+1] ⁺ . ^1H NMR (500MHz, MeOD) δ8.81(t,J＝3.8Hz,2H),7.96(t,J＝20.7Hz,1H),7.84(d,J＝14.8Hz,1H),7.35–7.21(m,1H),6.83–6.67(m,1H),3.87( dd,J＝10.5,4.2Hz,3H),3.76–3.34(m,4H),2.92–2.72(m,2H),2.57(d,J＝12.7Hz,3H),2.19–1.74(m,4H),1.44(dt,J＝12.5,6.4Hz,3H).

Example 16: Preparation of 2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propane-1-thione-2-deuterium (Compound 75) (Prepared according to Scheme 5)

Under nitrogen protection, Lawesson's reagent (47 mg, 0.12 mmol, 1.2 eq.) was added to a toluene (2 ml) solution of 2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one-2-deuterium (Compound 67) (45 mg, 0.10 mmol, 1.0 eq.), and the mixture was heated to 100°C for overnight reaction. The mixture was diluted with ethyl acetate and washed with water and saturated brine. The organic phase was dried over anhydrous sodium sulfate and concentrated. The residue was purified by preparative thin layer chromatography (eluent: petroleum ether/ethyl acetate = 1/1) to give a white solid product, 2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propane-1-thione-2-deuterium (26.0 mg, yield: 55.7%), LCMS (ESI): m/z = 481 [M+1] ⁺ . ¹ HNMR(500MHz,MeOD)δ8.81(t,J＝4.6Hz,2H),7.98–7.74(m,2H),7.30(t,J＝3.9Hz,1H),6.97–6.80(m,1H),4.21–3.95(m,2H), 3.95–3.63(m,5H),2.95–2.67(m,2H),2.57(dd,J＝10.2,3.4Hz,3H),2.34–2.09(m,2H),2.08–1.85(m,2H),1.61–1.51(m,3H).

Example 17: Preparation of (2R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-(7'-(methyl-d3)-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 59) (Prepared according to Schemes 1 and 4)

Step 17a: Preparation of 2-chloro-6-(methyl-d3)pyridin-3-amine 2-chloro-6-(methyl-d3)pyridin-3-amine (Compound 0106-59):

Under nitrogen protection, sodium hydride (2.41 g, 60.25 mmol, 2.5 eq) was added to a solution of 6-bromo-2-chloropyridin-3-amine (5.00 g, 24.10 mmol, 1.0 eq) in N,N-dimethylformamide (25 ml) at 0°C, and the reaction solution was stirred at 0°C for one hour. 4-Methoxybenzyl chloride (7.93 g, 50.61 mmol, 2.1 eq) was added to the reaction mixture at 0°C and stirred at room temperature for 1 hour. The reaction was quenched with ammonium chloride solution, diluted with water, and extracted with ethyl acetate. The organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 5/1) to give a yellow solid product 6-bromo-2-chloro-N,N-bis(4-methoxybenzyl)pyridin-3-amine (11 g, yield: 100%). LCMS (ESI): m/z = 447 [M+H] ⁺ .

Under nitrogen protection, tert-butyl lithium (1.3M, 51.69 ml, 67.20 mmol, 1.5 eq) was added dropwise to a solution of 6-bromo-2-chloro-N,N-bis(4-methoxybenzyl)pyridin-3-amine (19.98 g, 44.80 mmol, 1.0 eq) in tetrahydrofuran (200 ml) at -70°C and stirred for 1 hour. A solution of dry iodomethane (9.74 g, 67.20 mmol, 1.5 eq) in tetrahydrofuran (10 ml) was added to the reaction mixture at -70°C and stirred overnight at room temperature. The reaction was quenched with saturated ammonium chloride solution, diluted with water, extracted with ethyl acetate, and the organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 30/1 to 10/1) to give a yellow oily product 2-chloro-N,N-bis(4-methoxybenzyl)-6-(methyl-d3)pyridin-3-amine (9.0 g, yield: 52.05%). LCMS (ESI): m/z = 386 [M+H] ⁺ .

Trifluoroacetic acid (20 ml) was added to a mixture of 2-chloro-N, N-bis(4-methoxybenzyl)-6-(methyl-d3)pyridine-3-amine (9.0 g, 23.32 mmol, 1.0 eq.) in dichloromethane (80 ml), and stirred overnight at room temperature. The solvent was removed under vacuum. The pH of the residue was adjusted to 13 with a 2M sodium hydroxide solution. The mixture was extracted with dichloromethane, and the organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 5/1) to give a yellow oily product, 2-chloro-6-(methyl-d3)pyridine-3-amine (3.38 g, yield: 100%). LCMS (ESI): m/z = 146 [M+H] ⁺ .

Step 17b: Preparation of 2-chloro-3-iodo-6-(methyl-d3)pyridine (Compound 0107-59): To a solution of 2-chloro-6-(methyl-d3)pyridin-3-amine (0106-59) (3.38 g, 23.32 mmol, 1.0 eq) in concentrated hydrochloric acid/water (25 ml/25 ml) was added 24 ml of sodium nitrite solution (2.41 g. 34.98 mmol, 1.5 eq) and stirred at 0°C for 30 minutes. Methyl tert-butyl ether (15 ml) was then added to the reaction and 80 ml of potassium iodide solution (7.74 g, 46.64 mmol, 2.0 eq) was added dropwise at 0°C. The mixture was stirred at room temperature overnight. The reaction was quenched with sodium sulfite solution. The pH of the residue was adjusted to 7 with 2M sodium hydroxide solution. The mixture was extracted with ethyl acetate, and the organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 40/1) to give a yellow solid product 2-chloro-3-iodo-6-(methyl-d3)pyridine (4.68 g, yield: 72.24%).

Step 17c: Preparation of tert-butyl 3-hydroxy-3-((trimethylsilyl)ethynyl)pyrrolidine-1-carboxylate (Compound 0102-59): Under nitrogen protection, to a solution of ethynyltrimethylsilane (2.55 g, 25.9 mmol, 1.2 eq) in tetrahydrofuran (40 ml) was added dropwise n-butyllithium (9.5 ml, 23.8 mmol, 1.1 eq) at -70 °C, and the mixture was stirred at -70 °C for 1.0 hour. Then, a solution of 1-tert-butyloxycarbonyl-3-pyrrolidone (0101-59) (4.0 g, 21.6 mmol, 1.0 equivalent) in tetrahydrofuran (10 ml) was added dropwise to the reaction solution at -60°C, the cryogenic device was removed, and the mixture was stirred overnight. The reaction solution was quenched with ammonium chloride solution and extracted with ethyl acetate, and the organic phase was dried and concentrated under reduced pressure to give a yellow oily crude product of tert-butyl 3-hydroxy-3-((trimethylsilyl)ethynyl)pyrrolidine-1-carboxylate (6.04 g), which was used directly in the next step without further purification.

Step 17d: Preparation of tert-butyl 3-ethynyl-3-hydroxypyrrolidine-1-carboxylate (Compound 0103-59): Under nitrogen protection, potassium carbonate (5.80 g, 42.3 mmol, 2.0 eq.) was added to a solution of tert-butyl 3-hydroxy-3-((trimethylsilyl)ethynyl)pyrrolidine-1-carboxylate (0102-59) (6.00 g, 21.2 mmol, 1.0 eq.) in methanol (100 ml), and the mixture was stirred at room temperature for 1.5 hours. The solvent was removed under reduced pressure, the residue was diluted with water and extracted with ethyl acetate, and the organic phase was dried and concentrated under reduced pressure. The residue was purified by silica gel column (petroleum ether/ethyl acetate=10/1) to obtain a yellow oily product, tert-butyl 3-ethynyl-3-hydroxypyrrolidine-1-carboxylate (4.43 g, two-step yield: 97.1%).

Step 17e: Preparation of tert-butyl 3-ethynyl-3-hydroxypyrrolidine-1-carboxylate (0104-59): Under nitrogen protection, acetyl chloride (1.98 g, 25.2 mmol, 1.2 eq) was added to a solution of tert-butyl 3-ethynyl-3-hydroxypyrrolidine-1-carboxylate (0103-59) (4.43 g, 21.0 mmol, 1.0 eq) and N,N-diisopropylethylamine (4.06 g, 31.5 mmol, 1.5 eq) in dichloromethane (100 ml) at 0° C. The mixture was stirred at 0° C. for 1 hour. The reaction solution was quenched with water and extracted with dichloromethane, and the organic phase was dried and concentrated under reduced pressure. The residue was purified by silica gel column (petroleum ether/ethyl acetate=20/1 to 5/1) to give yellow oily product tert-butyl 3-ethynyl-3-hydroxypyrrolidine-1-carboxylate (3.07 g, yield: 57.8%).

Step 17f: Preparation of tert-butyl 3-ethynyl-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (Compound 0105-59): Under nitrogen protection, a solution of tert-butyl 3-ethynyl-3-hydroxypyrrolidine-1-carboxylate (0104-59) (2.83 g, 11.2 mmol, 1.0 eq) in tetrahydrofuran (10 ml) was added to a solution of 4-methoxybenzylamine (3.07 g, 22.3 mmol, 2.0 eq) and cuprous chloride (111 mg, 1.1 mmol, 0.1 eq) in tetrahydrofuran (30 ml) at 70° C. The mixture was stirred at 70° C. for 1 hour. The reaction solution was diluted with water and extracted with ethyl acetate, and the organic phase was dried and concentrated under reduced pressure. The residue was purified by silica gel column (petroleum ether/ethyl acetate=10/1 to 4/1) to give yellow oily product tert-butyl 3-ethynyl-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (2.56 g, yield: 69.4%).

Step 17g: Preparation of tert-butyl 3-((2-chloro-6-(methyl-d3)pyridin-3-yl)ethynyl)-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (Compound 0108-59): Under nitrogen protection, 2-chloro-3-iodo-6-(methyl-d3)pyridine (0107-59) (1.30 g, 5.07 mmol, 1.0 equiv), 3-ethynyl -3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylic acid tert-butyl ester (0105-59) (1.69 g, 5.07 mmol, 1.0 eq), cuprous iodide (96 mg, 0.51 mmol, 0.1 eq) and [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride (356 mg, 0.51 mmol, 0.1 eq) were stirred at 90 ° C for 4 hours. The mixture was diluted with water and extracted with ethyl acetate. The organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 10/1 to 3/1) to give a yellow oily product 3-((2-chloro -6-(methyl-d3)pyridin-3-yl)ethynyl)-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylic acid tert-butyl ester (1.90 g, yield: 81.90%). LCMS (ESI): m/z=459 [M+H] ⁺ .

Step 17h: Preparation of tert-butyl 3-(2-(2-chloro-6-(methyl-d3)pyridin-3-yl)ethyl)-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (Compound 0109-59): A mixture of tert-butyl 3-((2-chloro-6-(methyl-d3)pyridin-3-yl)ethynyl)-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (0108-59) (1.90 g, 4.126 mmol, 1.0 eq), platinum dioxide (187 mg, 0.825 mmol, 0.2 eq) in methanol (20 ml) was stirred at room temperature overnight under a hydrogen atmosphere. The mixture was filtered through celite, the filter cake was washed with methanol, and the filtrate was concentrated. The residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 5/1 to 3/1) to give yellow oily product tert-butyl 3-(2-(2-chloro-6-(methyl-d3)pyridin-3-yl)ethyl)-3-(((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (1.30 g, yield: 68.42%). LCMS (ESI): m/z = 463 [M+H] ⁺ .

Step 17i: Preparation of tert-butyl 1'-(4-methoxybenzyl)-7'-(methyl-d3)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (Compound 0110-59): Under nitrogen protection, tert-butyl 3-(2-(2-chloro-6-(methyl-d3)pyridin-3-yl)ethyl)-3-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate A mixture of butyl ester (0109-59) (1.30 g, 2.81 mmol, 1.0 eq.), palladium acetate (63 mg, 0.28 mmol, 0.1 eq.), 2-dicyclohexylphosphine-2',6'-diisopropoxy-1,1'-biphenyl (262 mg, 0.56 mmol, 0.2 eq.) and sodium tert-butoxide (540 mg, 5.62 mmol, 2.0 eq.) was stirred in a microwave apparatus for 1 hour. The mixture was diluted with water and extracted with ethyl acetate, and the organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 5/1 to 3/1) to give a yellow oily product, 1'-(4-methoxybenzyl)-7'-(methyl-d3)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (945 mg, yield: 78.95%). LCMS (ESI): m/z = 427M+H] ⁺ .

Step 17j: Preparation of tert-butyl 7'-(methyl-d3)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (Compound 0112-59): To a mixture of tert-butyl 1'-(4-methoxybenzyl)-7'-(methyl-d3)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (0110-59) (945 mg, 2.22 mmol, 1.0 eq) in dichloromethane (8 mL) was added trifluoroacetic acid (4 mL) and stirred at room temperature for 4 hours. The solvent was removed under vacuum and the pH of the residue was adjusted to 8 with sodium bicarbonate solution. A solution of di-tert-butyl dicarbonate (485 mg, 2.22 mmol, 1.0 eq) in tetrahydrofuran (5 mL) was added and stirred at room temperature for 3 hours. The mixture was diluted with water and extracted with ethyl acetate, and the organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by silica gel column chromatography (eluent: dichloromethane to dichloromethane/methanol = 10/1) to obtain a yellow oily product 7'-(methyl-d3)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (580 mg, yield: 85.46%). LCMS (ESI): m/z = 307 [M+H] ⁺ .

Step 17k: Preparation of tert-butyl 6'-bromo-7'-(methyl-d3)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (Compound 0115-59): Under nitrogen protection, 1,3-dibromo-5,5-dimethylhydantoin (309 mg, 1.08 mmol, 0.6 eq) was added to a solution of tert-butyl 7'-(methyl-d3)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (0112-59) (550 mg, 1.80 mmol, 1.0 eq) in dichloromethane (10 ml) and stirred at 0°C for 30 minutes. The reaction was stirred with 2% thiocyanate. The mixture was quenched with sodium sulfate solution. The mixture was diluted with water and extracted with ethyl acetate, and the organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by silica gel column chromatography (eluent: dichloromethane/methanol=50/1 to 30/1) to give a yellow solid product 6'-bromo-7'-(methyl-d3)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (720 mg, yield: 100%). (ESI): m/z=386[M+H] ⁺ .

Step 171: Preparation of (1-(tert-butyloxycarbonyl)-7'-(methyl-d3)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-6'-yl)boronic acid (Compound 0117-59): Under nitrogen protection, 6'-bromo-7'-(methyl-d3)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (0115-59) (690 mg, 1.79 mmol, 1.0 equiv), tetrahydroxydiboron ( A mixture of 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (26 mg, 0.054 mmol, 0.03 eq.), potassium acetate (439 mg, 4.48 mmol, 2.5 eq.) and sodium tert-butoxide (4.3 mg, 0.045 mmol, 0.025 eq.) in methanol/ethylene glycol (20 ml/1 ml) was stirred at 55° C. for 1 hour. The mixture was diluted with water and extracted with dichloromethane, and the organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by silica gel column chromatography (eluent: dichloromethane/methanol=30/1 to 10/1) to give a yellow oily product (1-(tert-butyloxycarbonyl)-7'-(methyl-d3)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridin]-6'-yl)boronic acid (360 mg, yield: 57.46%). LCMS (ESI): m/z=351M+H] ⁺ .

Step 17m: Preparation of (7'-(methyl-d3)-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (Compound 0119-59): Under nitrogen protection, (1-(tert-butyloxycarbonyl)-7'-(methyl-d3)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester 2-(2-(2-(2-(2-(2-nitro-3,2'-[1,8]naphthyridin]-6'-yl)boronic acid (0117-59) (360 mg, 1.03 mmol, 1.0 equiv), 2-bromopyrimidine (213 mg, 1.34 mmol, 1.3 equiv), Xphos-Pd-G2 (30 mg, 0.036 mmol, 0.02 equiv), 2-dicyclohexylphosphino-2',4',6'-triisopropylamine A mixture of propylbiphenyl (15 mg, 0.031 mmol, 0.03 eq) and sodium carbonate (328 mg, 3.09 mmol, 3.0 eq) in toluene/ethanol/water (4 ml/2 ml/2 ml) was stirred at 60°C for 1 hour. The mixture was diluted with water and extracted with ethyl acetate, and the organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by silica gel column chromatography (eluent: dichloromethane/methanol = 40/1 to 20/1) to give tert-butyl 7'-(methyl-d3)-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (290 mg, yield: 73.42%). LCMS (ESI): m/z = 385 [M+H] ⁺ .

Step 17n: Preparation of (methyl-d3)-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (Compound 0121-59): A solution of tert-butyl 7'-(methyl-d3)-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (77 mg, 0.20 mmol, 1.0 eq) in hydrogen chloride-methanol (2 mL) was stirred at room temperature for 2 hours. The solvent was removed under vacuum. The residue was used in the next step without purification. (Crude) LCMS (ESI): m/z=285[M+H] ⁺ .

Step 17o: Preparation of (2R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-(7'-(methyl-d3)-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 59): To a mixture of (R)-2-(5-fluoro-2-methoxypyridin-4-yl)propanoic acid (0406-7) (40 mg, 0.20 mmol, 1.0 eq.) in acetonitrile (2 mL) was added pyridine trifluoromethanesulfonate (92 mg, 0.4 mmol, 2.0 eq) and N,N'-carbonyldiimidazole (36 mg, 0.22 mmol, 1.1 eq) were added and the mixture was stirred at room temperature for 1 hour. (Methyl-d3)-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (77 mg, 0.60 mmol, 3.0 eq) was added to the reaction mixture and stirred at room temperature for 3 hours. The mixture was diluted with water and extracted with ethyl acetate, and the organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by preparative thin layer chromatography (eluent: dichloromethane/methanol/aqueous ammonia=80/3.5/0.8) to give a white solid product (2R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-(7'-(methyl-d3)-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 59) (40 mg, yield: 43.01%). LCMS (ESI): m/z=466[M+H] ⁺ . ¹ HNMR(500MHz,MeOD)δ8.71(t,J＝3.8Hz,2H),7.81(dd,J＝75.5,11.1Hz,2H),7.24–7.13(m,1H),6.72–6.52(m,1H),4.22–3 .99(m,1H),3.77(t,J＝7.6Hz,3H),3.64–3.25(m,4H),2.85–2.38(m,2H),2.10–1.62(m,5H),1.35(dt,J＝12.9,6.8Hz,3H).

Example 18: Preparation of (R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7'-(methyl-d3)-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 101):

Compound 59 (31 mg) was separated by chiral HPLC (chromatographic column: ChiralPak AD-H, 10×250 mm). The first eluting enantiomer was a white solid product (R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-((S)-7'-(methyl-d3)-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 101) (19 mg, yield: 62.50%). LCMS (ESI): 466 [M+H] ⁺ . ^1H NMR (500MHz, DMSO) δ8.80(d,J＝2.6Hz,2H),8.11(d,J＝5.7Hz,1H),7.89(d,J＝11.6Hz,1H),7.23(d,J＝50.3Hz,2H),6.72(dd,J＝30.7,4 .6Hz,1H),4.12(dd,J＝26.8,6.9Hz,1H),3.83(s,3H),3.61–3.37(m,4H),2.85–2.59(m,2H),2.05–1.62(m,4H),1.33(t,J＝6.7Hz,3H).

Example 19: Preparation of 2-(5-fluorobenzofuran-6-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propane-1-thione (Compound 12) (prepared according to Scheme 5 route):

A mixture of 2-(5-fluorobenzofuran-6-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 14) (30 mg, 0.064 mmol, 1.0 eq) and Lawesson's reagent (49 mg, 0.12 mmol, 1.89 eq) in toluene (2 ml) was stirred and heated in a microwave at 125° C. for 1 hour. The reaction solution was diluted with water, extracted with ethyl acetate, and the organic phase was dried and concentrated under reduced pressure to obtain a crude oil. The crude product was purified by thick column chromatography (eluent: dichloromethane/methanol = 10/1) to give 2-(5-fluorobenzofuran-6-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propane-1-thione (17 mg, 54.8% yield). LCMS (ESI): m/z=488[M+1] ⁺ . ¹ H NMR(500MHz,MeOD)δ8.78–8.67(m,2H),7.85–7.62(m,2H),7.61–7.49(m,1H),7.31–6.97(m,2H),6.78–6.56(m,1H),4.56(d,J＝7.2H z,1H),3.93–3.61(m,4H),2.75(ddd,J＝19.9,14.6,5.6Hz,2H),2.57–2.41(m,3H),2.15–1.83(m,4H),1.51(dd,J＝12.8,6.5Hz,3H).

Example 20: Preparation of 2-(4-methoxybenzofuran-6-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 87):

Step 20a: Preparation of 4-bromo-2,6-dimethoxybenzaldehyde: Sodium methoxide (5.4 M methanol solution, 5.87 mL, 31.67 mmol, 2.0 eq.) was added to a mixture of 4-bromo-2,6-difluorobenzaldehyde (3.5 g, 15.84 mmol, 1.0 eq.) in methanol (20 mL). The mixture was heated to 65°C under nitrogen atmosphere for 3.5 hours. The solvent was removed under reduced pressure. The residue was diluted with water (60 mL) and then extracted with ethyl acetate (30 mL×3). The combined organic layers were washed with saturated brine (30 mL), dried over anhydrous sodium sulfate and concentrated. The residue was subjected to column chromatography on silica gel (petroleum ether: ethyl acetate 8:1) to give 4-bromo-2,6-dimethoxybenzaldehyde (2.89 g, yield: 74%) as a white solid. LCMS (ESI): m/z 245 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether:ethyl acetate=4:1).

Step 20b: Preparation of 4-bromo-2-hydroxy-6-methoxybenzaldehyde: To a mixture of aluminum chloride (3.54 g, 26.53 mmol, 1.0 eq.) and sodium iodide (3.98 g, 26.53 mmol, 2.0 eq.) in acetonitrile (16 ml) at 0°C was added dropwise a solution of 4-bromo-2,6-dimethoxybenzaldehyde (3.25 g, 13.27 mmol, 1.0 eq.) in dichloromethane (16 ml). The mixture was warmed to room temperature and then stirred for 4 hours. 1N dilute hydrochloric acid (50 ml) was added to quench the reaction. The aqueous layer was extracted with ethyl acetate (30 ml x 3). The combined organic layers were washed with saturated brine (30 ml), dried over anhydrous sodium sulfate and concentrated. The residue was separated by column chromatography on silica gel (petroleum ether: ethyl acetate 30:1) to give 4-bromo-2-hydroxy-6-methoxybenzaldehyde (2.87 g, yield: 94%) as a white solid. LCMS (ESI): m/z 231 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 20:1).

Step 20c: Preparation of 6-bromo-4-methoxybenzofuran: To a mixture of 4-bromo-2-hydroxy-6-methoxybenzaldehyde (2.87 g, 12.42 mmol, 1.0 eq.) and cesium carbonate (10.12 g, 31.05 mmol, 2.5 eq.) in N,N-dimethylformamide (20 ml) was added ethyl bromoacetate (2.49 g, 14.91 mmol, 1.2 eq.). The mixture was heated to 120°C under nitrogen atmosphere for 8 hours. The mixture was diluted with water (80 ml) and then extracted with ethyl acetate (20 ml x 3). The combined organic layer was washed with saturated brine (20 ml), dried over anhydrous sodium sulfate and concentrated. The residue was subjected to column chromatography on silica gel (petroleum ether: ethyl acetate 50:1) to give 6-bromo-4-methoxybenzofuran (0.492 g, yield: 17%) as a white solid. LCMS (ESI): m/z 227 [M+1] ⁺ ; TLC: Rf 0.8 (petroleum ether:ethyl acetate=10:1).

Step 20d: Preparation of tert-butyl 2-(4-methoxybenzofuran-6-yl)propanoate: To a mixture of 6-bromo-4-methoxybenzofuran (100 mg, 0.44 mmol, 1.0 eq), Pd(dba) ₂ (25 mg, 0.044 mmol, 0.1 eq) and X-Phos (42 mg, 0.088 mmol, 0.2 eq) in tetrahydrofuran (1 ml) was added (1-(tert-butyloxy)-1-oxopropan-2-yl)bromide. Zinc (0.96M tetrahydrofuran solution, 2 ml, 1.92 mmol, 4.4 eq). The mixture was heated to 65 ° C under a nitrogen atmosphere for 1.5 hours. The mixture was diluted with saturated ammonium chloride solution (20 ml) and then extracted with ethyl acetate (15 ml×3). The combined organic layer was washed with saturated brine (15 ml), dried over anhydrous sodium sulfate and concentrated. The residue was purified by preparative thin layer chromatography (petroleum ether: ethyl acetate = 50: 1) to give a light yellow oily substance tert-butyl 2-(4-methoxybenzofuran-6-yl) propionate (79 mg, yield: 65%). LCMS (ESI): m/z 277 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 50: 1).

Step 20e: Preparation of 2-(4-methoxybenzofuran-6-yl)propanoic acid: A mixture of tert-butyl 2-(4-methoxybenzofuran-6-yl)propanoate (70 mg, 0.254 mmol, 1.0 eq) in hydrogen chloride/dioxane solution (4M, 1 ml) was stirred at room temperature overnight. The solvent was removed under reduced pressure. The residue was dried under vacuum to give a pale yellow oil (2-(4-methoxybenzofuran-6-yl)propanoic acid (56 mg, crude). LCMS (ESI): m/z 221 [M+1] ⁺ ; TLC: Rf 0.3 (dichloromethane:methanol=10:1).

Step 20f: Preparation of 2-(4-methoxybenzofuran-6-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 87): 2-(4-methoxybenzofuran-6-yl)propanoic acid (23 mg, 0.105 mmol, 1.0 equiv), 2-(7-azobenzotriazole)-N,N,N',N'- To a mixture of tetramethyluronium hexafluorophosphate (42 mg, 0.11 mmol, 1.05 eq) and N,N-diisopropylethylamine (68 mg, 0.525 mmol, 5.0 eq) in dichloromethane (2.5 ml) was added (S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (0122-1) (37 mg, 0.105 mmol, 1.0 eq). The mixture was stirred at room temperature for 0.5 hours. The mixture was diluted with water (20 ml) and then extracted with ethyl acetate (10 ml x 3). The combined organic layer was washed with saturated brine (15 ml), dried over anhydrous sodium sulfate and concentrated. The residue was purified by preparative thin layer chromatography (dichloromethane:methanol:aqueous ammonia=80:3.5:0.8) to give a white solid mixture of two diastereoisomers 2-(4-methoxybenzofuran-6-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine- ^3,2 '-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 87) (34 mg, yield: 67%), NMR(500MHz,MeOD)δ8.81(dd,J＝7.3,4.8Hz,2H),7.82(d,J＝72.9Hz,1H),7.57(d,J＝56 .2Hz,1H),7.30(d,J＝3.9Hz,1H),7.07(dd,J＝25.2,11.8Hz,1H),6.89–6.61(m,2H),4. 03(dd,J＝25.4,19.3Hz,1H),3.91(dd,J＝30.5,17.0Hz,3H),3.75–3.36(m,4H),2.83(d ,J＝20.9Hz,2H),2.56(dd,J＝33.0,14.8Hz,3H),2.23–1.71(m,4H),1.50–1.42(m,3H).

Example 21: Preparation of (R)-2-(4-methoxybenzofuran-6-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 102):

Compound 87 diastereomers (20 mg) were separated using chiral HPLC (column: ChiralPak AD-H, 10×250 mm). The second eluting enantiomer was a white solid (R)-2-(4-methoxybenzofuran-6-yl)-1-((S)-7′-methyl-6′-(pyrimidin-2-yl)-3′,4′-dihydro-1′H-spiro[pyrrolidine-3,2-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 102) (5.6 mg, yield: 28%). LCMS (ESI): m/z 484 [M+1] ⁺ ; TLC: Rf 0.5 (dichloromethane:methanol=20:1). ^1H NMR (500MHz, MeOD) δ8.79(d,J＝4.8Hz,2H),7.75(d,J＝70.3Hz,1H),7.63(d,J＝1.7Hz,1H),7.29( dd,J＝6.4,3.2Hz,1H),7.08(d,J＝28.7Hz,1H),6.84(s,1H),6.72(d,J＝17.3Hz,1H),4.51(s,4H), 4.12–3.86(m,4H),3.76–3.35(m,4H),2.85(d,J＝6.3Hz,1H),2.59–2.49(m,3H),2.22–1.79(m,4H),1.47–1.39(m,3H).

Example 22: Preparation of 6-(1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'-H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)-1-oxopropane-2-yl)benzofuran-5-carbonitrile (Compound 77):

Step 22a: Preparation of 1-bromo-2-bromomethyl-4-methoxybenzene: Under nitrogen protection, a mixture of 1-bromo-4-methoxy-2-methylbenzene (2.5 g, 12.44 mmol, 1.0 eq.), N-bromosuccinimide (2.22 g, 12.44 mmol, 1.0 eq.) and azobisisobutyronitrile (409 mg, 2.49 mmol, 0.2 eq.) in 1,2-dichloroethane (25 ml) was stirred at 72°C overnight. Dichloromethane was added, and the mixture was washed with sodium thiosulfate solution and saturated brine. The organic phase was dried and concentrated under reduced pressure to obtain a yellow

Oily product 1-bromo-2-bromomethyl-4-methoxybenzene (4.08 g, crude product). LCMS (ESI): m/z=279 [M+1] ⁺ .

Step 22b: Preparation of 2-(2-bromo-5-methoxyphenyl)acetonitrile: Under nitrogen protection, a mixture of 1-bromo-2-bromomethyl-4-methoxybenzene (4.08 g, 12.44 mmol, 1.0 eq.), trimethylsilyl cyanide (1.85 g, 18.66 mmol, 1.5 eq.) and tetrabutylammonium fluoride (1M tetrahydrofuran solution, 18.7 ml, 18.66 mmol, 1.5 eq.) in acetonitrile (30 ml) was stirred at room temperature for 1 hour. The mixture was diluted with ethyl acetate, washed with water and saturated brine. The organic phase was dried and concentrated under reduced pressure to give a brown oily product, 2-(2-bromo-5-methoxyphenyl)acetonitrile (5.61 g, crude product). LCMS (ESI): m/z=226[M+1] ⁺ .

Step 22c: Preparation of 2-(2-bromo-5-methoxyphenyl)acetic acid: To a solution of 2-(2-bromo-5-methoxyphenyl)acetonitrile (5.61 g, 12.44 mmol, 1.0 eq) in ethanol (50 ml) was added an aqueous solution (50 ml) of potassium hydroxide (2.09 g, 37.32 mmol, 3.0 eq). The mixture was stirred at 85°C overnight. The mixture was concentrated to 75 ml and washed with ethyl acetate. The pH value of the aqueous phase was adjusted to 2 with concentrated hydrochloric acid. Ethyl acetate was added for extraction, and the mixture was washed with water and saturated brine. The organic phase was dried and concentrated under reduced pressure to give a yellow oily product, 2-(2-bromo-5-methoxyphenyl)acetic acid (1.86 g, yield: 60.7%). LCMS (ESI): m/z=245[M+1] ⁺ .

Step 22d: Preparation of methyl 2-(2-bromo-5-methoxyphenyl)acetate: Under nitrogen protection, oxalyl chloride (2M dichloromethane solution, 7.56 ml, 15.12 mmol, 2.0 eq.) was added dropwise to a mixture of 2-(2-bromo-5-methoxyphenyl)acetic acid (1.86 g, 7.56 mmol, 1.0 eq.) and N,N-dimethylformamide (0.1 ml) in 10 ml dichloromethane. The mixture was stirred at room temperature for 2 hours. 2 ml of methanol was added dropwise and the mixture was stirred for 30 minutes. The mixture was diluted with ethyl acetate and washed with water and saturated brine. The organic phase was dried and concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (eluent: petroleum ether/acetic acid Ethyl ester = 100/1 to 50/1) to give methyl 2-(2-bromo-5-methoxyphenyl)acetate (1.8 g, yield: 91.3%) as a yellow oil. MS (ES ⁺ ): m/z = 259 (M+H) ⁺ .

Step 22e: Preparation of methyl 2-(2-bromo-5-methoxyphenyl)propanoate: To a solution of methyl 2-(2-bromo-5-methoxyphenyl)acetate (437 mg, 1.68 mmol, 1.0 eq) in tetrahydrofuran was added dropwise, under nitrogen, lithium bis-(trimethylsilyl)amide (1M in tetrahydrofuran, 1.71 ml, 1.71 mmol, 1.02 eq) at -70°C. The mixture was stirred for 1.5 hours. A solution of iodomethane (429 mg, 3.02 mmol, 1.8 eq) in tetrahydrofuran was added dropwise and the mixture was stirred at -70°C for 1 hour. The mixture was then stirred at room temperature for 45 minutes. The reaction was quenched by adding ammonium chloride solution. Ethyl acetate was added for extraction and washed with water and saturated brine. The organic phase was dried and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 100/1 to 20/1) to give a colorless oily product, methyl 2-(2-bromo-5-methoxyphenyl)propanoate (350 mg, yield: 75.9%). LCMS (ESI): m/z = 273 [M+H] +.

Step 22f: Preparation of methyl 2-(2-cyano-5-methoxyphenyl)propanoate: A mixture of methyl 2-(2-bromo-5-methoxyphenyl)propanoate (719 mg, 2.63 mmol, 1.0 eq.) and cuprous cyanide (1.42 g, 15.80 mmol, 6.0 eq.) in 8 ml of N-methylpyrrolidone was stirred and heated in a microwave at 180°C for 2 hours. The mixture was filtered through celite. The filtrate was diluted with ethyl acetate, washed with water and saturated brine. The organic phase was dried and concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 100/1 to 10/1) to give methyl 2-(2-cyano-5-methoxyphenyl)propanoate (364 mg, yield: 63.1%) as a yellow oil. MS (ES ⁺ ): m/z = 220 (M+H) ⁺ .

Step 22g: Preparation of methyl 2-(2-cyano-4-iodo-5-methoxyphenyl)propionate: To a solution of methyl 2-(2-cyano-5-methoxyphenyl)propionate (331 mg, 1.51 mmol, 1.0 eq.) in trifluoroacetic acid (5 ml) was added N-iodosuccinimide (340 mg, 1.51 mmol, 1.0 eq.) at room temperature and stirred for 6 hours. The mixture was concentrated and sodium carbonate solution was added. Ethyl acetate was added for extraction and washed with water and saturated brine. The organic phase was dried and concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 80/1 to 5/1) to give a yellow oily product methyl 2-(2-cyano-4-iodo-5-methoxyphenyl)propionate (355 mg, yield: 68.0%). LCMS (ESI): m/z = 346 [M+1] ⁺ .

Step 22h: Preparation of 2-(2-cyano-5-hydroxy-4-iodophenyl)propionic acid: Under nitrogen protection, sodium hydride (145 mg, 3.63 mmol, 1.0 eq) was added to a solution of ethanethiol (225 mg, 3.63 mmol, 5.0 eq) in N,N-dimethylformamide (5 ml) at 0°C and stirred at room temperature for 30 minutes. A solution of methyl 2-(2-cyano-4-iodo-5-methoxyphenyl)propanoate (250 mg, 0.725 mmol, 1.0 eq) in N,N-dimethylformamide was added. The mixture was stirred at 155°C for 1 hour and diluted hydrochloric acid was added to quench the reaction. Ethyl acetate was added for extraction and washed with water and saturated brine. The organic phase was dried and concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 1/1 to 1/10) to obtain a yellow oily product 2-(2-cyano-5-hydroxy-4-iodophenyl)propanoic acid (173 mg, yield: 75.1%). LCMS (ESI): m/z = 318 [M+1] ⁺ .

Step 22i: Preparation of methyl 2-(2-cyano-5-hydroxy-4-iodophenyl)propanoate: Under nitrogen protection, 2-(2-cyano-5-hydroxy-4-iodophenyl)propanoic acid (160 mg, 0.505 mmol, 1.0 eq.) and N,N-dimethylformamide (0.05 ml) were added to 5% ethyl acetate. 1.52 mmol, 3.00 equiv.) was added dropwise to a mixture of 1.5 ml of dichloromethane and 2.0 ml of oxalyl chloride. The mixture was stirred at room temperature for 1.5 hours. 2 ml of methanol was added dropwise and the mixture was stirred for 15 minutes. The mixture was diluted with ethyl acetate and washed with water and saturated brine. The organic phase was dried and concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 2/1 to 1/5) to obtain a yellow oily substance 2-(2-cyano-5-hydroxy-4-iodophenyl) propionic acid methyl ester (145 mg, yield: 86.8%). MS (ES ⁺ ): m/z = 332 (M+H) ⁺ .

Step 22j: Preparation of methyl 2-(5-cyanobenzofuran-6-yl)propanoate: Under nitrogen, a mixture of methyl 2-(2-cyano-5-hydroxy-4-iodophenyl)propanoate (130 mg, 0.393 mmol, 1.0 eq), trimethylsilylacetylene (192 mg, 0.393 mmol, 1.0 eq), cuprous iodide (38 mg, 0.197 mmol, 0.5 eq), dichlorobistriphenylphosphine palladium (28 US shares, 0.04 mmol, 0.1 eq) and N,N-diisopropylethylamine (253 mg, 1.96 mmol, 5.0 eq) in 15 ml of tetrahydrofuran was stirred at 66° C. for 1.5 hours. The mixture was filtered through celite. The filtrate was concentrated to dryness under reduced pressure. The residue was dissolved in 10 ml of methanol, and then cuprous iodide (75 mg, 0.393 mmol, 1.0 eq.) and N,N-diisopropylethylamine (253 mg, 1.96 mmol, 2.5 eq.) were added. The mixture was stirred at 72°C for 2 hours. The mixture was diluted with dichloromethane, washed with ammonium chloride solution and saturated brine. The organic phase was dried and concentrated to dryness under reduced pressure. The residue was dissolved in 12 ml of tetrahydrofuran, and tetrabutylammonium fluoride (100 mg, 0.32 mmol, 0.8 eq.) was added. The mixture was diluted with ethyl acetate, washed with water and saturated brine. The organic phase was dried and concentrated to dryness under reduced pressure. The residue was subjected to thick preparative thin layer chromatography (developing solvent: petroleum ether/ethyl acetate = 20/1) to obtain a colorless oily substance 2-(5-cyanobenzofuran-6-yl)propionic acid methyl ester (46 mg, yield: 51.1%). MS (ES ⁺ ): m/z = 230 (M + H) ⁺ .

Step 22k: Preparation of 2-(5-cyanobenzofuran-6-yl)propanoic acid: To a solution of methyl 2-(5-cyanobenzofuran-6-yl)propanoate (46 mg, 0.2 mmol, 1.0 eq) in tetrahydrofuran/water (2 ml/0.5 ml) was added lithium hydroxide (17 mg, 0.4 mmol, 2.0 eq). The mixture was stirred at room temperature for 1 hour. The mixture was acidified with dilute hydrochloric acid. Ethyl acetate was added for extraction, and the mixture was washed with water and saturated brine. The organic phase was dried and concentrated under reduced pressure to give a yellow solid product, 2-(5-cyanobenzofuran-6-yl)propanoic acid (30 mg, yield: 69.7%). LCMS (ESI): m/z=216[M+1] ⁺ .

Step 221: Preparation of 6-(1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'-H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)-1-oxopropan-2-yl)benzofuran-5-carbonitrile (Compound 77): (S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (0122- A mixture of dichloromethane (2 ml) of 1-(4-nitrobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (42 mg, 0.11 mmol, 1.1 eq.) and 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (35 mg, 0.09 mmol, 0.9 eq.) was stirred at room temperature for 30 minutes. The mixture was diluted with dichloromethane and washed with water and saturated brine. The organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was purified by thick preparative thin layer chromatography (developing solvent: dichloromethane/methanol = 20/1) to give a yellow solid product 6-(1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'-H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)-1-oxopropane-2-yl)benzofuran-5-carbonitrile (38 mg, yield: 88.3%). LCMS (ESI): m/z=465[M+H] ⁺ . ^1H NMR(500MHz,MeOD)δ8.81(dt,J＝8.6,4.4Hz,2H),8.15–7.62(m,4H),7.33–7.12(m,1H),6.93(dd,J＝37.9,1.3Hz,1H) ,4.57–4.30(m,1H),4.04–3.42(m,4H),2.92–2.61(m,2H),2.63–2.42(m,3H),2.20–1.69(m,4H),1.64–1.49(m,3H).

Example 23: Preparation of (2R)-1-(5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'-H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)-2-(5-fluoro-2-methoxypyridin-4-yl)propan-1-one (Compound 55) (Prepared according to Schemes 1 and 4)

Step 23a: Preparation of 1-(tert-butyl)2-methyl-4-hydroxy-4-(trimethylsilyl)ethynyl)pyrrolidine-1,2-dicarboxylate (Compound 0102-55): To a mixture of ethynyltrimethylsilane (4.85 g, 49.33 mmol, 1.2 eq) in tetrahydrofuran (60 mL) was added dropwise n-butyllithium (2.5 M in hexane, 17.3 mL, 43.16 mmol, 1.05 eq) at -78°C. The mixture was stirred at -78°C under nitrogen for 1 hour. A solution of tert-butyl 2-acetoxy-4-oxopyrrolidine-1-carboxylate (0101-55) (10.0 g, 41.11 mmol, 1.0 eq) in tetrahydrofuran (40 mL) was added dropwise. The mixture was warmed to room temperature and stirred overnight. Saturated ammonium chloride solution (60 ml) was added to quench the reaction. The aqueous layer was extracted with ethyl acetate (50 ml x 3). The combined organic layer was washed with saturated brine (50 ml), dried over anhydrous sodium sulfate and concentrated to give a brown oily substance 1-(tert-butyl) 2-methyl 4-hydroxy-4-(trimethylsilyl)ethynyl)pyrrolidine-1,2-dicarboxylate (12.2 g, yield: 87%). LCMS (ESI): m/z 342 [M+1] ⁺ ; TLC: Rf 0.5 (dichloromethane:methanol=60:1).

Step 23b: Preparation of 1-(tert-butyl)-2-methyl-4-ethynyl-4-hydroxypyrrolidine-1,2-dicarboxylate (Compound 0103-55): To a mixture of 1-(tert-butyl)-2-methyl-4-hydroxy-4-(trimethylsilyl)ethynyl)pyrrolidine-1,2-dicarboxylate (0102-55) (12.2 g, 35.78 mmol, 1.0 eq) in methanol (50 mL) was added potassium carbonate (7.4 g, 53.67 mmol, 1.5 eq). The mixture was stirred at room temperature for 3 hours. The solvent was removed under reduced pressure. The residue was diluted with water (60 mL) and then extracted with ethyl acetate (50 mL x 3). The combined organic layers were washed with saturated brine (50 mL), dried over anhydrous sodium sulfate and concentrated to give 1-(tert-butyl) 2-methyl 4-ethynyl-4-hydroxypyrrolidine-1,2-dicarboxylate (5.61 g, yield: 58%) as a brown oil. LCMS (ESI): m/z 270 [M+1] ⁺ ; TLC: Rf 0.4 (petroleum ether:ethyl acetate=3:1).

Step 23c: Preparation of 1-(tert-butyl) 2-methyl 4-acetoxy-4-ethynylpyrrolidine-1,2-dicarboxylate (Compound 0104-55): To a mixture of 1-(tert-butyl) 2-methyl 4-ethynyl-4-hydroxypyrrolidine-1,2-dicarboxylate (0103-55) (5.61 g, 20.86 mmol, 1.0 eq) and N,N-diisopropylethylamine (9.2 mL, 52.14 mmol, 2.5 eq) in dichloromethane (50 mL) was added acetyl chloride (2.68 mL, 35.46 mmol, 1.7 eq) dropwise at 0°C. The mixture was warmed to room temperature and stirred for 1 hour. The mixture was diluted with water (50 mL) and then extracted with dichloromethane (30 mL x 3). The combined organic layers were washed with saturated brine (30 mL), dried over anhydrous sodium sulfate and concentrated. The residue was separated by column chromatography on silica gel (petroleum ether: ethyl acetate 5: 1) to give 1-(tert-butyl) 2-methyl 4-acetoxy-4-ethynylpyrrolidine-1,2-dicarboxylate (4.92 g, yield: 76%) as a light yellow oil. LCMS (ESI): m/z 312 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 3: 1).

Step 23d: 1-(tert-butyl)2-methyl-4-ethynyl-4-((4-methoxybenzyl)amino)pyrrolidine-1,2-dicarboxylate (compound Preparation of compound 0105-55): To a mixture of p-methoxybenzylamine (4.16 g, 30.35 mmol, 2.0 eq.) and cuprous chloride (0.15 g, 1.52 mmol, 0.1 eq.) in tetrahydrofuran (50 ml) was added dropwise a solution of 1-(tert-butyl) 2-methyl 4-acetoxy-4-ethynylpyrrolidine-1,2-dicarboxylate (0104-55) (4.72 g, 15.18 mmol, 1.0 eq.) in tetrahydrofuran (30 ml) at 70°C. The mixture was stirred under a nitrogen atmosphere at 70°C for 1.5 hours. The mixture was diluted with water (50 ml) and then extracted with ethyl acetate (30 ml x 3). The combined organic layer was washed with saturated brine (30 ml), dried over anhydrous sodium sulfate and concentrated. The residue was separated by column chromatography on silica gel (petroleum ether: ethyl acetate 8: 1) to give 1-(tert-butyl) 2-methyl 4-ethynyl-4-((4-methoxybenzyl) amino) pyrrolidine-1,2-dicarboxylate (2.06 g, yield: 35%) as a pale yellow oil. LCMS (ESI): m/z 389 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 4: 1).

Step 23e: Preparation of 1-(tert-butyl)2-methyl 4-((2-chloro-6-methylpyridin-3-yl)ethynyl)-4-((4-methoxybenzyl)amino)pyrrolidine-1,2-dicarboxylate (Compound 0108-55): 2-chloro-3-iodo-6-methylpyridine (0107-1) (1.41 g, 5.57 mmol, 1.05 equiv), bistriphenylphosphine palladium dichloride (0 1-(tert-butyl)-2-methyl-4-ethynyl-4-((4-methoxybenzyl)amino)pyrrolidine-1,2-dicarboxylate (0105-55) (2.06 g, 5.31 mmol, 1.0 eq.) was added to a mixture of triethylamine (25 ml) with 1-(tert-butyl)-2-methyl-4-ethynyl-4-((4-methoxybenzyl)amino)pyrrolidine-1,2-dicarboxylate (0105-55) (2.06 g, 5.31 mmol, 1.0 eq.) and cuprous iodide (51 mg, 0.266 mmol, 0.05 eq.). The mixture was heated to 80°C under a nitrogen atmosphere for 3.5 hours. The solvent was removed under reduced pressure. The residue was diluted with water (50 ml) and then extracted with ethyl acetate (30 ml x 3). The combined organic layer was washed with saturated brine (30 ml), dried over anhydrous sodium sulfate and concentrated. The residue was subjected to column chromatography on silica gel (petroleum ether:ethyl acetate 6:1 to 2:1) to give a pale yellow oily substance 1-(tert-butyl)2-methyl 4-((2-chloro-6-methylpyridin-3-yl)ethynyl)-4-((4-methoxybenzyl)amino)pyrrolidine-1,2-dicarboxylate (2.10 g, yield: 77%). LCMS (ESI): m/z 514 [M+1] ⁺ ; TLC: Rf 0.4 (petroleum ether:ethyl acetate=3:1).

Step 23f: Preparation of 1-(tert-butyl)2-methyl 4-(2-(2-chloro-6-methylpyridin-3-yl)ethyl)-4-((4-methoxybenzyl)amino)pyrrolidine-1,2-dicarboxylate (Compound 0109-55): To a mixture of 1-(tert-butyl)2-methyl 4-((2-chloro-6-methylpyridin-3-yl)ethynyl)-4-((4-methoxybenzyl)amino)pyrrolidine-1,2-dicarboxylate (0108-55) (2.1 g, 4.09 mmol, 1.0 eq) in methanol (20 ml) was added platinum dioxide (0.186 g, 0.82 mmol, 0.2 eq). The mixture was stirred at room temperature under hydrogen balloon pressure for 40 hours. The mixture was filtered. The filtrate was concentrated under reduced pressure to give 1-(tert-butyl)2-methyl 4-(2-(2-chloro-6-methylpyridin-3-yl)ethyl)-4-((4-methoxybenzyl)amino)pyrrolidine-1,2-dicarboxylate (2.14 g, crude product) as a pale yellow oil. LCMS (ESI): m/z 518 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether:ethyl acetate=2:1).

Step 23g: Preparation of tert-butyl 1'-(4-methoxybenzyl)-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (Compound 0110-55):

To a mixture of 1-(tert-butyl)2-methyl 4-(2-(2-chloro-6-methylpyridin-3-yl)ethyl)-4-((4-methoxybenzyl)amino)pyrrolidine-1,2-dicarboxylate (0109-55) (2.14 g, 4.14 mmol, 1.0 eq), palladium acetate (46 mg, 0.21 mmol, 0.05 eq) and 2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl (191 mg, 0.41 mmol, 0.1 eq) in N-methylpyrrolidone (20 ml) was added sodium tert-butoxide (0.795 g, 8.28 mmol, 2.0 eq). The mixture was heated to 100°C in a microwave reactor for 1 hour. The mixture was diluted with water (40 ml). 2M sodium hydroxide solution was added to adjust pH=12, and then the mixture was washed with methyl tert-butyl ether (15 ml×2). 1M dilute hydrochloric acid solution was added to the aqueous layer to adjust pH=7, and then extracted with ethyl acetate (20 ml×4). The combined organic layer was washed with saturated brine (30 ml), dried over anhydrous sodium sulfate and concentrated to give a brown oily substance 1-(tert-butyloxycarbonyl)-1'-(4-methoxybenzyl)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-5-carboxylic acid (2.13 g, crude product). LCMS (ESI): m/z 468[M+1] ⁺ ; TLC: Rf 0.5 (dichloromethane:methanol=10:1).

Borane dimethyl sulfide complex (10 M dimethyl sulfide solution, 0.87 ml, 8.73 mmol, 2.5 eq) was added to a mixture of 1-(tert-butyloxycarbonyl)-1'-(4-methoxybenzyl)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-5-carboxylic acid (1.63 g, 3.49 mmol, 1.0 eq) in tetrahydrofuran (20 ml). The mixture was heated to 65°C under a nitrogen atmosphere for 1.5 hours. Water (50 ml) was added to quench the reaction. The aqueous layer was extracted with ethyl acetate (20 ml x 3). The combined organic layers were washed with saturated brine (20 mL), dried over anhydrous sodium sulfate and concentrated to give a pale yellow oily substance, tert-butyl 5-(hydroxymethyl)-1'-(4-methoxybenzyl)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (1.39 g, yield: 88%). LCMS (ESI): m/z 454 [M+1] ⁺ ; TLC: Rf 0.5 (dichloromethane:methanol=20:1).

To a mixture of tert-butyl 5-(hydroxymethyl)-1'-(4-methoxybenzyl)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (0.79 g, 1.74 mmol, 1.0 eq) and N,N-diisopropylethylamine (449 mg, 3.48 mmol, 2.0 eq) in dichloromethane (10 ml) was added methanesulfonyl chloride (0.2 ml, 2.62 mmol, 1.5 eq) dropwise at 0°C. The mixture was warmed to room temperature and stirred for 22 hours. The mixture was diluted with water (30 ml) and then extracted with ethyl acetate (30 ml x 3). The combined organic layer was washed with saturated brine (30 ml), dried over anhydrous sodium sulfate and concentrated. The residue was separated by column chromatography on silica gel (petroleum ether: ethyl acetate 3: 1) to give a pale yellow oily substance, tert-butyl 1'-(4-methoxybenzyl)-7'-methyl-5-(((methylsulfonyl)oxy)methyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (0.545 g, yield: 59%). LCMS (ESI): m/z 532 [M+1] ⁺ ; TLC: Rf 0.5 (dichloromethane:methanol=20:1).

To a mixture of tert-butyl 1'-(4-methoxybenzyl)-7'-methyl-5-(((methylsulfonyl)oxy)methyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (0.545 g, 1.03 mmol, 1.0 equiv) in tetrahydrofuran (6 mL) at 0°C was added lithium triethylborohydride (1 M in tetrahydrofuran, 3.09 mL, 3.09 mmol, 3.0 equiv) dropwise. The mixture was warmed to room temperature and then stirred for 6 hours. Water (30 ml) was added to quench the reaction. The aqueous layer was extracted with ethyl acetate (15 ml×3). The combined organic layer was washed with saturated brine (20 ml), dried over anhydrous sodium sulfate and concentrated to give a light yellow oily substance 1'-(4-methoxybenzyl)-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (480 mg, crude product). LCMS (ESI): m/z 438[M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether:ethyl acetate=5:1).

Step 23h: Preparation of tert-butyl 5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (Compound 0112-55): To a mixture of tert-butyl 1'-(4-methoxybenzyl)-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (0110-55) (450 mg, 1.03 mmol, 1.0 equiv) in dichloromethane (6 mL) was added trifluoroacetic acid (1.5 mL). The mixture was stirred at room temperature for 2 hours. The solvent was removed under reduced pressure. The residue was dissolved in water (10 mL) and tetrahydrofuran (10 mL). Solid sodium carbonate was added to adjust the pH to 9. Di-tert-butyl dicarbonate (449 mg, 2.06 mmol, 2.0 eq) was added, and the mixture was stirred at room temperature for 1 hour. The mixture was diluted with water (20 mL), and then extracted with ethyl acetate (15 mL×3). The combined organic layer was washed with saturated brine (20 mL), dried over anhydrous sodium sulfate and concentrated. The residue was subjected to column chromatography on silica gel (petroleum ether: ethyl acetate 3:1) to give a pale yellow oily substance tert-butyl 5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (193 mg, yield: 59%). LCMS (ESI): m/z 318 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 1:1).

Step 23i: Preparation of tert-butyl 6'-bromo-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (Compound 0115-55): To a mixture of tert-butyl 5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (0112-55) (193 mg, 0.61 mmol, 1.0 equiv) in dichloromethane (5 mL) was added dibromohydantoin (96 mg, 0.34 mmol, 0.55 equiv) at 0°C. The mixture was stirred at 0°C for 20 minutes. Saturated aqueous sodium sulfite solution (20 mL) was added to quench the reaction. The aqueous layer was extracted with ethyl acetate (15 mL x 3). The combined organic layers were washed with saturated brine (20 mL), dried over anhydrous sodium sulfate and concentrated to give tert-butyl 6'-bromo-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (255 mg, crude) as a pale yellow oil. LCMS (ESI): m/z 396 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether:ethyl acetate=3:1).

Step 23j: Preparation of (1-(tert-Butyloxycarbonyl)-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-6'-yl)boronic acid (Compound 0117-55): tert-butyl 6'-bromo-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (0115-55) (242 mg, 0.61 mmol, 1.0 equiv), Xphos-Pd-G 2 (9.6 mg, 0.012 mmol, 0.02 eq), 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (8.7 mg, 0.018 mmol, 0.03 eq), potassium acetate (424 mg, 4.32 mmol, 2.5 eq) and sodium tert-butoxide (4.2 mg, 0.043 mmol, 0.025 eq) were added to a mixture of methanol (6 ml) and ethylene glycol (0.6 ml). Tetrahydroxydiboron (137 mg, 1.532 mmol, 2.5 eq) was added. The mixture was heated to 55° C. under nitrogen atmosphere for 1.5 hours. The solvent was removed under reduced pressure. The residue was diluted with water (20 ml). 2M sodium hydroxide solution was added to adjust pH=12, and then the mixture was washed with methyl tert-butyl ether (10 ml×2). 2M dilute hydrochloric acid solution was added to the aqueous layer to adjust the pH to 8, and then extracted with ethyl acetate (15 ml x 3). The combined organic layers were washed with saturated brine. (15 ml), dried over anhydrous sodium sulfate and concentrated to give a colorless oily substance (1-(tert-butyloxycarbonyl)-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridin]-6'-yl)boronic acid (165 mg, yield: 75%). LCMS (ESI): m/z 362 [M+1] ⁺ ; TLC: Rf 0.3 (dichloromethane:methanol=10:1).

Step 23k: Preparation of tert-butyl 5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (Compound 0119-55): To (1-(tert-butyloxycarbonyl)-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-6'-yl)boronic acid (0117-55) (165 mg, 0.457 mmol, 1.0 equiv.), Xphos-Pd-G2 (10.8 mg, 0.014 mmol, 0.03 equiv.), 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (6.7 mg, 0.014 mmol, 0.03 equiv.) and sodium carbonate (145 mg, 1.37 mmol, 3.0 equiv.) were added to a mixture of toluene (2.5 ml), ethanol (2.5 ml) and water (1 ml). The mixture was heated to 55°C for 4 hours under a nitrogen atmosphere. The mixture was diluted with water (20 ml) and then extracted with ethyl acetate (15 ml x 3). The combined organic layer was washed with saturated brine (10 ml), dried over anhydrous sodium sulfate and concentrated. The residue was purified by preparative thin layer chromatography (ethyl acetate:petroleum ether=5:1) to give a pale yellow solid tert-butyl 5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (109 mg, yield: 60%). LCMS (ESI): m/z 396 [M+1] ⁺ ; TLC: Rf 0.5 (ethyl acetate:petroleum ether=5:1).

Step 231: Preparation of 5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (Compound 0121-55): A mixture of tert-butyl 5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (0119-55) (109 mg, 0.276 mmol, 1.0 eq) in hydrogen chloride/methanol solution (4M solution, 2 ml) was stirred at room temperature for 3 hours. The solvent was removed under reduced pressure. The residue was dried under vacuum to give a pale yellow solid 5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (105 mg, crude product). LCMS (ESI): m/z 296 [M+1] ⁺ ; TLC: Rf 0.3 (dichloromethane:methanol=10:1).

Step 23m: Preparation of (2R)-1-(5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'-H-spiro[pyrrolidin-3,2'-[1,8]naphthyridine]-1-yl)-2-(5-fluoro-2-methoxypyridin-4-yl)propan-1-one (Compound 55): to (R)-2-(5-fluoro-2-methoxypyridin-4-yl)propanoic acid (0406-7) (27.5 mg, 0.138 mmol, 1.0 equiv), benzotriazole-N,N,N',N'-tetramethyluronium hexafluoro Phosphate (63 mg, 0.166 mmol, 1.2 eq), 1-hydroxybenzotriazole (20 mg, 0.152 mmol, 1.1 eq) and N,N-diisopropylethylamine (89 mg, 0.69 mmol, 5.0 eq) in dichloromethane (3 ml) was added 5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (0121-55) (51 mg, 0.138 mmol, 1.0 eq). The mixture was stirred at room temperature overnight. The mixture was diluted with water (20 ml) and then extracted with ethyl acetate (10 ml x 3). The combined organic layer was washed with saturated brine (15 ml), dried over anhydrous sodium sulfate and concentrated. The residue was purified by preparative thin layer chromatography (dichloromethane:methanol:aqueous ammonia=80:3:0.8) to give a white solid (2R)-1-(5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'-H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)-2-(5-fluoro-2-methoxypyridin-4-yl)propan-1-one (51 mg, yield: 78%). LCMS (ESI): m/z 477 [M+1] ⁺ ; TLC: Rf 0.5 (dichloromethane: Methanol=20:1). ^1H NMR(500MHz,MeOD)δ8.82(dt,J＝9.0,5.0Hz,2H),7.88(ddd,J＝127.8,64.9,35.9Hz,2H),7.34–7.24(m,1H),6.93–6.66(m,1H),4.43–4.06(m,2H), 3.87(dd,J＝19.4,11.6Hz,3H),3.75–3.45(m,2H),2.93–2.68(m,2H),2.6 3–2.53(m,3H),2.38–2.13(m,1H),2.01–1.61(m,3H),1.45–1.31(m,6H).

Example 24: Preparation of (R)-1-((3R,5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'-H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)-2-(5-fluoro-2-methoxypyridin-4-yl)propan-1-one (Compound 100) (Prepared according to Schemes 4 and 5)

Step 24a: Preparation of (3S,5S)-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (0113-100):

To a mixture of ethynyltrimethylsilane (7.27 g, 73.99 mmol, 1.2 eq) in tetrahydrofuran (70 ml) was added n-butyllithium (2.5 M in hexane, 25.90 ml, 64.74 mmol, 1.05 eq) dropwise at -78°C. The mixture was stirred at -78°C under a nitrogen atmosphere for 1 hour. A solution of (S)-tert-butyl 2-acetoxy-4-oxopyrrolidine-1-carboxylate (15.0 g, 61.66 mmol, 1.0 eq) in tetrahydrofuran (50 ml) was added dropwise. The mixture was warmed to room temperature and then stirred overnight. Saturated ammonium chloride solution (50 ml) was added to quench the reaction. The aqueous layer was extracted with ethyl acetate (50 ml x 3). The combined organic layers were washed with saturated brine (50 mL), dried over anhydrous sodium sulfate and concentrated to give a brown solid 1-(tert-butyl) 2-methyl (2R)-4-hydroxy-4-((trimethylsilyl)ethynyl)pyrrolidine-1,2-dicarboxylate (17.5 g, yield: 83%). LCMS (ESI): m/z 342 [M+1] ⁺ ; TLC: Rf 0.5 (dichloromethane:methanol=60:1).

Potassium carbonate (10.6 g, 76.98 mmol, 1.5 eq.) was added to a mixture of 1-(tert-butyl)2-methyl(2R)-4-hydroxy-4-((trimethylsilyl)ethynyl)pyrrolidine-1,2-dicarboxylate (17.5 g, 51.32 mmol, 1.0 eq.) in methanol (45 ml). The mixture was stirred at room temperature for 1 hour. The solvent was removed under reduced pressure. The residue was diluted with water (80 ml) and then extracted with ethyl acetate (50 ml×4). The combined organic layer was washed with saturated brine (50 ml), dried over anhydrous sodium sulfate and concentrated to give 1-(tert-butyl)2-methyl(2R)-4-ethynyl-4-hydroxypyrrolidine-1,2-dicarboxylate (9.74 g, yield: 71%) as a brown oil. LCMS (ESI): m/z 270 [M+1] ⁺ ; TLC: Rf 0.4 (petroleum ether:ethyl acetate=3:1).

At 0°C, 1-(tert-butyl) 2-methyl (2R)-4-ethynyl-4-hydroxypyrrolidine-1,2-dicarboxylate (9.74 g, 36.21 To a mixture of 1,4-diisopropylethylamine (11.68 g, 90.52 mmol, 2.5 eq.) and diisopropylethylamine (11.68 g, 90.52 mmol, 2.5 eq.) in dichloromethane (100 ml) was added acetyl chloride (4.65 ml, 61.56 mmol, 1.7 eq.) dropwise. The mixture was warmed to room temperature and then stirred for 1.5 hours. The mixture was diluted with water (60 ml) and then extracted with dichloromethane (30 ml x 3). The combined organic layer was washed with saturated brine (30 ml), dried over anhydrous sodium sulfate and concentrated. The residue was subjected to column chromatography on silica gel (petroleum ether: ethyl acetate 4:1) to give 1-(tert-butyl) 2-methyl (2R)-4-acetoxy-4-ethynylpyrrolidine-1,2-dicarboxylate (9.50 g, yield: 84%) as a pale yellow oil. LCMS (ESI): m/z 312 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether:ethyl acetate=3:1).

To a mixture of p-methoxybenzylamine (20.29 g, 147.9 mmol, 2.0 eq.) and cuprous chloride (0.732 g, 7.40 mmol, 0.1 eq.) in tetrahydrofuran (250 ml) was added dropwise a solution of 1-(tert-butyl) 2-methyl (2R)-4-acetoxy-4-ethynylpyrrolidine-1,2-dicarboxylate (23 g, 73.95 mmol, 1.0 eq.) in tetrahydrofuran (100 ml) at 70°C. The mixture was stirred under a nitrogen atmosphere at 70°C for 1.5 hours. The mixture was diluted with water (150 ml) and then extracted with ethyl acetate (100 ml x 2). The combined organic layer was washed with saturated brine (100 ml), dried over anhydrous sodium sulfate and concentrated. The residue was separated by column chromatography on silica gel (petroleum ether: ethyl acetate 8: 1) to give 1-(tert-butyl) 2-methyl (2R)-4-ethynyl-4-((4-methoxybenzyl)amino)pyrrolidine-1,2-dicarboxylate (9.26 g, yield: 32%) as a light yellow oil. LCMS (ESI): m/z 389 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 4: 1).

To a mixture of 2-chloro-3-iodo-6-methylpyridine (0107-1) (6.33 g, 25.06 mmol, 1.05 eq.), bistriphenylphosphine palladium dichloride (0.838 g, 1.19 mmol, 0.05 eq.) and cuprous iodide (0.227 g, 1.19 mmol, 0.05 eq.) in triethylamine (100 ml) was added 1-(tert-butyl) 2-methyl (2R)-4-ethynyl-4-((4-methoxybenzyl)amino) pyrrolidine-1,2-dicarboxylate (9.26 g, 23.87 mmol, 1.0 eq.). The mixture was heated to 80°C under nitrogen atmosphere for 8 hours. The solvent was removed under reduced pressure. The residue was diluted with water (50 ml) and then extracted with ethyl acetate (50 ml x 3). The combined organic layer was washed with saturated brine (50 ml), dried over anhydrous sodium sulfate and concentrated. The residue was separated by column chromatography on silica gel (petroleum ether: ethyl acetate 6:1 to 3:1) to obtain a light yellow oily substance 1-(tert-butyl) 2-methyl (2R)-4-((2-chloro-6-methylpyridin-3-yl)ethynyl)-4-(4-methoxybenzyl)amino)pyrrolidine-1,2-dicarboxylate (10.02 g, yield: 82%). LCMS (ESI): m/z 514 [M+1] ⁺ ; TLC: Rf 0.4 (petroleum ether: ethyl acetate = 3:1).

Platinum dioxide (0.887 g, 39.06 mmol, 0.2 eq.) was added to a mixture of 1-(tert-butyl)2-methyl (2R)-4-((2-chloro-6-methylpyridin-3-yl)ethynyl)-4-(4-methoxybenzyl)amino)pyrrolidine-1,2-dicarboxylate (10.02 g, 19.53 mmol, 1.0 eq.) in methanol (80 ml). The mixture was stirred at room temperature for 40 hours under hydrogen balloon pressure. The mixture was filtered. The filtrate was concentrated under reduced pressure to give 1-(tert-butyl)2-methyl (2R)-4-(2-(2-chloro-6-methylpyridin-3-yl)ethyl)-4-((4-methoxybenzyl)amino)pyrrolidine-1,2-dicarboxylate (9.56 g, crude) as a pale yellow oil. LCMS (ESI): m/z 518 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether:ethyl acetate=2:1).

At 0°C, 1-(tert-butyl)2-methyl(2R)-4-(2-(2-chloro-6-methylpyridin-3-yl)ethyl)-4-((4-methoxybenzyl) To a mixture of (2R)-4-(2-(2-chloro-6-methylpyridin-3-yl)ethyl)-2-(hydroxymethyl)-4-((4-methoxybenzyl)amino)pyrrolidine-1,2-dicarboxylate (9.0 g, 17.41 mmol, 1.0 eq.) in tetrahydrofuran (60 ml) was slowly added lithium aluminum tetrahydride (2.65 g, 69.63 mmol, 4.0 eq.). The mixture was warmed to room temperature and stirred for 3 hours. The mixture was cooled to 0°C. Water (10.5 ml) and 15% sodium hydroxide solution (2.65 ml) were added. The mixture was warmed to room temperature and stirred for 10 minutes. The mixture was diluted with ethyl acetate (50 ml) and then filtered. The filtrate was washed with saturated brine (50 ml), dried over anhydrous sodium sulfate and concentrated to give a light yellow oily substance (2R)-4-(2-(2-chloro-6-methylpyridin-3-yl)ethyl)-2-(hydroxymethyl)-4-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylic acid tert-butyl ester (8.05 g, yield: 95%). LCMS (ESI): m/z 490 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether:ethyl acetate=2:1).

To a mixture of tert-butyl (2R)-4-(2-(2-chloro-6-methylpyridin-3-yl)ethyl)-2-(hydroxymethyl)-4-((4-methoxybenzyl)amino)pyrrolidine-1-carboxylate (8.05 g, 16.46 mmol, 1.0 eq), palladium acetate (0.184 g, 0.82 mmol, 0.05 eq) and 2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl (0.77 g, 1.65 mmol, 0.1 eq) in N-methylpyrrolidone (50 ml) was added sodium tert-butoxide (3.16 g, 32.92 mmol, 2.0 eq). The mixture was heated to 100° C. in a microwave reactor for 1 hour. The mixture was diluted with water (20 ml) and tetrahydrofuran (20 ml). Di-tert-butyl dicarbonate (4.67 g, 21.40 mmol, 1.3 eq) was added, and the mixture was stirred at room temperature for 1 hour. The mixture was diluted with water (60 ml), and then extracted with ethyl acetate (40 ml×3). The combined organic layer was washed with saturated brine (50 ml), dried over anhydrous sodium sulfate and concentrated. The residue was subjected to column chromatography on silica gel (petroleum ether: ethyl acetate 8:1 to 3:1) to give a pale yellow oily substance (3S, 5R)-5-(hydroxymethyl)-1'-(4-methoxybenzyl)-7'-methyl-3', 4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (833 mg, yield: 11%). LCMS (ESI): m/z 454 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 2:1).

To a mixture of (3S,5R)-5-(hydroxymethyl)-1'-(4-methoxybenzyl)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (833 mg, 1.84 mmol, 1.0 eq) and N,N-diisopropylethylamine (475 mg, 3.68 mmol, 2.0 eq) in dichloromethane (10 ml) was added methanesulfonyl chloride (0.21 ml, 2.76 mmol, 1.5 eq) dropwise at 0°C. The mixture was warmed to room temperature and stirred for 6 hours. The mixture was diluted with water (30 ml) and then extracted with ethyl acetate (15 ml x 4). The combined organic layer was washed with saturated brine (20 ml), dried over anhydrous sodium sulfate and concentrated. The residue was separated by column chromatography on silica gel (petroleum ether: ethyl acetate 3: 1) to give a pale yellow oily substance (3S, 5R)-1'-(4-methoxybenzyl)-7'-methyl-5-(((methylsulfonyl)oxy)methyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (0.92 g, yield: 94%). LCMS (ESI): m/z 532 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 2: 1).

To a mixture of tert-butyl (3S,5R)-1'-(4-methoxybenzyl)-7'-methyl-5-(((methylsulfonyl)oxy)methyl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (0.92 g, 1.73 mmol, 1.0 eq) in tetrahydrofuran (10 mL) was added dropwise lithium triethylborohydride (1 M in tetrahydrofuran, 6.93 mL, 6.93 mmol, 4.0 eq) at 0°C. The mixture was warmed to room temperature and then stirred overnight. Water (30 mL) was added to quench the reaction. The aqueous layer was washed with ethyl acetate (15 mL) ×3). The combined organic layer was washed with saturated brine (20 ml), dried over anhydrous sodium sulfate and concentrated to give a light yellow oily substance (3S,5S)-1'-(4-methoxybenzyl)-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (800 mg, crude product). LCMS (ESI): m/z 438 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether:ethyl acetate=5:1).

To a mixture of (3S,5S)-1'-(4-methoxybenzyl)-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (756 mg, 1.73 mmol, 1.0 eq) in dichloromethane (12 ml) was added trifluoroacetic acid (3 ml). The mixture was stirred at room temperature for 2 hours. The solvent was removed under reduced pressure. The residue was dissolved in water (10 ml) and tetrahydrofuran (10 ml). Solid sodium carbonate was added to adjust pH=9. Di-tert-butyl dicarbonate (566 mg, 2.60 mmol, 1.5 eq) was added, and the mixture was stirred at room temperature for 1 hour. The mixture was diluted with water (20 ml), and then extracted with ethyl acetate (15 ml×3). The combined organic layer was washed with saturated brine (20 ml), dried over anhydrous sodium sulfate and concentrated. The residue was separated by column chromatography on silica gel (petroleum ether: ethyl acetate 3:1) to give a pale yellow oily substance (3S,5S)-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (548 mg, yield: 100%). LCMS (ESI): m/z 318 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether: ethyl acetate = 1:1).

Step 24b: Preparation of (3S,5S)-6'-bromo-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (Compound 0116-100): To a mixture of (3S,5S)-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (0113-100) (548 mg, 1.73 mmol, 1.0 equiv) in dichloromethane (10 mL) at 0° C. was added dibromohydantoin (272 mg, 0.95 mmol, 0.55 equiv). The mixture was stirred at 0° C. for 0.5 h. The reaction was quenched by the addition of saturated aqueous sodium sulfite (15 mL). The aqueous layer was extracted with ethyl acetate (15 ml x 3). The combined organic layers were washed with saturated brine (20 ml), dried over anhydrous sodium sulfate and concentrated to give a pale yellow oily substance (3S,5S)-6'-bromo-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (754 mg, crude product). LCMS (ESI): m/z 396 [M+1] ⁺ ; TLC: Rf 0.5 (petroleum ether:ethyl acetate=3:1).

Step 24c: Preparation of ((3S,5S)-1-(tert-butyloxycarbonyl)-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-6'-yl)boronic acid (Compound 0118-100): to (3S,5S)-6'-bromo-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (0116-100) (685 mg, 1.73 mmol, 1.0 equiv) , Xphos-Pd-G2 (27 mg, 0.035 mmol, 0.02 eq), 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (25 mg, 0.052 mmol, 0.03 eq), potassium acetate (424 mg, 4.32 mmol, 2.5 eq) and sodium tert-butoxide (4.2 mg, 0.043 mmol, 0.025 eq) were added to a mixture of methanol (10 ml) and ethylene glycol (1 ml). Tetrahydroxydiboron (388 mg, 4.32 mmol, 2.5 eq) was added. The mixture was heated to 55°C under a nitrogen atmosphere for 2 hours. The solvent was removed under reduced pressure. The residue was diluted with water (30 ml). 2M sodium hydroxide solution was added to adjust pH = 12, and then the mixture was washed with methyl tert-butyl ether (10 ml × 2). 2M dilute hydrochloric acid solution was added to the aqueous layer to adjust pH=8, and then extracted with ethyl acetate (15 ml×3). The combined organic layer was washed with saturated brine (15 ml), dried over anhydrous sodium sulfate and concentrated to obtain a white solid ((3S,5S)-1-(tert-butyloxycarbonyl)-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-6'-yl)boronic acid (299 mg, yield: 48%). LCMS (ESI): m/z 362 [M+1] ⁺ ; TLC: Rf 0.3 (dichloromethane:methanol=10:1).

Step 24d: Preparation of (3S,5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (Compound 0120-100): To ((3S,5S)-1-(tert-butyloxycarbonyl)-5,7'-dimethyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-6'-yl)boronic acid (0118-100) (299 mg, 0. 828 mmol, 1.0 eq.), Xphos-Pd-G2 (19.5 mg, 0.025 mmol, 0.03 eq.), 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (11.9 mg, 0.025 mmol, 0.03 eq.) and sodium carbonate (263 mg, 2.48 mmol, 3.0 eq.) were added to a mixture of toluene (5 ml), ethanol (5 ml) and water (2 ml). The mixture was heated to 55°C for 5 hours under a nitrogen atmosphere. The solvent was removed under reduced pressure. The residue was diluted with water (20 ml) and then extracted with ethyl acetate (15 ml x 3). The combined organic layer was washed with saturated brine (15 ml), dried over anhydrous sodium sulfate and concentrated. The residue was subjected to column chromatography on silica gel (dichloromethane: methanol 50: 1 to 25: 1) to give a pale yellow solid (3S, 5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (270 mg, yield: 83%). LCMS (ESI): m/z 396 [M+1] ⁺ ; TLC: Rf 0.5 (dichloromethane: methanol = 20: 1).

Step 24e: Preparation of (3S,5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (Compound 0122-100): A mixture of (3S,5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (0120-100) (270 mg, 0.68 mmol, 1.0 eq) in hydrogen chloride/methanol solution (4M solution, 2 ml) was stirred at room temperature for 2 hours. The solvent was removed under reduced pressure. The residue was dried under vacuum to give a pale yellow solid (3S,5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (270 mg, crude product). LCMS (ESI): m/z 296 [M+1] ⁺ ; TLC: Rf 0.3 (dichloromethane:methanol=10:1).

Step 24f: Preparation of (R)-1-((3R,5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'-H-spiro[pyrrolidin-3,2'-[1,8]naphthyridine]-1-yl)-2-(5-fluoro-2-methoxypyridin-4-yl)propan-1-one (Compound 100): to (R)-2-(5-fluoro-2-methoxypyridin-4-yl)propanoic acid (0406-7) (95 mg, 0.476 mmol, 1.0 equiv), 6-chlorobenzotriazole-1, To a mixture of 1,3,3-tetramethyluronium hexafluorophosphate (217 mg, 0.524 mmol, 1.1 eq) and N,N-diisopropylethylamine (196 mg, 1.523 mmol, 3.2 eq) in dichloromethane (7 ml) was added (3S,5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (0122-100) (175 mg, 0.476 mmol, 1.0 eq). The mixture was stirred at room temperature for 1.5 hours. The mixture was diluted with water (30 ml) and then extracted with ethyl acetate (15 ml×3). The combined organic layer was washed with saturated brine (15 ml), dried over anhydrous sodium sulfate and concentrated. The residue was purified by preparative thin layer chromatography (dichloromethane:methanol:aqueous ammonia=80:2.5:0.8) to give a white solid (R)-1-((3R,5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'-H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)-2-(5-fluoro-2-methoxypyridin-4-yl)propan-1-one (152 mg, yield: 67%). LCMS (ESI): m/z 477 [M+1] ⁺ ; TLC: Rf 0.5 (dichloromethane:methanol=15:1). ¹ H NMR (500MHz, MeOD) δ8.81 (d, J = 4.9 Hz, 2H), 7.93 (d, J = 31.5 Hz, 2H), 7.31 (t, J = 4.9 Hz, 1H),6.70(d,J＝4.8Hz,1H),4.46–4.30(m,1H),4.16(d,J＝6.9Hz,1H),3.88(d,J ＝9.9Hz,3H),3.73(d,J＝10.8Hz,1H),3.24(d,J＝11.0Hz,1H),2.90–2.68(m,2H), 2.57(d,J＝19.3Hz,3H), 2.33(dd,J＝12.7,8.2Hz,1H), 1.89(dd,J＝14.9,7.6Hz, 2H), 1.69 (dd, J＝13.2, 8.7Hz, 1H), 1.40 (d, J＝6.9Hz, 3H), 1.31 (d, J＝6.1Hz, 3H).

Example 25: Preparation of 4-(1-((3S,5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)-1-oxopropane-2-yl)-6-methoxynicotinonitrile (Compound 96) (prepared according to Scheme 4):

A mixture of (3S,5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3', ^4' -dihydro- _1'H -1λ2-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (0122-100) (88 mg, 0.24 mmol, 1.0 eq), 2-(5-cyano-2-methoxypyridin-4-yl)propanoic acid (0405-11) (59 mg, 0.29 mmol, 1.2 eq), N,N-diisopropylethylamine (186 mg, 1.44 mmol, 6.0 eq) and 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (110 mg, 0.29 mmol, 1.2 eq) in dichloromethane (4 ml) was stirred for one hour. The mixture was diluted with water and extracted with dichloromethane, and the organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by thick preparative thin layer chromatography (eluent: dichloromethane/methanol/ammonia water=80/4.5/0.8) to obtain a light yellow solid product 4-(1-((3S,5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)-1-oxopropane-2-yl)-6-methoxynicotinonitrile (20 mg, yield: 17.24%). LCMS (ESI): m/z=484[M+H] ⁺ . ¹ H NMR(500MHz,MeOD)δ8.82(dd,J＝14.2,4.9Hz,2H),8.32(d,J＝184.6Hz,1H),7.84(d,J＝22.5 Hz,1H),7.31(dt,J＝9.7,4.9Hz,1H),6.89(d,J＝31.8Hz,1H),4.45–4.32(m,1H),4.13(dd,J＝ 77.8,6.8Hz,1H),3.98(d,J＝6.6Hz,3H),3.71(dd,J＝74.4,10.3Hz,1H),3.51(dd,J＝40.4,10 .8Hz,1H),2.91–2.82(m,2H),2.52(d,J＝13.6Hz,3H),2.09–1.66(m,4H),1.49–1.34(m,6H).

Example 26: Preparation of (R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-((3S,5R)-5-(fluoromethyl)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'-pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 103):

Step 26a: Preparation of (9H-fluoren-9-yl)methyl (3S,5R)-5-(hydroxymethyl)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate: A solution of (3S,5R)-5-(hydroxymethyl)-1'-(4-methoxybenzyl)-7'-methyl-3',4'-dihydro-1'-H-pyrrolo[3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (500 mg, 1.10 mmol, 1.0 eq) in hydrogen chloride/dioxane (5 mL) was stirred at room temperature for one hour. The reaction was concentrated under vacuum. The residue was added with tetrahydrofuran (10 ml), 9-fluorenylmethyl chloroformate (424 mg, 1.66 mmol, 1.5 eq), triethylamine (335 mg, 3.30 mmol, 3.0 Equivalent). The mixture was then stirred at room temperature for two hours. The reaction solution was diluted with water and extracted with ethyl acetate, and the organic phase was dried and concentrated under reduced pressure. The residue was purified by silica gel column (petroleum ether/ethyl acetate = 10/1 to 3/1) to obtain a yellow solid product (9H-fluoren-9-yl)methyl (3S, 5R)-5-(hydroxymethyl)-7'-methyl-3', 4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (380 mg, yield: 75.55%). LCMS (ESI): m/z = 456 [M+1] ⁺ .

Step 26b: Preparation of (9H-fluoren-9-yl)methyl (3S,5R)-5-(fluoromethyl)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate: Under nitrogen protection, to a solution of (9H-fluoren-9-yl)methyl (3S,5R)-5-(hydroxymethyl)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (380 mg, 0.83 mmol, 1.0 equiv) in dichloromethane (5 ml) at 0°C was added diethylaminosulfur trifluoride (269 mg, 1.67 mmol, 2.0 equiv), and the mixture was stirred at 0°C for 1.0 hour. The reaction solution was diluted with water and extracted with dichloromethane, and the organic phase was dried and concentrated under reduced pressure. The residue was purified by silica gel column (dichloromethane/methanol=100/1 to 30/1) to obtain a yellow solid product (9H-fluoren-9-yl)methyl (3S,5R)-5-(fluoromethyl)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (278 mg, yield: 72.97%). LCMS (ESI): m/z=458[M+1] ⁺ .

Step 26c: Preparation of (9H-fluoren-9-yl)methyl (3S,5R)-6'-bromo-5-(fluoromethyl)-7'-methyl-3',4'-dihydro-1'-pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate: Under nitrogen protection at 0°C, add (9H-fluoren-9-yl)methyl (3S,5R)-5-(fluoromethyl)-7'-methyl-3',4'-dihydro-1'-pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate. 1,3-Dibromo-5,5-dimethylimidazolidine-2,4-dione (87 mg, 0.303 mmol, 0.5 eq) was added dropwise to a solution of 4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (278 mg, 0.61 mmol, 1.0 eq) in dichloromethane (5 ml), and the mixture was stirred at 0°C for 1.0 hour. The reaction solution was quenched with sodium carbonate solution and extracted with dichloromethane, and the organic phase was dried and concentrated under reduced pressure. The residue was purified by silica gel column (petroleum ether/ethyl acetate=5/1 to 2/1) to obtain a yellow solid product (9H-fluoren-9-yl)methyl (3S,5R)-6'-bromo-5-(fluoromethyl)-7'-methyl-3',4'-dihydro-1'-pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (230 mg, yield: 70.77%). LCMS (ESI): m/z=537[M+1] ⁺ .

Step 26d: Preparation of tert-butyl (3S,5R)-6'-bromo-5-(fluoromethyl)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate: A solution of (9H-fluoren-9-yl)methyl (3S,5R)-6'-bromo-5-(fluoromethyl)-7'-methyl-3',4'-dihydro-1'-pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylate (230 mg, 0.43 mmol, 1.0 eq) in piperidine/dichloromethane (1 mL/4 mL) was stirred at room temperature for 1 hour. The reaction solution was concentrated under vacuum. Di-tert-butyl dicarbonate (188 mg, 0.86 mmol, 2.0 eq) and tetrahydrofuran (5 mL) were added to the residue. The mixture was stirred at room temperature for one hour. The reaction solution was diluted with water and extracted with ethyl acetate, and the organic phase was dried and concentrated under reduced pressure. The residue was purified by silica gel column (petroleum ether/ethyl acetate = 5/1 to 2/1) to obtain a yellow oily product (3S, 5R)-6'-bromo-5-(fluoromethyl)-7'-methyl-3', 4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (150 mg, yield: 84.75%). LCMS (ESI): m/z = 414 [M+1] ⁺ .

Step 26e: Preparation of (3S,5R)-5-(fluoromethyl)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'-H-pyrrolo[3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester: Under nitrogen protection, (3S,5R)-6'-bromo-5-(fluoromethyl)-7'-methyl-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (150 mg, 0.36 mmol, 1.0 equiv), 2-(tributyltinyl)pyrimidine (268 mg, 0.72 mmol, 2.0 eq), cuprous iodide (7 mg, 0.036 mmol, 0.1 eq), methanesulfonic acid (2-dicyclohexylphosphino-2',4',6'-tri-isopropyl-1,1'-biphenyl)(2'-amino-1,1'-biphenyl-2-yl) palladium (II) (16 mg, 0.018 mmol, 0.05 eq), 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (18 mg, 0.036 mmol, 0.1 eq), cesium fluoride (111 mg, 0.72 mmol, 3.0 eq) in N,N-dimethylformamide (5 ml) was heated in a microwave at 100° C. for 1.5 hours. The reaction solution was diluted with water and extracted with ethyl acetate, and the organic phase was dried and concentrated under reduced pressure. The residue was purified by silica gel column (petroleum ether/ethyl acetate = 5/1 to 2/1) to obtain a yellow solid product (3S,5R)-5-(fluoromethyl)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'-H-pyrrolo[3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (64 mg, yield: 42.67%). LCMS (ESI): m/z = 414 [M+1] ⁺ .

Step 26f: Preparation of (3S,5R)-5-(fluoromethyl)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'-H-pyrrolo[3,2'-[1,8]naphthyridine] dihydrochloride: A mixture of (3S,5R)-5-(fluoromethyl)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'-H-pyrrolo[3,2'-[1,8]naphthyridine]-1-carboxylic acid tert-butyl ester (64 mg, 0.15 mmol, 1.0 eq) in hydrogen chloride dioxane solution (4 M solution, 2.5 mL) was stirred at room temperature for 1.0 h, the solvent was removed under reduced pressure and dried under vacuum, and the residue was used directly in the next step without further purification. LCMS (ESI): m/z=314[M+1] ⁺ .

Step 26g: Preparation of (R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-((3S,5R)-5-(fluoromethyl)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'-pyrrolidin-3,2'-[1,8]naphthyridin]-1-yl)propan-1-one (Compound 103): To (R)-2-(5-fluoro-2-methoxypyridin-4-yl)propanoic acid (0406-7) (31 mg, 0.155 mmol, 1.0 equiv), (3S,5R)-5-(fluoromethyl)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'-pyrrolidin-3,2'-[1,8]naphthyridin]-1-yl)propan-1-one was added. 6-Chlorobenzotriazole-1,1,3,3-tetramethyluronium hexafluorophosphate (77 mg, 0.186 mmol, 1.2 eq.) was added to a solution of 5-(fluoromethyl)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'-H-pyrrolo[3,2'-[1,8]naphthyridine] dihydrochloride (crude product) and N,N-diisopropylethylamine (50 mg, 0.388 mmol, 2.5 eq.) in dichloromethane (3 ml), and the mixture was stirred at room temperature for 1.0 hour. The reaction solution was diluted with water and extracted with dichloromethane, and the organic phase was dried and concentrated under reduced pressure. The residue was purified by preparative thin layer chromatography (dichloromethane/methanol=20/1) to give a yellow solid product (R)-2-(5-fluoro-2-methoxypyridin-4-yl)-1-((3S,5R)-5-(fluoromethyl)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'-pyrrolidin-3,2'-[1,8]naphthyridin]-1-yl)propan-1-one (32 mg, yield 42.11%). LCMS (ESI): m/z=495[M+1] ⁺ . ¹ H NMR (500MHz, MeOD) δ8.82(t,J＝6.2Hz,2H),7.96(s,1H),7.86(s,1H),7.30(t,J＝4.9Hz,1H),6.69( d,J＝4.9Hz,1H),4.93(dd,J＝9.3,3.2Hz,1H),4.61–4.37(m,2H),4.20(q,J＝6.8Hz,1H),3.88(d,J＝1 3.8Hz,3H),3.76(d,J＝10.7Hz,1H),3.13(d,J＝10.8Hz,1H),2.93–2.72(m,2H),2.56(d,J＝16.9Hz, 3H),2.31–2.15(m,1H),2.10(dd,J＝13.3,9.0Hz,1H),1.90(t,J＝6.4Hz,2H),1.41(d,J＝6.9Hz,3H).

Example 27: Preparation of 2-(5-chloro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propane-1-thione (Compound 10) (prepared according to Schemes 4 and 5):

Step 27a: Preparation of methyl 2-(5-chloro-2-methoxypyridin-4-yl)acetate (0409-10): Under nitrogen protection, to a solution of diisopropylamine (1.23 g, 12.22 mmol, 3.2 eq.) in tetrahydrofuran (5 ml) at -30°C was added dropwise n-butyllithium in n-hexyl After the mixture was stirred at -30°C for 1 hour, a tetrahydrofuran solution (1 ml) of 5-chloro-2-methoxy-4-methylpyridine (0408-10) (600 mg, 3.82 mmol, 0.2 eq) was added dropwise to the mixture. After the mixture was stirred at -30°C for 1 hour, dimethyl carbonate (1.03 g, 11.46 mmol, 3 eq) was added dropwise. After the addition, the mixture was warmed to room temperature and stirred for 1 hour. The reaction solution was quenched with water and extracted with ethyl acetate. The organic phase was washed with saturated brine, dried with sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by silica gel column (petroleum ether/ethyl acetate = 10/1) to obtain 2-(5-chloro-2-methoxypyridin-4-yl)acetic acid methyl ester (600 mg, yield: 73.08%) as a transparent oily product. LCMS (ESI): m/z=216[M+1] ⁺ .

Step 27b: Preparation of methyl 2-(5-chloro-2-methoxypyridin-4-yl)propanoate (Compound 0410-10): To a solution of methyl 2-(5-chloro-2-methoxypyridin-4-yl)acetate (0409-10) (550 mg, 2.56 mmol, 1 eq) in tetrahydrofuran (5 ml) at 0°C was added lithium bis(trimethylsilyl)amide (1 M in tetrahydrofuran, 2.86 ml, 2.86 mmol, 1.2 eq). The mixture was stirred at 0°C for 1 hour, and then a solution of iodomethane (327 mg, 2.3 mmol, 0.9 eq) in tetrahydrofuran (1 ml) was added dropwise at 0°C. The mixture was stirred at 0°C for 1 hour. The mixture was then poured into a saturated aqueous ammonium chloride solution and extracted with ethyl acetate. The organic phase was washed with saturated brine, dried over sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by silica gel column (petroleum ether/ethyl acetate = 10/1) to obtain methyl 2-(5-chloro-2-methoxypyridin-4-yl)propanoate (320 mg, yield: 54.61%) as a yellow oily product. LCMS (ESI): m/z = 230 [M+1] ⁺ .

Step 27c: Preparation of 2-(5-chloro-2-methoxypyridin-4-yl)propanoic acid (Compound 0405-10): To a solution of methyl 2-(5-chloro-2-methoxypyridin-4-yl)propanoate (0410-10) (320 mg, 1.4 mmol, 1 eq) in tetrahydrofuran/water (5/1 ml) was added lithium hydroxide monohydrate (12 mg, 0.28 mmol, 0.2 eq). The mixture was stirred at room temperature overnight and then concentrated under reduced pressure. The aqueous residue was poured into water and washed with methyl tert-butyl ether. The pH of the aqueous layer was then adjusted to 4 by the addition of 3M hydrochloric acid and extracted with ethyl acetate. The organic phase was washed with saturated brine, dried over sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by silica gel column (eluent: dichloromethane/methanol = 20/1) to obtain 2-(5-chloro-2-methoxypyridin-4-yl)propanoic acid (106 mg, yield: 35.33%) as a transparent oily product. LCMS (ESI): m/z = 216 [M+1] ⁺ .

Step 27d: Preparation of 2-(5-chloro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidin-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 0412-10): 2-(5-chloro-2-methoxypyridin-4-yl)propanoic acid (0405-10) (18 mg, 0.085 mmol, 1 eq), (S)-7'-methyl-6'-(pyrimidin-2 2-(7-azobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (36 mg, 0.094 mmol, 1.1 eq) was added to a solution of 1,2-dihydro- ... The residue was purified by preparative thin layer chromatography (dichloromethane/methanol=20/1) to give 2-(5-chloro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (12 mg, yield: 30%) as a yellow oily product. LCMS (ESI): m/z=479[M+1] ⁺ .

Step 27e: Preparation of 2-(5-chloro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propane-1-thione (Compound 10): 2-(5-chloro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propane-1-thione A mixture of '-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (0412-10) (36 mg, 0.075 mmol, 1.0 eq) and Lawesson's reagent (36 mg, 0.09 mmol, 1.2 eq) was stirred and heated in a microwave at 125°C for 45 minutes. The reaction was cooled to room temperature and quenched with water. The reaction solution was extracted with ethyl acetate, and the organic phase was dried and concentrated under reduced pressure. The residue was purified by preparative thin layer chromatography (dichloromethane/methanol/aqueous ammonia=80/4.5/0.8) to give 2-(5-chloro-2-methoxypyridin-4-yl)-1-((S)-7'-methyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propane-1-thione (21 mg, yield: 56.3%) as a yellow solid. LCMS (ESI): m/z=495[M+1] ⁺ . ¹ H NMR(500MHz,MeOD)δ8.81(t,J＝5.0Hz,2H),8.03(t,J＝43.5Hz,1H),7.86(dd,J＝13.1,9 .3Hz,1H),7.32–7.23(m,1H),6.94(dd,J＝15.6,13.9Hz,1H),4.57–4.37(m,1H),4.14– 3.93(m,2H),3.91–3.85(m,3H),3.86–3.57(m,2H),2.96–2.72(m,2H),2.57(dd,J＝9.6 ,4.8Hz,3H),2.31–2.08(m,2H),2.06–1.75(m,2H),1.54(ddd,J=15.7,9.2,6.9Hz,3H).

Example 28: Preparation of 2-(5-chloro-2-methoxypyridin-4-yl)-1-((3S,5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 104):

(3S,5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (0122-100) (66 mg, 0.181 mmol, 1.0 equiv), 2-(5-chloro-2-methoxypyridin-4-yl)propanoic acid (0405-10) (38 mg, 0.181 mmol, 1.0 equiv) A mixture of 1-hydroxybenzotriazole (29 mg, 0.217 mmol, 1.2 eq.), N,N-diisopropylethylamine (94 mg, 0.724 mmol, 4.0 eq.), 1-hydroxybenzotriazole (29 mg, 0.217 mmol, 1.2 eq.), benzotriazole-N,N,N',N'-tetramethyluronium hexafluorophosphate (82 mg, 0.217 mmol, 1.2 eq.) in dichloromethane (2 ml) was stirred at room temperature for 2 hours. The reaction solution was diluted with water (15 ml) and extracted with ethyl acetate (5 ml x 3). The organic phase was washed with saturated brine (15 ml), dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was purified by thick preparative thin layer chromatography (dichloromethane/methanol=8/1) to give a white solid product 2-(5-chloro-2-methoxypyridin-4-yl)-1-((3S,5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (48.3 mg, yield: 97.3%). LCMS (ESI): m/z=494[M+1] ^{+ .1} HNMR(500MHz,MeOD)δ8.82(dd,J＝6.9,5.0Hz,2H),8.18–7.70(m,2H),7.31(t,J＝4.0Hz ,1H),6.76(d,J＝54.1Hz,1H),4.38(dd,J＝14.4,7.8Hz,1H),4.16(dd,J＝38.3,6.9Hz,1 H),3.89(d,J＝4.2Hz,3H),3.72–3.32(m,2H),2.91–2.69(m,2H),2.31(ddd,J＝21.4,12 .6,7.9Hz,1H),1.98–1.61(m,3H),1.38(d,J＝6.6Hz,3H),1.34(dd,J＝16.4,6.6Hz,3H).

Example 29: Preparation of (R)-2-(5-chloro-2-methoxypyridin-4-yl)-1-((3S,5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 105) (Prepared according to Schemes 1 and 4)

Step 29a: Preparation of (R)-2-(5-chloro-2-methoxypyridin-4-yl)propanoic acid: Separation of enantiomers of 2-(5-chloro-2-methoxypyridin-4-yl)propanoic acid (0405-10) (12.5 g, 57.98 mmol) was carried out by supercritical fluid chromatography (chromatographic column: ChiralPak IG, 300×50 mm I.D., 10 μm; mobile phase: A is carbon dioxide, B is methanol; gradient: 15% B; flow rate: 200 ml/min; back pressure: 100 bar; column temperature: 38°C). The first eluting enantiomer was (R)-2-(5-chloro-2-methoxypyridin-4-yl)propionic acid (5.29 g, yield: 42%), and the second eluting enantiomer was (S)-2-(5-chloro-2-methoxypyridin-4-yl)propionic acid (4.81 g, yield: 38%). Analysis conditions: Column: ChiralPak IG, 100×4.6 mm I.D., 3 μm; Mobile phase: A is carbon dioxide, B is methanol (0.05% diethylamine); Gradient: 5-40% B; Flow rate: 2.5 ml/min; Back pressure: 100 bar; Column temperature: 35°C.

Step 29b: Preparation of (R)-2-(5-chloro-2-methoxypyridin-4-yl)-1-((3S,5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidin-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (Compound 105): At 0°C, (R)-2-(5-chloro-2-methoxypyridin-4-yl)propanoic acid (154 mg, 0.712 mmol, 1.05 equiv), (3S,5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidin-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one were added. '-Dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine] dihydrochloride (0122-100) (247 mg, 0.678 mmol, 1.0 eq), N-methylimidazole (228 mg, 2.78 mmol, 4.1 eq) were added to a mixture of acetonitrile (2 ml) and dichloromethane (2 ml) with N,N,N',N'-tetramethylchloroformamidine hexafluorophosphate (247 mg, 0.881 mmol, 1.3 eq). The mixture was stirred at 0°C for 1.5 hours. The mixture was diluted with water (30 ml) and then extracted with ethyl acetate (20 ml×3). The combined organic layer was washed with saturated brine (20 ml), dried over anhydrous sodium sulfate and concentrated. The residue was subjected to column chromatography on silica gel (dichloromethane: methanol 30: 1) to give a white solid (R)-2-(5-chloro-2-methoxypyridin-4-yl)-1-((3S,5S)-5,7'-dimethyl-6'-(pyrimidin-2-yl)-3',4'-dihydro-1'H-spiro[pyrrolidine-3,2'-[1,8]naphthyridine]-1-yl)propan-1-one (290 mg, yield: 84% ⁾ . LCMS (ESI): m/z 493 [M+1] ⁺ ; TLC: Rf 0.5 (ethyl acetate: dichloromethane = 1:1). NMR(500MHz,MeOD)δ8.82(d,J＝4.9Hz,2H),8.12(s,1H),7.92(s,1H),7.31(t,J＝4.9Hz,1H),6.71(s ,1H),4.38(d,J＝6.4Hz,1H),4.20(d,J＝6.9Hz,1H),3.89(s,3H),3.69(d,J＝10.9Hz,1H),3.22(d,J＝ 11.0Hz,1H),2.81(ddd,J＝24.1,14.6,7.9Hz,2H),2.61(s,3H),2.34(dd,J＝13.2,7.8Hz,1H),1.90( dd,J＝13.4,7.3Hz,2H),1.70(dd,J＝13.3,8.6Hz,1H),1.38(d,J＝6.8Hz,3H),1.33(d,J＝6.2Hz,3H).

Example 30 Biological Activity Test

The reference compound used in the present invention is PF-07258669 (Journal of Medicinal Chemistry, 66 (5), 3195-3211, 2023, WO 2021250541), and its structure is as follows:

1. MC4R Antagonist Activity

The time-resolved fluorescence resonance energy transfer (TR-FRET) method was used to detect the antagonistic activity of the test compound on human melanocortin-4-receptor (MC4R) stably expressed in cell lines.

1 Experimental materials and instruments

2 Experimental steps

2.1 Preparation and handling of test compounds

2.1.1 Preparation of stock solutions of test compounds

1) The test compound was dissolved in DMSO to prepare a 10 mM stock solution;

2) Melanotan I was dissolved in H ₂ O to prepare a 1 mM stock solution.

2.1.2 Storage of compound stock solutions

After the compound was dissolved, it was stored in a -20°C refrigerator.

2.1.3 Preparation of working solution

1) The test compound was diluted 5-fold with DMSO, with 10 or 5 concentration gradients;

2) Configure Melanotan I assay buffer to 800 pM for use.

2.2 Determination of the antagonistic activity of the test compounds on MC4R

2.2.1 Cell lines, culture media and buffers

1) Cell line: Flp-In-293-Human MC4R

Complete culture medium: DMEM + 10% fetal bovine serum + 1% penicillin-streptomycin + 200 μg/mL hygromycin

2) Experimental buffer: HBSS + 20 mM HEPES + 10% FBS + 500 μM IBMX

2.2.2 Cell culture and plating

1) Flp-In-293-MC4R was cultured in complete medium at 37°C and 5% _CO2 .

2) After trypsin digestion, the cells were resuspended in the experimental buffer and inoculated into 384 cell culture plates at a density of 2000 per well and a volume of 15 μl per well.

2.2.3 Determination of the activity of the test compounds on Human MC4R receptor

1) Add 2.5 μl of 8X diluted test compound to each well and incubate at 37°C for 10 minutes.

2) Add 2.5 μl of diluted 8X Melanotan I (800 pM) to each well and incubate at 37°C for 30 minutes.

3) Freeze-thaw Eu-cAMP tracer and Ulight-anti-cAMP, and dilute them with lysis buffer.

4) First add 10μl Eu-cAMP tracer to the experimental well, and then add 10μl Ulight-anti-cAMP to the experimental well.

5) The reaction plate was centrifuged at 1000 g for 1 min at room temperature and allowed to stand at 25°C for 1 h. Data were collected using Envision, with excitation light at 340 nm and emission light at 665 nm and 615 nm.

2.3 Data Analysis

1) The ratio of the acceptor and donor excitation signals in each single well was calculated using the formula Ratio = Signal 665nm/Signal 620nm, and the inhibition rate at different concentrations was calculated. The IC ₅₀ of the compound was calculated using the GraphPad nonlinear fitting formula:

Y＝Bottom﹢(Top﹣Bottom)/(1﹢10^((LogIC ₅₀ ﹣X)×HillSlope))

X: log value of compound concentration; Y: Inhibition%

3. Experimental results

The half maximal inhibitory concentration (IC ₅₀ ) of each compound in the above experiment was calculated. The results are shown in Table 1.

Table 1. Antagonistic activity of compounds on MC4R

2. Pharmacokinetic (PK) Experiment

1. Experimental Methods

Female C57 mice weighing 18-20 g. The test compound was dissolved in 30% sulfobutyl β-cyclodextrin and administered orally at 10 mg/kg. Blood was collected from the heart of the mice at 15 minutes, 30 minutes, and 1, 2, 4, 7, and 24 hours after administration. The mice were then euthanized and brain tissue was collected. About 0.3 ml of whole blood and 50-100 mg of brain tissue were collected at each time point. The whole blood was placed in a centrifuge tube containing K ₂ -EDTA and centrifuged (3000 g, 10 minutes, 4°C) to collect plasma. The plasma and brain tissue were stored at -40°C for later use. The brain tissue weighed in advance was homogenized with 0.9% NaCl solution at a ratio of 1:3 (g/ml). 50 μL of plasma sample or brain tissue homogenate was vortexed with 135 μL of acetonitrile (containing internal standard 0.1 μg/mL) for protein precipitation, centrifuged, and the supernatant was taken for LC-MS/MS analysis.

2. Experimental results

The compounds 100 and 104 provided by the present invention are well absorbed after oral administration to mice, and the exposure to blood and brain is high. The results are shown in Figures 1-2 and Table 2. The spiro heterocyclic compound of the present invention has a T _max of 0.25 hours in plasma, a C _max of 1243.33-1593.33 ng/ml, and an AUC _0-24 of 1448.77-1649.36 hr*ng/mL, a T _max of 0.25-0.50 hours in the brain, a C _max of 413.20-512.00 ng/ml, and an AUC _0-24 of 435.13-633.25 hr*ng/mL. Compared with the control compound PF07258669, the compound of the present invention has better pharmacokinetic properties in the brain and has greater therapeutic potential in treating MC4 receptor-related diseases and/or symptoms such as cachexia, anorexia, etc. _Cmax refers to the maximum plasma concentration, T1 _/2 is the half-life, _AUC0-24 refers to the area under the 0-24 hour time-concentration curve, and AUC0 _-inf refers to the area under the 0-Inf time-concentration curve.

Table 2. Pharmacokinetic parameters of oral administration in mice (10 mg/kg)

3. In vitro metabolic stability test

1. Experimental Methods

Dissolve the test compound in DMSO and dilute it with acetonitrile. Add 2 μL of acetonitrile to dilute the test compound and 300 μL of potassium phosphate buffer containing human liver microsomes to the centrifuge tube. After mixing, transfer 30 μL to 6 centrifuge tubes respectively. After preheating at 37°C for 10 minutes, add 15 μL of 6 mM NADPH solution (except 0 point) and mix. After incubation for 30 minutes and 60 minutes, add 135 μL of acetonitrile (containing 0.1 μg/ml internal standard) solution to terminate the reaction. For the 0-minute sample, first add 135 μL of acetonitrile (containing 0.1 ug/ml internal standard) to terminate the reaction and then add 15 μL of 6 mM NADPH solution (two samples for each time point). After mixing, centrifuge at 15000g for 10 minutes, and take the supernatant for LC-MS/MS analysis.

The experimental results were characterized by half-life (T _1/2 )=0.693/K (K is the rate constant obtained by linear regression with the logarithm of the relative residual percentage of the test compound as the ordinate and the incubation time as the abscissa).

2. Experimental results

The half-life (T _1/2 ) of each compound in the above experiment was calculated, and the results are shown in Table 3. The results show that compound 100 and compound 105 have better metabolic stability in human liver microsomes than PF07258669 and longer metabolic half-life, suggesting that the drug elimination half-life of the compounds of the present invention in the human body will be longer, thereby reducing the frequency of administration.

Table 3 Metabolic stability results of compounds in human liver microsomes

The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims (28)

A spiroheterocyclic compound having a structure represented by formula (I) or a pharmaceutically acceptable salt thereof or a stereoisomer thereof or a deuterated product thereof or a prodrug molecule thereof:
in: R ₁ , R ₂ , R ₃ and R ₄ are independently selected from the group consisting of H, deuterium, C ₁ -C ₆ alkyl, C ₁ -C ₆ deuterated alkyl, C ₂ -C ₆ alkenyl, C ₂ -C ₆ alkynyl, C ₃ -C ₈ cycloalkyl, halogen-substituted C ₃ -C ₈ cycloalkyl, C ₃ -C ₈ cycloalkylmethyl, halogen, halogen-substituted C ₁ -C ₆ alkyl, hydroxy, hydroxy-substituted C ₁ -C ₆ alkyl, C ₁ -C ₆ alkoxy-substituted C ₁ -C ₆ alkyl, cyano, -OR, -N(R) ₂ , -SR, -C(O)OR, -C(O)N(R) ₂ , -C(O)R, -S(O)R, -S(O) ₂ R, -S(O) ₂ N(R) ₂ , -N(R)C(O)R; R is selected from the group consisting of: H, C ₁ -C ₆ alkyl, C ₂ -C ₆ alkenyl, C ₂ -C ₆ alkynyl, C ₃ -C ₈ cycloalkyl, C ₃ -C ₈ cycloalkylmethyl, halogen-substituted C ₁ -C ₆ alkyl, hydroxy-substituted C ₁ -C ₆ alkyl, alkoxy-substituted C ₁ -C ₆ alkyl, amino-substituted C ₁ -C ₆ alkyl, alkylamino-substituted C ₁ -C ₆ alkyl; R ₅ and R ₆ are independently selected from: H, deuterium, halogen; M is selected from: CH, N; W is selected from: O, S, NR ₇ ; Q is selected from the group consisting of: CR ₇ R ₈ , NR ₈ , C═O, O, S, or absent; _R7 and _R8 are independently selected from the group consisting of: H, deuterium, halogen, _C1 - _C6 alkyl, _{C1 - C6} deuterated alkyl, C2- _C6 alkenyl, C2 _{- C6} alkynyl, _C3 - _C8 cycloalkyl, halogen-substituted _C1 - _C6 alkyl, halogen-substituted _C3 - _C8 cycloalkyl, hydroxyl, cyano, amino, _C1 - _C6 alkylamino; or _R8 and the substituents in A are linked to form a substituted or unsubstituted 5-7 membered carbocyclic or heterocyclic ring; A is selected from: C ₆ -C ₁₀ membered aryl substituted or unsubstituted by R ₉ and R ₁₀ , 5-10 membered heteroaryl substituted or _{unsubstituted} by R ₉ and R 10, 7-10 membered benzoheterocyclyl substituted or unsubstituted by R ₉ and R ₁₀ ; Each _R9 and _R10 is independently selected from the group consisting of H, deuterium, halogen, _C1 - _{C6 alkyl} , _C1 - _C6 deuterated alkyl, _{C2 - C6} alkenyl, _C2 - _C6 alkynyl, _cyano , _C3 - _C8 cycloalkyl, _C3 - _C8 deuterated cycloalkyl, C3- _C8 cycloalkylC1- _C6 alkyl, _{C1 -} C6 alkylsulfonyl, C1- _{C6 alkylthio, C1-C6 deuterated alkylthio, C3-C8 cycloalkylthio , halogen} -substituted C1 _{- C6} alkyl, _C1 - _C6 alkoxy, _C1 - _C6 deuterated alkoxy, halogen-substituted C1 _{- C6} alkoxy, _{C3 - C8} cycloalkyloxy, _{C3-C8 deuterated} cycloalkyloxy, halogen-substituted _C3 -C6 ₈ -cycloalkyloxy, carbamoyl; _A1 is selected from: phenyl substituted or unsubstituted by _R11 and _R12 , 5-6 membered heteroaryl substituted or unsubstituted by _R11 and _R12 ; Each of R _n and R ₁₂ is independently selected from the group consisting of: H, deuterium, halogen, C ₁ -C ₆ alkyl, C ₁ -C ₆ deuterated alkyl, C ₃ -C ₈ cycloalkyl, halogen-substituted C ₁ -C ₆ alkyl, cyano, and C ₁ -C ₆ alkoxy. The spiroheterocyclic compound or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or its prodrug molecule according to claim 1, characterized in that A is selected from: naphthyl substituted or unsubstituted by R ₉ and R ₁₀ , 9-10 membered heteroaryl substituted or unsubstituted by R ₉ and R ₁₀ , 9-10 membered benzoheterocyclic group substituted or unsubstituted by R ₉ and R ₁₀ . The spiroheterocyclic compound or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or its prodrug molecule according to claim 1, characterized in that A is selected from:
Among them: the dotted line in the ring represents whether it is a C-C single bond or not; X ₁ , X ₂ , and X ₃ are independently selected from the group consisting of CR ₉ , N. The spiroheterocyclic compound or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or its prodrug molecule according to claim 3, characterized in that A is selected from:
The spiroheterocyclic compound or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or its prodrug molecule according to claim 4, characterized in that A is selected from: W is O. The spiroheterocyclic compound according to any one of claims 1 to 5, or a pharmaceutically acceptable salt thereof, or a stereoisomer thereof The invention relates to a construct or a deuterated product thereof or a prodrug molecule thereof, characterized in that each R ₉ and R ₁₀ is independently selected from the group consisting of H, deuterium, halogen, C ₁ -C ₃ alkyl, C ₁ -C ₃ deuterated alkyl, C ₂ -C ₃ alkenyl, C ₂ -C ₃ alkynyl, cyano, C ₃ -C ₆ cycloalkyl, C ₃ -C ₆ deuterated cycloalkyl, C ₃ -C ₆ cycloalkylmethyl, C ₁ -C ₃ alkylsulfonyl, C ₁ -C ₃ alkylthio, C ₁ -C ₃ deuterated alkylthio, C ₃ -C ₆ cycloalkylthio, halogen-substituted C ₁ -C ₃ alkyl, C ₁ -C ₃ alkoxy, C ₁ -C ₃ deuterated alkoxy, halogen-substituted C ₁ -C ₃ alkoxy, C ₃ -C ₆ cycloalkyloxy, C ₃ -C _6- deuterated cycloalkyloxy, halogen-substituted C ₃ -C ₆ cycloalkyloxy, carbamoyl. The spiroheterocyclic compound or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or its prodrug molecule according to claim 6, characterized in that each R ₉ and R _i0 is independently selected from: hydrogen, methoxy, fluorine, difluoromethyl, difluoromethoxy, cyano, methyl, ethynyl, carbamoyl, methylsulfonyl, cyclopropyloxy, methylthio, and chlorine. The spiroheterocyclic compound or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or its prodrug molecule according to claim 3, characterized in that A is selected from:
The spiroheterocyclic compound or a pharmaceutically acceptable salt thereof or a stereoisomer thereof or a deuterated product thereof or a prodrug molecule thereof according to any one of claims 1 to 5, characterized in that each R ₁₁ and R ₁₂ is independently selected from: H, deuterium, halogen, C ₁ -C ₃ alkyl, C ₁ -C ₃ deuterated alkyl, C ₃ -C ₆ cycloalkyl, halogen-substituted C ₁ -C ₃ alkyl, cyano, C ₁ -C ₃ alkoxy. The spiroheterocyclic compound or a pharmaceutically acceptable salt thereof or a stereoisomer thereof or a deuterated product thereof or a prodrug molecule thereof according to any one of claims 1 to 5, characterized in that A ₁ is selected from:
The spiroheterocyclic compound or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or its prodrug molecule according to claim 10, characterized in that A ₁ is selected from:
The spiroheterocyclic compound or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or its prodrug molecule according to any one of claims 1 to 5, characterized in that W is selected from: S, NR ₇ ; Wherein, _R7 in W is selected from the group consisting of: H, _C1 - _C6 alkyl, _C1 - _C6 deuterated alkyl, _C3 - _C8 cycloalkyl, halogen-substituted C1 _{- C6} alkyl, and halogen-substituted _C3 - _C8 cycloalkyl. The spiroheterocyclic compound or a pharmaceutically acceptable salt thereof or a stereoisomer thereof or a deuterated product thereof or a prodrug molecule thereof according to any one of claims 1 to 5, characterized in that _R7 and _R8 are independently selected from: H, deuterium, halogen, _C1 - _C3 alkyl, C1- _C3 deuterated alkyl, _C2 - _{C3 alkenyl, C2-C3 alkynyl , C3 - C6} cycloalkyl, halogen-substituted C1 _{- C3} alkyl, halogen-substituted C3 _{-C6 cycloalkyl} , hydroxyl, cyano, amino, _C1 - _C3 alkylamino; or _R8 and the substituent in A are connected to form a substituted or unsubstituted 5-6-membered carbocyclic or heterocyclic ring. The spiroheterocyclic compound or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or its prodrug molecule according to claim 13, characterized in that _R7 and _R8 are independently selected from: H, deuterium, methyl, hydroxyl, cyano, vinyl, ethynyl, amino, deuterated methyl, or _R8 and the substituent in A are connected to form a 5-6 membered carbocyclic or heterocyclic ring. The spiroheterocyclic compound or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or its prodrug molecule according to any one of claims 1 to 5, characterized in that Q is selected from: -N(CH ₃ )-, The spiroheterocyclic compound or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or its prodrug molecule according to any one of claims 1 to 5, characterized in that _R4 is selected from: _C1 - _C6 alkyl, _C1 - _C6 deuterated alkyl, halogen-substituted _C1 - _C6 alkyl. The spiroheterocyclic compound or a pharmaceutically acceptable salt thereof or a stereoisomer thereof or a deuterated product thereof or a prodrug molecule thereof according to any one of claims 1 to 5, characterized in that R ₁ , R ₂ , R ₃ and R ₄ are independently selected from the group consisting of: H, deuterium, C ₁ -C ₃ alkyl, C ₁ -C ₃ deuterated alkyl, C ₂ -C ₄ alkenyl, C ₂ -C ₄ alkynyl, C ₃ -C ₆ cycloalkyl, halogen-substituted C ₃ -C ₆ cycloalkyl, C ₃ -C ₆ cycloalkylmethyl, halogen, halogen-substituted C ₁ -C ₃ alkyl, OH, hydroxy-substituted C ₁ -C ₃ alkyl, alkoxy-substituted C ₁ -C ₃ alkyl, and cyano. The spiroheterocyclic compound or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or its prodrug molecule according to claim 17, characterized in that _R1 is selected from: methyl, hydroxyl, difluoromethyl, trifluoromethyl, cyano, chlorine, fluorine, vinyl, ethynyl, cyclopropyl, deuterated methyl. The spiroheterocyclic compound or a pharmaceutically acceptable salt thereof or a stereoisomer thereof or a deuterated product thereof or a prodrug molecule thereof according to any one of claim 17, characterized in that _R2 is selected from: H, fluorine, methyl, chlorine, deuterium. The spiroheterocyclic compound or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or its prodrug molecule according to any one of claim 17, characterized in that R ₃ is selected from: H, fluorine. The spiroheterocyclic compound or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or its prodrug molecule according to any one of claim 17, characterized in that _R4 is selected from: H, methyl, methoxymethyl, monofluoromethyl. The spiroheterocyclic compound or its pharmaceutically acceptable salt or its stereoisomer or its deuterated product or its prodrug molecule according to claim 1, characterized in that it is selected from the following compounds:





Use of the spiroheterocyclic compound according to any one of claims 1 to 22, or a pharmaceutically acceptable salt thereof, or a stereoisomer thereof, or a deuterated product thereof, or a prodrug molecule thereof in the preparation of an MC4 receptor antagonist. Use of the spiroheterocyclic compound according to any one of claims 1 to 22, or a pharmaceutically acceptable salt thereof, or a stereoisomer thereof, or a deuterated product thereof, or a prodrug molecule thereof, in the preparation of a medicament for preventing and/or treating diseases and/or symptoms associated with the MC4 receptor. The use according to claim 24 is characterized in that the diseases and/or symptoms associated with the MC4 receptor are selected from: cachexia, anorexia, nausea, vomiting, involuntary weight loss, sarcopenia, muscle atrophy, muscle weakness, asthenia, bone diseases, pain or neuropathic pain, anxiety, sexual dysfunction, and inflammatory diseases. The use according to claim 25 is characterized in that the cachexia includes cachexia associated with chronic diseases, cancer, acquired immunodeficiency syndrome, heart failure and/or chronic kidney disease; the anorexia includes anorexia nervosa, senile anorexia, and anorexia associated with chemotherapy and radiotherapy; the bone disease includes bone loss; the anxiety includes post-traumatic stress disorder, PTSD; the inflammatory disease includes inflammatory diseases associated with cachexia, anorexia, and sarcopenia. A pharmaceutical composition for preventing and/or treating diseases and/or symptoms associated with MC4 receptors, characterized in that it comprises an active ingredient and a pharmaceutically acceptable excipient, wherein the active ingredient comprises a spiroheterocyclic compound according to any one of claims 1 to 22, or a pharmaceutically acceptable salt thereof, or a stereoisomer thereof, or a deuterated product thereof, or a prodrug molecule thereof. A method for preventing and/or treating diseases and/or symptoms associated with MC4 receptors, characterized in that the method comprises: administering a safe and effective amount of the spiroheterocyclic compound according to any one of claims 1 to 22, or a pharmaceutically acceptable salt thereof, or a stereoisomer thereof, or a deuterated substance thereof, or a prodrug molecule thereof; and/or, Administer a safe and effective amount of the pharmaceutical composition of claim 27.