WO2024260259A1 - Integrin ligand and use thereof - Google Patents

Abstract

The present invention provides a compound as represented by the following formula I, a tautomer thereof, or a pharmaceutically acceptable salt thereof. The compound has serum stability and affinity for integrin αvβ6, has a good inhibitory effect on the integrin αvβ6, and thus has an inhibitory effect on tumor growth.

Description

Integrin ligand and use thereof Technical Field

The present invention belongs to the field of biomedicine, and specifically relates to an integrin ligand and a use thereof.

Background Art

Tumors are one of the important causes of death from diseases. Studies have found that the tumor microenvironment plays an important role in the occurrence and metastasis of tumor cells. Among them, the adhesion molecule family is an important molecule that plays a key role in the tumor microenvironment. Integrin is one of the surface cell adhesion molecules, which is composed of α-methylene (18 types) and β-subunits (8 types) to form 24 different integrins. Integrin αvβ6 is an αvβ6 heterodimer formed by the combination of integrin αv and integrin β6. The main structure is three domains: cytoplasmic domain, extracellular domain and transmembrane domain. Existing studies have shown that αvβ6 integrin can promote cell invasion and migration in metastasis and inhibit cell apoptosis. αvβ6 integrin can also regulate the expression of matrix metalloproteinases (MMPs) and activate TGF-β1. More and more major evidence from in vitro studies shows that αvβ6 integrin may promote cancer progression. Therefore, considering the role of integrin αvβ6 in matrix metalloproteinase (MMP) expression and TGF-β1 activation, integrin αvβ6 is attractive as a tumor biomarker and potential therapeutic target.

The in vivo delivery of therapeutically effective compounds, such as drug compounds, to desired cells and/or tissues remains a challenge in drug product development. Currently, in the field of drug delivery, there is still a need for stable and effective targeting ligands that can selectively target cells or tissues, which can be used to promote the targeted delivery of transported molecules (e.g., therapeutically active compounds or ingredients) to specific cells or tissues. In fact, in the process of drug development, there is a general need for targeting ligands that can be conjugated to one or more selected transported molecules (e.g., one or more drug products or other payloads) to facilitate the delivery of the transported molecules to desired cells or tissues in vivo. In addition, there is a need for compounds that target integrin αvβ6, suitable for conjugation to transported molecules, to deliver the transported molecules to cells expressing integrin αvβ6 in vivo. For specific transported molecules, such as therapeutic oligonucleotide-based compounds (e.g., antisense oligonucleotides or RNAi agents), a targeting ligand capable of targeting integrin αvβ6 is needed, which can be conjugated to the oligonucleotide-based compound to deliver the therapeutic agent to cells and/or tissues expressing integrin αvβ6 and promote the entry of the therapeutic agent into the cell by receptor-mediated endocytosis, pinocytosis or other means.

Chinese patent CN201880070813.4 discloses an αvβ6 integrin ligand with serum stability The αvβ6 integrin ligand can be used to target cells expressing integrin αvβ6 in vitro, in situ, ex vivo and/or in vivo. It comprises the structure:

Chinese patent CN201980028704.0 discloses an integrin targeting ligand having serum stability and affinity for αvβ3 integrin and/or αvβ5 integrin, and suitable for conjugation to a transported molecule, such as an oligonucleotide-based therapeutic agent (e.g., an RNAi agent), to facilitate delivery of the transported molecule to cells and tissues, such as tumor cells, which express integrin αvβ3, integrin αvβ5, or both integrin αvβ3 and integrin αvβ5, comprising the structure:

At present, the research on integrin as targeting ligand is still very scarce. The development of new integrin ligands has important value and significance for drug delivery and disease treatment.

Summary of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a synthetic αvβ6 integrin ligand having good serum stability and affinity for integrin αvβ6, which can be specifically manifested as good targeting and inhibitory effects. The ligand can be used to deliver transported molecules such as RNAi agents or other oligonucleotide-based compounds to cells expressing integrin αvβ6, thereby promoting the uptake of the transported molecules into these cells, thereby achieving excellent pharmacodynamic activity.

The present invention provides a compound as shown in the following formula I, its tautomer or a pharmaceutically acceptable salt thereof, which is:

in,

Ring A is selected from optionally substituted C _3-10 cycloalkyl, 3-10 membered heterocycloalkyl and phenyl;

n is an integer from 0 to 7;

J is selected from C-H or N;

X is selected from -CH ₂ -, -C(=O)-;

Y is selected from -CH ₂ -, -C(=O)-;

Z is selected from OR ₆ , N(R ₆ ) ₂ or SR ₆ ;

R ₁ is selected from H, optionally substituted alkyl;

_R2 is selected from H, optionally substituted alkyl;

_R3 is selected from aryl optionally substituted by _R7 , optionally substituted heteroaryl, optionally substituted heterocyclyl, optionally substituted cycloalkyl, or _R3 comprises a transported molecule;

R ₄ is selected from H, C _1-3 alkyl;

R ₅ is selected from H, C _1-3 alkyl;

Each R ₆ is independently selected from H, optionally substituted alkyl, or R ₆ comprises a transported molecule;

wherein the substituents in ring A, R _1, R ₂ and R ₆ are independently selected from halogen, CF ₃ , OH, NH ₂ , C _1-6 alkoxy, and the number of substituents in each group is independently selected from 1, 2 or 3;

_R7 is selected from one or more divalent cyclic moieties having 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 carbon atoms optionally substituted by _R8 , wherein _R8 comprises one or more molecules to be transported.

In some embodiments of the present invention, the above n is 3, X is selected from -CH ₂ -, Y is selected from -CH ₂ -, and Z is selected from OH.

In some embodiments of the present invention, the above n is 3, X is selected from -C(=O)-, Y is selected from -C(=O)-, and Z is OH.

In some embodiments of the present invention, the above R ₁ is selected from _R2 is selected from H, _R3 is selected from phenyl, _R4 is selected from H, and _R5 is selected from H.

In some embodiments of the present invention, _R1 is selected from H, _R2 is selected from H, _R3 is selected from phenyl, _R4 is selected from H, and _R5 is selected from H.

In some embodiments of the present invention, R ₁ is selected from H, R ₂ is selected from H, R ₃ is selected from phenyl, R ₄ is selected from methyl, and R ₅ is selected from methyl.

In some embodiments of the present invention, the ring A is selected from

In some embodiments of the present invention, the above-mentioned J is selected from N.

In some embodiments of the present invention, the divalent cyclic moiety includes cycloalkyl, cycloalkenyl, aryl, heteroaryl The cycloalkyl group is cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or cycloheptyl, the cycloalkenyl group is cyclopentenyl, cyclobutenyl, cyclopentenyl, cyclohexenyl or cycloheptenyl, the aryl group is phenyl or naphthyl, the heteroaryl group is pyridyl, pyrimidinyl, pyridazinyl, pyrrole, pyrazole, imidazole, thiophene, benzothiophene, thiazole, benzothiazole, furan, oxazole, isoxazole, benzofuran, indole, indazole, benzimidazole, oxadiazole, 1,2,3-triazole, 1,2,4-triazole, tetrazole, quinolyl, isoquinolyl or quinoxalinyl, and the heterocyclic group is tetrahydrofuran, tetrahydropyran, piperidine, pyrrolidine, dioxane or dioxolane.

The present invention provides a compound of the following formula, a tautomer thereof or a pharmaceutically acceptable salt thereof,

wherein _R9 comprises a molecule to be transported (eg, an RNAi agent).

In some embodiments of the present invention, the above compound further comprises a polyethylene glycol linker having 2-20 ethylene oxide units. The polyethylene glycol linker having ethylene oxide units can be connected to the above compound and then connected to the transported molecule.

In another aspect, the present invention provides a compound of the following formula, a tautomer thereof or a pharmaceutically acceptable salt thereof, wherein the compound is selected from

in The point of attachment to the portion comprising the molecule being transported is indicated.

In another aspect, the present invention provides a compound of the following formula, a tautomer thereof or a pharmaceutically acceptable salt thereof, wherein the compound is selected from

in The point of attachment to the portion comprising the molecule being transported is indicated.

In some embodiments, the αvβ6 integrin ligand of structures I-1a, I-2a, I-3a, II-1a, II-2a, and II-3a is linked to one or more transported molecules (e.g., one or more RNAi agents).

In some embodiments of the present invention, the transported molecule is an active pharmaceutical ingredient or a prodrug.

In some embodiments of the present invention, the molecules transported include small molecules, antibodies, antibody fragments, immunoglobulins, monoclonal antibodies, markers or markers, lipids, natural or modified nucleic acids, natural or modified nucleic acid oligonucleotides, natural or modified nucleic acid polynucleotides, peptides, nucleic acid aptamers, polymers, polyamines, proteins, toxins, vitamins, polyethylene glycol, haptens, digoxin, biotin, radioactive atoms or molecules. subunit, or fluorophore.

In some embodiments of the present invention, the transported molecule comprises an RNAi agent.

In another aspect, the present invention provides a structure comprising a compound, a linker and a scaffold, wherein the structure is bound to a transported molecule, and the compound is an αvβ6 ligand. In some embodiments of the present invention, the structure comprises a monodentate form of an αvβ6 integrin ligand.

In some embodiments of the present invention, the above structure comprises a bidentate αvβ6 integrin ligand.

In some embodiments of the present invention, the above structure comprises a tridentate αvβ6 integrin ligand.

In some embodiments of the present invention, the above structure comprises a tetradentate form of the αvβ6 integrin ligand.

As disclosed herein, in some embodiments, one or more αvβ6 integrin ligands may be linked to one or more transported molecules. In some embodiments, only one αvβ6 integrin ligand is conjugated to the transported molecule (referred to herein as a "monodentate" or "monovalent" ligand). In some embodiments, two αvβ6 integrin ligands are conjugated to the transported molecule (referred to herein as a "bidentate" or "bivalent" ligand). In some embodiments, three αvβ6 integrin ligands are conjugated to the transported molecule (referred to herein as a "tridentate" or "trivalent" ligand). In some embodiments, four αvβ6 integrin ligands are conjugated to the transported molecule (referred to herein as a "tetradentate" or "tetravalent" ligand). In some embodiments, more than four αvβ6 integrin ligands are conjugated to the transported molecule.

In some embodiments, when only one αvβ6 integrin ligand is conjugated to the transported molecule (referred to herein as a "monodentate" ligand), the αvβ6 integrin ligand can be directly conjugated to the transported molecule. In some embodiments, the αvβ6 integrin ligand disclosed herein can be conjugated to the transported molecule via a scaffold or other linker structure.

In some embodiments, the αvβ6 integrin ligands disclosed herein include one or more scaffolds. Scaffolds, sometimes also referred to in the art as linkers or connectors, can be used to facilitate the connection of one or more transported molecules to one or more αvβ6 integrin ligands disclosed herein. Useful scaffolds compatible with the ligands disclosed herein are generally known in the art. Non-limiting examples of scaffolds that can be used with the αvβ6 integrin ligands disclosed herein include, but are not limited to, polymers and polyamino acids (e.g., diglutamic acid, poly-L-lysine, etc.). In some embodiments, the scaffold may include a cysteine linker or group, DBCO-PEG1-24-NHS, propargyl-PEG1-24-NHS and/or a multidentate DBCO and/or propargyl moiety. In some embodiments of the present invention, the above scaffold has the following formula:

in " represents the RNAi agent, and "αvβ6 ligand" represents the respective ligand structure and linker.

In some embodiments of the present invention, the αvβ6 integrin ligand disclosed in the present invention includes a tridentate structure of a glutaric acid linker and can be represented by the following structure:

In some embodiments of the present invention, the αvβ6 integrin ligand disclosed in the present invention includes a tridentate structure of a glutaric acid linker and can be represented by the following structure:

In some embodiments of the present invention, the αvβ6 integrin ligand disclosed in the present invention comprises a tridentate structure of a glutaric acid linker and can be represented by the following structure:

In some embodiments, the αvβ6 integrin ligand disclosed herein comprises a tridentate structure conjugated to a RNAi agent and can be represented by the following structure:

in represents RNAi agent, X＝O,S.

In some embodiments, the αvβ6 integrin ligand disclosed herein comprises a tridentate structure conjugated to a RNAi agent and can be represented by the following structure:

in represents RNAi agent, X＝O,S.

In some embodiments, the αvβ6 integrin ligand disclosed herein comprises a tridentate structure conjugated to a RNAi agent and can be represented by the following structure:

in represents RNAi agent, X＝O,S.

In some embodiments, the αvβ6 integrin ligand disclosed herein comprises a tridentate structure conjugated to a RNAi agent and can be represented by the following structure:

in represents RNAi agent, X＝O,S.

In some embodiments, the αvβ6 integrin ligand disclosed herein comprises a tridentate structure conjugated to a RNAi agent and can be represented by the following structure:

in represents RNAi agent, X＝O,S.

In another aspect, the present invention provides a compound as shown in the following formula Ib, a tautomer thereof or a pharmaceutically acceptable salt thereof, wherein the compound is an αvβ6 integrin ligand precursor comprising the structure:

in,

Ring A is selected from optionally substituted C _3-10 cycloalkyl, 3-10 membered heterocycloalkyl and phenyl;

n is an integer from 0 to 7;

J is selected from C-H or N;

X is selected from -CH ₂ -, -C(=O)-;

Y is selected from -CH ₂ -, -C(=O)-;

Z is selected from OR ₆ , N(R ₆ ) ₂ or SR ₆ ;

R ₁ is selected from H, optionally substituted alkyl;

_R2 is selected from H, optionally substituted alkyl;

_R3 is selected from aryl optionally substituted by _R7 , optionally substituted heteroaryl, optionally substituted heterocyclyl, optionally substituted cycloalkyl, or _R3 comprises a linker conjugated to a reactive group;

R ₄ is selected from H, C _1-3 alkyl;

R ₅ is selected from H, C _1-3 alkyl;

Each R ₆ is independently H, optionally substituted alkyl, or R ₆ comprises a linker group that is transported or conjugated to a reactive group;

wherein the substituents in ring A, R ₁ , R ₂ and R ₆ are independently selected from halogen, CF ₃ , OH, NH ₂ , C _1-6 alkoxy, and the number of substituents in each group is independently selected from 1, 2 or 3;

_R7 is selected from one or more divalent cyclic moieties having 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 carbon atoms optionally substituted with _R8 , wherein _R8 comprises a linking group conjugated to a reactive group.

In some embodiments of the present invention, the above n is 3, X is selected from -CH ₂ -, Y is selected from -CH ₂ -, and Z is selected from OH.

In some embodiments of the present invention, the above n is 3, X is selected from -C(=O)-, Y is selected from -C(=O)-, and Z is OH.

In some embodiments of the present invention, the above R ₁ is selected from _R2 is selected from H, _R3 is selected from phenyl, _R4 is selected from H, and _R5 is selected from H.

In some embodiments of the present invention, _R1 is selected from H, _R2 is selected from H, _R3 is selected from phenyl, _R4 is selected from H, and _R5 is selected from H.

In some embodiments of the present invention, R ₁ is selected from H, R ₂ is selected from H, R ₃ is selected from phenyl, R ₄ is selected from methyl, and R ₅ is selected from methyl.

In some embodiments of the present invention, the ring A is selected from

In some embodiments of the present invention, the above-mentioned J is selected from N.

In some embodiments of the present invention, the above-mentioned divalent cyclic portion includes cycloalkyl, cycloalkenyl, aryl, heteroaryl or heterocyclic group, the cycloalkyl is cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or cycloheptyl, the cycloalkenyl is cyclopentenyl, cyclobutenyl, cyclopentenyl, cyclohexenyl or cycloheptenyl, the aryl is phenyl or naphthyl, the heteroaryl is pyridyl, pyrimidinyl, pyridazinyl, pyrrole, pyrazole, imidazole, thiophene, benzothiophene, thiazole, benzothiazole, furan, oxazole, isoxazole, benzofuran, indole, indazole, benzimidazole, oxadiazole, 1,2,3-triazole, 1,2,4-triazole, tetrazole, quinolyl, isoquinolyl or quinoxalinyl, and the heterocyclic group is tetrahydrofuran, tetrahydropyran, piperidine, pyrrolidine, dioxane or dioxolane.

In some embodiments of the present invention, the above-mentioned linking group is a PEG linker.

In some embodiments of the present invention, the PEG linker comprises 2-20 PEG units.

In some embodiments of the present invention, the reactive group is an azide.

In some embodiments of the present invention, the linking group conjugated to the reactive group has the structure:

where m is an integer from 2 to 20, and represents the point of attachment to the structure of Formula Ib.

In another aspect, the present invention provides an αvβ6 integrin ligand precursor, a tautomer thereof or a pharmaceutically acceptable salt thereof, comprising a polyethylene glycol (PEG)-azide reactive group selected from:

In another aspect, the present invention provides an αvβ6 integrin ligand precursor, a tautomer thereof or a pharmaceutically acceptable salt thereof, comprising an azide reactive group selected from:

In another aspect, the present invention provides an αvβ6 integrin ligand precursor selected from:

or a pharmaceutically acceptable salt thereof.

In another aspect, the present invention provides an αvβ6 integrin ligand precursor selected from:

In another aspect, the present invention provides a composition comprising the above-mentioned compound or the above-mentioned structure. structure, and pharmaceutically acceptable excipients.

In some embodiments of the present invention, the above compounds are conjugated to oligonucleotide-based compounds capable of inhibiting the expression of target genes in epithelial cells.

In some embodiments of the present invention, the above-mentioned compound is conjugated with a RNAi agent capable of inhibiting the expression of a target gene in epithelial cells.

In some embodiments of the present invention, the above-mentioned compound is conjugated with a RNAi agent capable of inhibiting the expression of a target gene in bronchiolar epithelial cells.

In another aspect, the present invention provides a method of delivering one or more transported molecules to a cell, the method comprising administering to the cell the above-mentioned compound or the above-mentioned structure.

In another aspect, the present invention provides a method for delivering one or more transported molecules to a cell or tissue of a subject in vivo, the method comprising administering the above-mentioned compound, the above-mentioned structure or the above-mentioned composition to the subject.

In some embodiments of the present invention, the above-mentioned cells are selected from type I and type II alveolar epithelial cells, goblet cells, secretory epithelial cells, ciliated epithelial cells, corneal and conjunctival epithelial cells, dermal epithelial cells, bile duct epithelial cells, intestinal epithelial cells, ductal epithelial cells, glandular epithelial cells and epithelial tumor cancer.

In some embodiments of the invention, the one or more transported molecules comprise oligonucleotide-based compounds.

In some embodiments of the present invention, the above-mentioned oligonucleotide-based compound is a RNAi agent.

In another aspect, the present invention provides a method for inhibiting target gene expression in a cell in vivo, the method comprising administering to a subject an effective amount of a composition comprising an oligonucleotide-based compound conjugated to the above-mentioned compound.

In some embodiments of the present invention, the above-mentioned cells are selected from type I and type II alveolar epithelial cells, goblet cells, secretory epithelial cells, ciliated epithelial cells, corneal and conjunctival epithelial cells, dermal epithelial cells, bile duct epithelial cells, intestinal epithelial cells, ductal epithelial cells, glandular epithelial cells and epithelial tumors.

In some embodiments of the present invention, the above-mentioned oligonucleotide-based compound is a RNAi agent.

In some embodiments, the αvβ6 integrin ligands disclosed herein can be attached to one or more (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30; or 1 to 30, 1 to 25, 1 to 20, 1 to 15, 1 to 10, 1 to 5, 5 to 30, 5 to 25, 5 to 20, 5 to 15, 5 to 10, 10 to 30, 10 to 25, 10 to 20, 10 to 15, 15 to 30, 15 to 25, 15 to 20, 20 to 30, 20 to 25, or 25 to 30) conjugated to a transported molecule (e.g., any transported molecule described herein or known in the art).

In some embodiments, the αvβ6 integrin ligands disclosed herein are conjugated to one or more transported molecules, optionally via a linker group, such as, for example, a polyethylene glycol (PEG) group.

In another aspect, the present disclosure provides methods comprising using one or more αvβ6 integrin ligands and/or compositions as described herein, and, if desired, formulating the disclosed αvβ6 integrin ligands and/or compositions into a form suitable for administration as a pharmaceutical product. In other embodiments, the present disclosure provides methods for preparing the ligands and compositions described herein, e.g., medicaments.

Any of the αvβ6 integrin ligands disclosed herein can be linked to a transported molecule, a reactive group, and/or a protected reactive group. Reactive groups can be used to facilitate conjugation of the αvβ6 integrin ligand to the transported molecule. The αvβ6 integrin ligands disclosed herein can increase the targeting of the transported molecule to the αvβ6 integrin or to cells expressing the αvβ6 integrin. The transported molecule can be, but is not limited to, a pharmaceutically active ingredient or compound, a prodrug, or other substance with known therapeutic or diagnostic benefits. In some embodiments, the transported molecule can be, but is not limited to, a small molecule, an antibody, an antibody fragment, an immunoglobulin, a monoclonal antibody, a label or marker, a lipid, a natural or modified oligonucleotide-based compound (e.g., an antisense oligonucleotide or RNAi agent), a natural or modified nucleic acid, a peptide, a nucleic acid aptamer, a polymer, a polyamine, a protein, a toxin, a vitamin, a polyethylene glycol, a hapten, digoxin, biotin, a radioactive atom or molecule, or a fluorophore. In some embodiments, the transported molecule includes a pharmaceutically active ingredient or a prodrug. In some embodiments, the transported molecule includes an oligonucleotide-based compound as a pharmaceutically active ingredient. In some embodiments, the transported molecule includes a RNAi agent as a pharmaceutically active ingredient.

Reactive groups are well known in the art and provide the formation of a covalent bond between two molecules or reactants. Suitable reactive groups for the scope of the present invention include, but are not limited to, amino, amide, carboxylic acid, azide, alkyne, propargyl, BCN (bicyclo [6.1.0] nonyne, DBCO (dibenzocyclooctyne), thiol, maleimido, aminooxy, N-hydroxysuccinimide (NHS) or other activated esters (e.g., PNP, TFP, PFP), bromo, aldehyde, carbonate, tosylate, tetrazine, trans-cyclooctene (TCO), hydrazide, hydroxyl, disulfide and adjacent pyridyl disulfide groups.

The incorporation of reactive groups can facilitate the conjugation of the αvβ6 integrin ligands disclosed herein to the transported molecule. Conjugation reactions are well known in the art and provide for the formation of a covalent bond between two molecules or reactants. Suitable conjugation reactions for use within the scope of the present invention include, but are not limited to, amide coupling reactions, Michael addition reactions, hydrazone formation reactions, and click chemistry cycloaddition reactions.

Protected reactive groups are also commonly used in the art. Protecting groups provide conditions for the reaction of non-protecting groups. The invention relates to the temporary chemical conversion of a reactive group to a non-reactive group under certain conditions, for example, to provide chemical selectivity in a subsequent chemical reaction. Suitable protected reactive groups for use within the scope of the present invention include, but are not limited to, Boc groups (tert-butyloxycarbonyl), Fmoc (9-fluorenylmethoxycarbonyl), Cbz groups (carboxybenzyl), benzyl esters and Pbf (2,2,4,6,7-pentamethyldihydrobenzofuran-5-sulfonyl).

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. Provided is a synthetic αvβ6 integrin ligand of formula I, which has serum stability and affinity for integrin αvβ6, specifically manifested as a strong targeting effect. Integrin αvβ6 is a receptor expressed in a variety of cell types. The ligand can be used to deliver transported molecules such as RNAi agents or other oligonucleotide-based compounds to cells expressing integrin αvβ6, thereby promoting the uptake of the transported molecules into these cells, and manifested as excellent pharmacodynamic activity after binding to the RNAi agent.

2. Provided are a composition comprising an αvβ6 integrin ligand and a method of use.

3. Provided is a synthetic αvβ6 integrin ligand compound of formula I, which has a good αvβ6 integrin inhibitory effect and thus has an inhibitory effect on tumor growth.

4. Provided is a method for synthesizing the compound described in the present invention, which can be used for production and preparation.

Definition and description

Unless otherwise specified, the following terms and phrases used herein are intended to have the following meanings. A particular term or phrase should not be considered to be uncertain or unclear in the absence of a special definition, but should be understood according to its ordinary meaning. When a trade name appears in this article, it is intended to refer to its corresponding commercial product or its active ingredient.

The term "pharmaceutically acceptable" as used herein refers to those compounds, materials, compositions and/or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of humans and animals without excessive toxicity, irritation, allergic response or other problems or complications, commensurate with a reasonable benefit/risk ratio.

The term "pharmaceutically acceptable salt" refers to salts of the compounds of the present invention, prepared by reacting the compounds of the present invention with specific substituents with relatively non-toxic acids or bases. When the compounds of the present invention contain relatively acidic functional groups, base addition salts can be obtained by contacting the neutral form of such compounds with a sufficient amount of base in a pure solution or a suitable inert solvent. Pharmaceutically acceptable base addition salts include sodium, potassium, calcium, ammonium, organic amine or magnesium salts or similar salts. When the compounds of the present invention contain relatively basic functional groups, base addition salts can be obtained by contacting the neutral form of such compounds with a sufficient amount of acid in a pure solution or a suitable inert solvent. Acid addition salts are obtained by contacting with the amine. Examples of pharmaceutically acceptable acid addition salts include inorganic acid salts, such as hydrochloric acid, hydrobromic acid, nitric acid, carbonic acid, bicarbonate, phosphoric acid, monohydrogen phosphate, dihydrogen phosphate, sulfuric acid, hydrogen sulfate, hydroiodic acid, phosphorous acid, etc.; and organic acid salts, such as acetic acid, propionic acid, isobutyric acid, maleic acid, malonic acid, benzoic acid, succinic acid, suberic acid, fumaric acid, lactic acid, mandelic acid, phthalic acid, benzenesulfonic acid, p-toluenesulfonic acid, citric acid, tartaric acid and methanesulfonic acid, etc.; also include salts of amino acids (such as arginine, etc.), and salts of organic acids such as glucuronic acid. Certain specific compounds of the present invention contain basic and acidic functional groups, and can be converted into any base or acid addition salt.

Pharmaceutically acceptable salts of the present invention can be synthesized by conventional chemical methods from parent compounds containing acid radicals or bases. Generally, the preparation method of such salts is: in water or an organic solvent or a mixture of the two, these compounds in free acid or base form are reacted with a stoichiometric amount of an appropriate base or acid to prepare.

"Pharmaceutical composition" means containing one or more compounds described in the present application, their isomers or pharmaceutically acceptable salts thereof, and other components such as physiological/pharmaceutically acceptable carriers and excipients. The purpose of the pharmaceutical composition is to promote administration to an organism, facilitate the absorption of the active ingredient and thus exert biological activity. The pharmaceutical composition described herein may contain other additional components commonly found in pharmaceutical compositions. In some embodiments, the additional components are pharmaceutically active materials. Pharmaceutically active materials include, but are not limited to: antipruritic agents, astringents, local anesthetics or anti-inflammatory agents (e.g., antihistamines, diphenhydramine, etc.), small molecule drugs, antibodies, antibody fragments, nucleic acid aptamers and/or vaccines. The pharmaceutical composition may also contain preservatives, solubilizers, stabilizers, wetting agents, emulsifiers, sweeteners, colorants, odorants, salts for changing osmotic pressure, buffers, coating agents or antioxidants. They may also contain other agents with known therapeutic benefits.

Excipients include, but are not limited to, absorption enhancers, antiadherents, antifoaming agents, antioxidants, binders, buffers, carriers, coatings, colorants, delivery enhancers, delivery polymers, dextran, dextrose, diluents, disintegrants, emulsifiers, extenders, fillers, flavoring agents, glidants, humectants, lubricants, oils, polymers, preservatives, saline, salts, solvents, sugars, suspending agents, sustained release matrices, sweeteners, thickeners, tonicity agents, vehicles, hydrophobic agents, and wetting agents.

Unless otherwise stated, the term "isomer" is intended to include geometric isomers, cis-trans isomers, stereoisomers, enantiomers, optical isomers, diastereomers and tautomers.

The compounds of the present invention may exist in specific geometric or stereoisomeric forms. The present invention contemplates all such compounds, including cis and trans isomers, (-)- and (+)-enantiomers, (R)- and (S)-enantiomers, non-enantiomers, The present invention also includes the following: enantiomers, (D)-isomers, (L)-isomers, and racemic mixtures and other mixtures thereof, such as mixtures enriched in enantiomers or diastereomers, all of which are within the scope of the present invention. Additional asymmetric carbon atoms may be present in substituents such as alkyl. All of these isomers and their mixtures are included within the scope of the present invention.

Unless otherwise indicated, the term "enantiomer" or "optical isomer" refers to stereoisomers that are mirror images of one another.

Unless otherwise indicated, the term "cis-trans isomers" or "geometric isomers" arises from the inability of a ring carbon atom to rotate freely about double bonds or single bonds forming a ring.

Unless otherwise indicated, the term "diastereomer" refers to stereoisomers that have two or more chiral centers and that are not mirror images of each other.

Unless otherwise indicated, "(+)" indicates dextrorotatory, "(-)" indicates levorotatory, and "(±)" indicates racemic.

Unless otherwise specified, the key is a solid wedge. and dotted wedge key To indicate the absolute configuration of a stereocenter, use a straight solid bond. and straight dashed key To indicate the relative configuration of a stereocenter, use a wavy line Indicates a wedge-shaped solid key or dotted wedge key Or use a wavy line Represents a straight solid bond or straight dashed key

Unless otherwise indicated, the terms "enriched in one isomer", "isomerically enriched", "enriched in one enantiomer" or "enantiomerically enriched" mean that the content of one isomer or enantiomer is less than 100%, and the content of the isomer or enantiomer is greater than or equal to 60%, or greater than or equal to 70%, or greater than or equal to 80%, or greater than or equal to 90%, or greater than or equal to 95%, or greater than or equal to 96%, or greater than or equal to 97%, or greater than or equal to 98%, or greater than or equal to 99%, or greater than or equal to 99.5%, or greater than or equal to 99.6%, or greater than or equal to 99.7%, or greater than or equal to 99.8%, or greater than or equal to 99.9%.

Unless otherwise indicated, the term "isomer excess" or "enantiomeric excess" refers to the difference between the relative percentages of two isomers or two enantiomers. For example, if the content of one isomer or enantiomer is 90% and the content of the other isomer or enantiomer is 10%, the isomer or enantiomeric excess (ee value) is 80%.

Optically active (R)- and (S)-isomers as well as D and L isomers can be prepared by chiral synthesis or chiral reagents or other conventional techniques. If one enantiomer of a compound of the present invention is desired, it can be prepared by asymmetric synthesis or derivatization with a chiral auxiliary, wherein the resulting diastereomeric mixture is separated and the auxiliary group is cleaved to provide the pure desired enantiomer. Alternatively, when the molecule contains a basic functional group (such as an amino group) or an acidic functional group (such as a carboxyl group), a diastereomeric salt is formed with an appropriate optically active acid or base, and then the diastereoisomers are separated by conventional methods known in the art. The pure enantiomer is then recovered.Alternatively, separation of enantiomers and diastereomers is often accomplished by the use of chromatography employing a chiral stationary phase, optionally coupled with chemical derivatization (eg, formation of carbamates from amines).

The compounds of the present invention may contain non-natural proportions of atomic isotopes on one or more atoms constituting the compound. For example, the compound may be labeled with a radioactive isotope, such as tritium (3H), iodine-125 (125I) or C-14 (14C). For another example, deuterated drugs may be formed by replacing hydrogen with heavy hydrogen. The bond between deuterium and carbon is stronger than the bond between ordinary hydrogen and carbon. Compared with undeuterated drugs, deuterated drugs have the advantages of reducing toxic side effects, increasing drug stability, enhancing therapeutic effects, and extending the biological half-life of drugs. All isotopic composition changes of the compounds of the present invention, whether radioactive or not, are included in the scope of the present invention.

The terms "optional" or "optionally" mean that the subsequently described event or circumstance may but need not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

The term "substituted" means that any one or more hydrogen atoms on a particular atom are replaced by a substituent, which may include a variant of deuterium and hydrogen, as long as the valence state of the particular atom is normal and the substituted compound is stable. When the substituent is oxygen (i.e., =O), it means that two hydrogen atoms are replaced. Oxygen substitution does not occur on aromatic groups. The term "optionally substituted" means that it may be substituted or not substituted, and unless otherwise specified, the type and number of the substituents may be arbitrary on the basis of chemical achievable.

When any variable (e.g., R) occurs more than once in a compound's composition or structure, its definition at each occurrence is independent. Thus, for example, if a group is substituted with 0-2 Rs, the group may be optionally substituted with up to two Rs, and each occurrence of R is an independent choice. In addition, combinations of substituents and/or variants thereof are permitted only if such combinations result in stable compounds.

When the number of a linking group is 0, such as -(CRR) ₀ -, it means that the linking group is a single bond.

When the number of a substituent is 0, it means that the substituent does not exist, for example, -A-(R) ₀ means that the structure is actually -A.

When a substituent is vacant, it means that the substituent does not exist. For example, when X in A-X is vacant, it means that the structure is actually A.

When one of the variables is selected from a single bond, it means that the two groups it connects are directly connected. For example, when L in A-L-Z represents a single bond, it means that the structure is actually A-Z.

When a substituent has bonds that cross two or more atoms in a ring, can be bonded to any atom on this ring, e.g. Indicates that the substituent R can be substituted at any position on the cyclohexyl group or cyclohexadiene. When the listed substituents do not specify which atom is connected to the substituted group, the substituent can be bonded through any atom thereof. For example, a pyridyl substituent can be connected to the substituted group through any carbon atom on the pyridine ring.

When the listed linking group does not indicate its linking direction, its linking direction is arbitrary, for example, The connecting group L is -MW-, in which case -MW- can connect ring A and ring A in the same direction as the reading order from left to right to form It is also possible to connect ring A and ring A in the opposite direction of the reading order from left to right to form Combinations of linkers, substituents, and/or variations thereof are permissible only if such combinations result in stable compounds.

A linker or connecting group is a connection between two atoms that connects a chemical group (such as an RNAi agent) or a fragment of interest to another chemical group (such as an αvβ6 ligand, a pharmacokinetic modulator, or a delivery polymer) or a fragment of interest via one or more covalent bonds. An unstable connection contains an unstable bond. The connection may optionally include a spacer group that increases the distance between the two connected atoms. The spacer group may further increase the flexibility and/or length of the connection. Spacer groups include, but are not limited to, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, aralkyl groups, aralkenyl groups, and aralkynyl groups; each of which may contain one or more heteroatoms, heterocycles, amino acids, nucleotides, and sugars. Spacer groups are well known in the art, and the foregoing list is not meant to limit the scope of this specification.

In some embodiments, the αvβ6 ligand is linked to the transported molecule without the use of an additional linker. In some embodiments, the αvβ6 ligand is designed with a readily available linker to facilitate linkage to the transported molecule. In some embodiments, when two or more RNAi agents are included in the composition, the two or more RNAi agents can be linked to their respective targeting groups using the same linker. In some embodiments, when two or more RNAi agents are included in the composition, different linkers are used to link the two or more RNAi agents to their respective targeting groups.

Unless otherwise specified, when a group has one or more connectable sites, any one or more sites of the group can be connected to other groups through chemical bonds. When the chemical bond connection mode is non-positional and there are H atoms at the connectable sites, when the chemical bonds are connected, the number of H atoms at the site will decrease with the number of connected chemical bonds to become a group with the corresponding valence. The chemical bond connecting the site to other groups can be a straight solid bond. Straight dotted key or wavy line For example, the straight solid bond in -OCH ₃ indicates that it is connected to other groups through the oxygen atom in the group; The straight dashed bond in the group indicates that the two ends of the nitrogen atom in the group are connected to other groups; The wavy lines in the phenyl group represent the connection to other groups through the carbon atoms at positions 1 and 2 in the phenyl group.

Unless otherwise specified, "halo" or "halogen" refers to fluorine, chlorine, bromine, and iodine; "halo" refers to monohalo or polyhalo, such as "haloalkane" refers to monohaloalkyl or polyhaloalkyl, and the polyhalo may be the same halogen atom or different halogen atoms; specifically, halomethyl includes but is not limited to chloromethyl, dichloromethyl, trifluoromethyl, etc.

"Alkoxy" represents an alkyl group with a specific number of carbon atoms connected by an oxygen bridge. Unless otherwise specified, C1-6 alkoxy includes C1, C2, C3, C4, C5 and C6 alkoxy. Examples of alkoxy include, but are not limited to, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, n-pentoxy and S-pentoxy.

Unless otherwise specified, the term "aryl" refers to a polyunsaturated aromatic hydrocarbon substituent, which may be monosubstituted or polysubstituted, monovalent, divalent or polyvalent, and which may be monocyclic or polycyclic (e.g., 1 to 3 rings; at least one of which is aromatic), fused together or covalently linked. The term "heteroaryl" refers to an aryl group (or ring) containing one to four heteroatoms. In an exemplary embodiment, the heteroatoms are selected from B, N, O and S, wherein the nitrogen and sulfur atoms are optionally oxidized and the nitrogen atom is optionally quaternized. The heteroaryl group may be attached to the rest of the molecule via a heteroatom. Non-limiting examples of aryl or heteroaryl groups include phenyl, naphthyl, biphenyl, pyrrolyl, pyrazolyl, imidazolyl, pyrazinyl, oxazolyl, phenyl-oxazolyl, isoxazolyl, thiazolyl, furanyl, thienyl, pyridyl, pyrimidinyl, benzothiazolyl, purinyl, benzimidazolyl, indolyl, isoquinolyl, quinoxalinyl, quinolyl, 1-naphthyl, 2-naphthyl, 4-biphenyl, 1-naphthyl, 2-naphthyl, 4-biphenyl, 1- -pyrrolyl, 2-pyrrolyl, 3-pyrrolyl, 3-pyrazolyl, 2-imidazolyl, 4-imidazolyl, pyrazinyl, 2-oxazolyl, 4-oxazolyl, 2-phenyl-4-oxazolyl, 5-oxazolyl, 3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl, 2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 2-furyl, 3-furyl, 2-thienyl, 3-thienyl yl, 2-pyridyl, 3-pyridyl, 4-pyridyl, 2-pyrimidinyl, 4-pyrimidinyl, 5-benzothiazolyl, purinyl, 2-benzimidazolyl, 5-indolyl, 1-isoquinolyl, 5-isoquinolyl, 2-quinoxalinyl, 5-quinoxalinyl, 3-quinolyl and 6-quinolyl.

The term "leaving group" refers to a functional group or atom that can be replaced by another functional group or atom through a substitution reaction (e.g., an affinity substitution reaction). For example, representative leaving groups include trifluoromethanesulfonate; chlorine, bromine, iodine; sulfonate groups, such as mesylate, tosylate, p-brosylate, p-toluenesulfonate, etc.; acyloxy groups, such as acetoxy, trifluoroacetoxy, etc.

The term "protecting group" includes, but is not limited to, "amino protecting group", "hydroxy protecting group" or "thiol protecting group". The term "amino protecting group" refers to a protecting group suitable for preventing side reactions at the amino nitrogen position. Representative amino protecting groups include, but are not limited to: formyl; acyl, such as alkanoyl (such as acetyl, trichloroacetyl or trifluoroacetyl); alkoxycarbonyl, such as tert-butyloxycarbonyl (Boc); arylmethoxycarbonyl, such as benzyloxycarbonyl (Cbz) and 9-fluorenylmethoxycarbonyl (Fmoc); arylmethyl, such as benzyl (Bn), trityl (Tr), 1,1-bis-(4'-methoxyphenyl)methyl; silyl, such as trimethylsilyl (TMS) and tert-butyldimethylsilyl (TBS), etc. The term "hydroxy protecting group" refers to a protecting group suitable for preventing side reactions of the hydroxyl group. Representative hydroxy protecting groups include, but are not limited to, alkyl groups such as methyl, ethyl and tert-butyl; acyl groups such as alkanoyl (e.g., acetyl); arylmethyl groups such as benzyl (Bn), p-methoxybenzyl (PMB), 3,4-dimethoxybenzyl (3,4-DMPM); silyl groups such as trimethylsilyl (TMS) and tert-butyldimethylsilyl (TBS), and the like.

Unless otherwise specified, Cn _-n+m alkyl or _Cn - _Cn+m alkyl includes saturated hydrocarbon groups of any specific situation of n to n+m carbon atoms, for example, _C1-12 alkyl includes _C1 , _C2 , C3, C4, _{C5 , C6} , _C7 , C8, _C9 , _C10 , _C11 , and _C12 alkyl, and also includes any range from n to n+m, for example, _C1-12 alkyl includes _C1-3 , _{C1-6 , C1-9} , _C3-6 , _C3-9 , _C3-12 , _C6-9 , _C6-12 , and _C9-12 alkyl _; it can be monovalent (such as methyl), divalent (such as methylene) or polyvalent (such as methine), for example, C Examples of _1-4 alkyl include, but are not limited to, methyl (Me), ethyl (Et), propyl (including n-propyl and isopropyl), butyl (including n-butyl, isobutyl, s-butyl and t-butyl), and the like.

Unless otherwise specified, "alkenyl" refers to an alkyl group having one or more carbon-carbon double bonds at any position of the chain, which may be monosubstituted or polysubstituted and may be monovalent, divalent or polyvalent. Examples of alkenyl groups include ethenyl, propenyl, butenyl, pentenyl, hexenyl, butadienyl, pentadienyl, hexadienyl, etc.

Unless otherwise specified, "alkynyl" refers to an alkyl group having one or more carbon-carbon triple bonds at any position of the chain, which may be mono- or poly-substituted and may be mono-, di- or polyvalent. Examples of alkynyl groups include ethynyl, Propynyl, butynyl, pentynyl, etc.

Unless otherwise specified, the number of atoms in the ring is generally defined as the number of ring members, for example, "5-7 membered ring" refers to a "ring" with 5-7 atoms arranged around; "C _3-n cycloalkyl" refers to a saturated cyclic hydrocarbon group consisting of 3 to n carbon atoms, including monocyclic, bicyclic and tricyclic systems, wherein the bicyclic and tricyclic systems include spirocyclic, cyclic and bridged rings, for example, "C _3-10 cycloalkyl" refers to a saturated cyclic hydrocarbon group consisting of 3 to 10 carbon atoms, including monocyclic, bicyclic and tricyclic systems, wherein the bicyclic and tricyclic systems include spirocyclic, cyclic and bridged rings. The C _3-10 cycloalkyl includes cycloalkyl groups of C _3-8 , C _3-6 , C _3-5 , C _4-10 , C _4-8 , C _4-6 , C _4-5 , C _5-8 or C _5-6, etc.; it can be monovalent, divalent or polyvalent. Examples of C _3-10 cycloalkyl include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, norbornyl, [2.2.2]bicyclooctane, [4.4.0]bicyclodecane and the like.

Unless otherwise specified, cycloalkenyl includes any stable cyclic or polycyclic hydrocarbon radical, which contains one or more unsaturated carbon-carbon double bonds at any position of the ring, which may be monosubstituted or polysubstituted, and may be monovalent, divalent or polyvalent. Examples of these cycloalkenyl radicals include, but are not limited to, cyclopentenyl, cyclohexenyl, etc.

Unless otherwise specified, cycloalkynyl includes any stable cyclic or polycyclic hydrocarbon radical containing one or more carbon-carbon triple bonds at any position of the ring, which may be mono- or poly-substituted and may be mono-, di- or polyvalent.

Unless otherwise specified, the term "3-n-membered heterocycloalkyl" by itself or in combination with other terms refers to a saturated cyclic group consisting of 3 to n ring atoms, wherein the heteroatoms of the heterocycloalkyl group are heteroatoms independently selected from O, S, N, P and Se, and the rest are carbon atoms, wherein the nitrogen atom is optionally quaternized, and the nitrogen, sulfur and phosphorus heteroatoms may be optionally oxidized (i.e., NO, S(O) _p and P(O) _p , p is 1 or 2). It includes monocyclic, bicyclic and tricyclic ring systems, wherein the bicyclic and tricyclic ring systems include spirocyclic, fused and bridged rings. For example, "3-10-membered heterocycloalkyl" by itself or in combination with other terms refers to a saturated cyclic group consisting of 3 to 10 ring atoms, wherein the heteroatoms are heteroatoms independently selected from O, S, N, P and Se, and the rest are carbon atoms, wherein the nitrogen atom is optionally quaternized, and the nitrogen, sulfur and phosphorus heteroatoms may be optionally oxidized (i.e., NO, S(O) _p and P(O) _p , p is 1 or 2). It includes monocyclic, bicyclic and tricyclic systems, wherein the bicyclic and tricyclic systems include spirocyclic, fused and bridged rings, and the “3-10 membered heterocycloalkyl” also includes 3-9 membered, 3-8 membered, 3-6 membered, 5-9 membered, 5 membered, 6 membered, 7 membered, 8 membered and 9 membered heterocycloalkyl, etc. Specifically, the “3-10 membered heterocycloalkyl” may include but is not limited to azetidinyl, oxetanyl, thiidine, pyrrolidinyl, pyrazolidinyl, imidazolidinyl, tetrahydrothiophenyl (including tetrahydrothiophen-2-yl and tetrahydrothiophen-3-yl, etc.), tetrahydrofuranyl (including tetrahydrofuran-2-yl, etc.), tetrahydropyranyl, piperidinyl (including 1-piperidinyl, 2-piperidinyl and 3-piperidinyl, etc.), piperidinyl oxazinyl (including 1-piperazinyl and 2-piperazinyl, etc.), morpholinyl (including 3-morpholinyl and 4-morpholinyl, etc.), dioxanyl, dithianyl, isoxazolidinyl, isothiazolidinyl, 1,2-oxazinyl, 1,2-thiazinyl, hexahydropyridazinyl, homopiperazinyl, homopiperidinyl or dioxepanyl, etc.

"Compounds based on oligonucleotides" include, but are not limited to, single-stranded oligonucleotides, single-stranded antisense oligonucleotides, short interfering RNA (siRNA), double-stranded RNA (dsRNA), microRNA (miRNA), short hairpin RNA (shRNA), ribozymes, interfering RNA molecules, and dicer substrates. In some embodiments, the compound based on oligonucleotides is a single-stranded oligonucleotide, such as an antisense oligonucleotide. In some embodiments, the compound based on oligonucleotides is a double-stranded oligonucleotide. In some embodiments, the compound based on oligonucleotides is a double-stranded oligonucleotide, which is an RNAi agent.

In some embodiments, one or more transported molecules are "RNAi agents", which are compositions containing RNA or RNA-like (e.g., chemically modified RNA) oligonucleotide molecules as defined herein, which can degrade or inhibit the translation of messenger RNA (mRNA) transcripts of target mRNA in a sequence-specific manner. As used herein, RNAi agents can act by RNA interference mechanisms (i.e., by inducing RNA interference by interacting with RNA interference pathway mechanisms (RNA-induced silencing complexes or RISC) of mammalian cells) or by any one or more alternative mechanisms or pathways. Although it is believed that RNAi agents, as the term used herein, act primarily by RNA interference mechanisms, the disclosed RNAi agents are not bound or limited by any particular pathway or mechanism of action. The RNAi agents disclosed herein are composed of sense strands and antisense strands, and include but are not limited to: short (or small) interfering RNA (siRNA), double-stranded RNA (dsRNA), microRNA (miRNA), short hairpin RNA (shRNA) and dicer substrates. The antisense strand of the RNAi agent described herein is at least partially complementary to the targeted mRNA. The RNAi agent can include one or more modified nucleotides and/or one or more non-phosphodiester bonds.

Oligonucleotide-based compounds, particularly RNAi agents, can generally be composed of modified nucleotides and/or one or more non-phosphodiester bonds. As used herein, "modified nucleotides" are nucleotides other than ribonucleotides (2'-hydroxy nucleotides). In some embodiments, at least 50% (e.g., at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 97%, at least 98%, at least 99% or 100%) of the nucleotides are modified nucleotides. As used herein, modified nucleotides include, but are not limited to, deoxyribonucleotides, nucleotide mimetics, abasic nucleotides, 2'-modified nucleotides, 3' to 3' linkage (inverted) nucleotides, nucleotides containing non-natural bases, bridged nucleotides, peptide nucleic acids, 2', 3'-acyclic nucleotide mimetics (unlocked nucleobase analogs), locked nucleotides, 3'-O-methoxy (2' internucleoside linked) nucleotides, 2'-F-arabino nucleotides, 5'-Me, 2'-fluoro nucleotides, morpholino nucleotides, vinylphosphonate deoxyribonucleotides, Nucleotides, vinylphosphonate-containing nucleotides and cyclopropylphosphonate-containing nucleotides. 2'-modified nucleotides (i.e., nucleotides having a group other than a hydroxyl group at the 2' position of the five-membered sugar ring) include, but are not limited to, 2'-O-methyl nucleotides, 2'-deoxy-2'-fluoro nucleotides, 2'-deoxy nucleotides, 2'-methoxyethyl (2'-O-2-methoxyethyl) nucleotides, 2'-amino nucleotides and 2'-alkyl nucleotides.

In addition, one or more nucleotides of an oligonucleotide-based compound (such as an RNAi agent) can be linked by a non-standard bond or backbone (i.e., a modified internucleoside bond or a modified backbone). The modified internucleoside linkage can be a non-phosphate-containing covalent internucleoside bond. Modified internucleoside linkages or backbones include, but are not limited to, 5'-phosphorothioate groups, chiral phosphorothioates, phosphorothioates, phosphorodithioates, phosphotriesters, aminoalkyl-phosphotriesters, alkyl phosphonates (e.g., methylphosphonates or 3'-alkylenephosphonates), chiral phosphonates, phosphinates, phosphoramidates (e.g., 3'-aminophosphoramidates, aminoalkylphosphoramidates, or thiophosphoramidates), thioalkyl-phosphonates, thioalkylphosphotriesters, morpholino linkages, boranophosphates with normal 3'-5' linkages, 2'-5' linked analogs of boranophosphates, or boranophosphates with reverse polarity where adjacent pairs of nucleoside units are linked 3'-5' to 5'-3' or 2'-5' to 5'-2'.

All positions in a given compound need not be uniformly modified. Instead, more than one modification may be incorporated into a single oligonucleotide-based compound or even a single nucleotide thereof.

The αvβ6 integrin ligand includes its salt or solvate. The solvate of the αvβ6 integrin ligand means the addition of inert solvent molecules to the αvβ6 integrin ligand, which is formed due to their mutual attraction. The solvate is, for example, a mono- or dihydrate or an addition compound with an alcohol, such as, for example, an addition compound with methanol or ethanol.

A free amino group or a free hydroxyl group can be provided as a substituent of the αvβ6 integrin ligand together with a corresponding protective group. The αvβ6 integrin ligand also includes, for example, a derivative, i.e., an αvβ6 integrin ligand modified with, for example, an alkyl or acyl group, a sugar or an oligopeptide, which is cleaved in vitro or in an organism.

In some embodiments, the αvβ6 integrin ligands disclosed herein facilitate delivery of transported molecules to the cytoplasm of cells that present the αvβ6 integrin on their surface by ligand-mediated endocytosis, pinocytosis, or by other means. In some embodiments, the αvβ6 integrin ligands disclosed herein facilitate delivery of transported molecules to the plasma membrane of cells that present the αvβ6 integrin.

The compounds of the present invention can be prepared by a variety of synthetic methods well known to those skilled in the art, including the specific embodiments listed below, embodiments formed by combining them with other chemical synthesis methods, and equivalent substitutions well known to those skilled in the art. Preferred embodiments include but are not limited to the embodiments of the present invention.

The structure of the compound of the present invention can be confirmed by conventional methods known to those skilled in the art. If the present invention relates to the absolute configuration of the compound, the absolute configuration can be confirmed by conventional technical means in the art. For example, single crystal X-ray diffraction (SXRD) is used to collect diffraction intensity data of the cultured single crystal using a Bruker D8 venture diffractometer, the light source is CuKα radiation, and the scanning mode is: After scanning and collecting relevant data, the crystal structure is further analyzed using the direct method (Shelxs97) to confirm the absolute configuration.

The solvent used in the present invention is commercially available.

The present invention uses the following abbreviations:

Compounds are named according to the conventional nomenclature in the art or using The software names were used, and commercially available compounds were named using the supplier's catalog names.

DETAILED DESCRIPTION

The present invention is further described in detail below with reference to embodiments and drawings, but the embodiments of the present invention are not limited thereto.

Example 1: 3-Cyclopropyl-3-(3-((1-(2-((4-(dodecyloxy)phenyl)(neopentyl)carbamoyl)-5-methoxyphenyl)piperidin-4-yl)methoxy)phenyl)propanoic acid (1)

Synthesis route:

Step 1: (S)-3-(4-bromophenyl)-3-((tert-butoxycarbonyl)amino)propanoic acid methyl ester (1-6-2)

In a clean 250mL single-necked flask, add (S)-3-(4-bromophenyl)-3-((tert-butoxycarbonyl)amino)propionic acid (5g, 14.53mmol), DMF (25mL), potassium carbonate (3.01g, 21.80mmol), stir for 15 minutes, then drop iodomethane (3.71g, 26.15mmol), and continue the reaction at room temperature. Post-treatment: add water (100mL), extract with ethyl acetate (30mL×2), wash the organic phase with saturated brine (30mL×4), dry with anhydrous sodium sulfate, filter, and purify by column chromatography (PE/EA(V/V)＝4/1) to obtain the title compound as a white solid (5.14g, 98.85%).

MS:(ESI,pos.ion)m/z：380.0454[M+Na] ⁺

Step 2: (S)-3-amino-3-(4-bromophenyl)propionic acid methyl ester hydrochloride (1-6-3)

In a clean 100mL single-necked flask, add (S)-3-(4-bromophenyl)-3-((tert-butoxycarbonyl)amino)propionic acid methyl ester (5.14g, 14.35mmol) and 4N hydrogen chloride dioxane solution (35.88mL, 143.5mmol), and stir at room temperature for reaction. Post-treatment: Concentrate under reduced pressure to constant weight to obtain a white solid (4.23g, 100%).

MS:(ESI,pos.ion)m/z：258.015[M+H] ⁺

Step 3: (S)-methyl 3-(4-bromophenyl)-3-(2-((tert-butoxycarbonyl)amino)acetylamino)propanoate (1-6-4)

In a clean 250mL single-necked flask, add (tert-butyloxycarbonyl)glycine (3.77g, 21.52mmol), DMF (64mL), HATU (10.575g, 28.7mmol), stir at room temperature for 0.5h, then add (S)-3-amino-3-(4-bromophenyl)propionic acid methyl ester hydrochloride (4.23g, 14.53mmol) at 0℃, and drop DIPEA (9.31g, 71.75mmol). After the drop is complete, move to room temperature for reaction. Post-treatment: add water (200mL), extract with ethyl acetate (60mL×2), combine the organic phases, wash the organic phases with saturated brine (60mL×4), dry over anhydrous sodium sulfate, filter, concentrate, and purify by column chromatography (DCM/MeOH (V/V)＝20/1) to obtain the title compound as a red oil. Product (6.5g, based on 100%).

MS:(ESI,pos.ion)m/z：359.0273[M-56+H] ⁺

Step 4: (S)-methyl 3-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)-3-(2-(((tert-butoxycarbonyl)amino)acetamido)propanoate (1-6-5)

In a 100 mL double-necked flask, (S)-methyl 3-(4-bromophenyl)-3-(2-((tert-butoxycarbonyl)amino)acetylamino)propanoate (1.25 g, 3.01 mmol), 2-(4-(benzyloxy)naphthalen-1-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1.63 g, 4.51 mmol), tetrahydrofuran (33 mL), water (8.34 mL), potassium phosphate (1.28 g, 6.02 mmol) and XPhos Pd G2 (118.26 mg, 0.15 mmol) were added. The atmosphere was replaced with nitrogen and protected. The reaction was stirred at room temperature for 8 hours. Post-treatment: ethyl acetate (40 mL) and saturated brine (40 mL) were added for separation, the aqueous phase was extracted with ethyl acetate (30 mL × 3), the organic phases were combined, washed with saturated brine (30 mL × 2), dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure and purified by column chromatography (PE/EA (V/V) = 10/1) to give the title compound as a colorless oil (1.25 g, 73.03%).

MS:(ESI,pos.ion)m/z：513.2037[M-56+H] ⁺

Step 5: (S)-3-(2-aminoacetylamino)-3-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)propanoic acid methyl ester hydrochloride (1-6)

In a 50 mL single-mouth bottle, add (S)-3-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)-3-(2-(((tert-butoxycarbonyl)amino)acetamido)propanoic acid methyl ester (0.4 g, 0.703 mmol), cool to 0°C, add 4N hydrogen chloride dioxane solution (1.75 g, 14.07 mmol), and stir at room temperature for 8 hours. Post-treatment: The reaction solution was directly spin-dried and used in the next step to obtain the title compound as a colorless oil (270 mg, 81.90%).

MS:(ESI,pos.ion)m/z：469.20[M+H] ⁺

Step 6: Ethyl 4-(1,8-naphthyridin-2-yl)butyrate (1-2)

Add 2-aminonicotinaldehyde (10 g, 81.88 mmol), ethyl 5-oxohexanoate (25.91 g, 163.76 mmol), L-proline (2.36 g, 20.47 mmol), and ethanol (100 mL) to a clean 500 mL single-necked flask and stir at 80°C to react. Post-treatment: cool to room temperature and purify by column chromatography (PE/EA (V/V) = 2/1) to obtain the title compound as a yellow oil (11.90 g, 59.50%)

MS:(ESI,pos.ion)m/z：245.1388[M+H] ⁺

Step 7: Ethyl 4-(5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)butanoate (1-3)

In a clean 500mL single-necked flask, add 4-(1,8-naphthyridin-2-yl)butyric acid ethyl ester (11.90g, 48.71mmol) and ethyl acetate (239mL), 10% Pd/C (1.19g), evacuate, replace hydrogen three times, and react at room temperature under hydrogen atmosphere. Post-treatment: filtration, column chromatography purification (DCM/MeOH (V/V) = 20/1) to obtain the standard The title compound was a yellow oil (11.66 g, 96.36%).

MS:(ESI,pos.ion)m/z：249.1786[M+H] ⁺

Step 8: tert-Butyl 7-(4-ethoxy-4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (1-4)

In a clean 500mL three-necked flask, add 4-(5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)butyric acid ethyl ester (10g, 40.27mmol), Boc anhydride (26.37g, 120.81mmol) and tetrahydrofuran (100mL), place at 0℃ and under nitrogen protection, drop 1N LiHMDS tetrahydrofuran solution (60.405mL, 60.405mmol), after the drop is complete, move to room temperature for reaction. Post-treatment: add 200mL of water, extract with ethyl acetate (100mL×2), combine the organic phases, dry over anhydrous sodium sulfate, filter, concentrate the filtrate under reduced pressure, and purify by column chromatography (PE/EA(V/V)＝4/1) to obtain the title compound as a colorless oil (11.88g, 84.68%).

MS:(ESI,pos.ion)m/z：349.2241[M+H] ⁺

Step 9: 4-(8-(tert-Butoxycarbonyl)-5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)butanoic acid (1-5)

In a clean 250mL single-necked flask, add tert-butyl 7-(4-ethoxy-4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (6.0g, 17.24mmol), THF (24mL), MeOH (24mL) and water (24mL), add LiOH (0.7g, 29.31mmol) at 0℃, and move to room temperature for reaction. Post-treatment: adjust pH to 5-6 with 6% citric acid, extract with dichloromethane (60mL×2), combine the organic phases, dry over anhydrous sodium sulfate, filter, concentrate the filtrate under reduced pressure, and purify by column chromatography (DCM/MeOH (V/V)＝20/1) to obtain the title compound as a light yellow oil (2.90g, 52.54%).

MS:(ESI,pos.ion)m/z：321.1908[M+H] ⁺

Step 10: (S)-7-(4-((2-((1-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)-3-methoxy-3-oxopropyl)amino)-2-oxoethyl)amino)-4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylic acid tert-butyl ester (1-7)

In a clean 100 mL single-necked flask, add 4-(8-(tert-butoxycarbonyl)-5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)butanoic acid (0.928 g, 2.81 mmol), DMF (20 mL), HATU (2.0 g, 5.27 mmol), stir at room temperature for 0.5 h, then add (S)-3-(2-aminoacetylamino)-3-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)propanoic acid methyl ester hydrochloride (1.33 g, 2.63 mmol) at 0 °C, add DIPEA (1.70 g, 13.17 mmol) dropwise, and after completion of the dropwise addition, move to room temperature for reaction. Post-treatment: add water (100 mL), extract with ethyl acetate (30 mL×2), combine the organic phases, wash with saturated brine (30 mL×4), dry over anhydrous sodium sulfate, filter, concentrate, and purify by column chromatography (DCM/MeOH (V/V)＝40/1) to obtain the title compound as a yellow oil (1.24 g, 61.08%).

MS:(ESI,pos.ion)m/z：771.3811[M+H] ⁺

Step 11: (S)-7-(4-((2-((1-(4-(4-hydroxynaphthalen-1-yl)phenyl)-3-methoxy-3-oxopropyl)amino)- 2-( ...

In a clean 100 mL single-necked flask, add (S)-tert-butyl 7-(4-((2-((1-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)-3-methoxy-3-oxopropyl)amino)-2-oxoethyl)amino)-4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (1.23 g, 1.60 mmol), methanol (18.5 mL) and 10% Pd/C (0.123 g), evacuate and replace with hydrogen, and react at room temperature under hydrogen atmosphere. Post-treatment: filter, concentrate the filtrate under reduced pressure, and purify by column chromatography (DCM/MeOH (V/V) = 40/1) to obtain the title compound as a yellow fluffy solid (446 mg, 40.92%).

MS:(ESI,pos.ion)m/z：681.3393[M+H] ⁺

Step 12: (S)-7-(4-((2-((1-(4-(4-((14-azido-3,6,9,12-tetraoxatetradecyl)oxy)naphthalen-1-yl)phenyl)-3-methoxy-3-oxopropyl)amino)-2-oxoethyl)amino)-4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylic acid tert-butyl ester (1-9)

In a clean 100 mL single-necked flask, (S)-tert-butyl 7-(4-((2-((1-(4-(4-hydroxynaphthalen-1-yl)phenyl)-3-methoxy-3-oxopropyl)amino)-2-oxoethyl)amino)-4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (0.446 g, 0.66 mmol), 14-azido-3,6,9,12-tetradecyl-4-methylbenzenesulfonate (0.547 g, 1.31 mmol), DMF (7 mL), potassium carbonate (0.226 g, 1.64 mmol) were added and the temperature was raised to 80°C for reaction. Post-treatment: water (30 mL) was added directly, extracted with ethyl acetate (20 mL×2), the organic phases were combined, washed with saturated brine (20 mL×4), dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography (DCM/MeOH (V/V)=40/1) to give the title compound as a yellow oil (0.497 g, 81.92%).

MS:(ESI,pos.ion)m/z：926.4772[M+H] ⁺

Step 13: (S)-3-(4-(4-((14-azido-3,6,9,12-tetrahydrotetradecyl)oxy)naphthalen-1-yl)phenyl)-3-(2-(4-(5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)butyramido)acetamido)propanoic acid (1)

In a clean 50 mL single-necked flask, (S)-tert-butyl 7-(4-((2-((1-(4-(4-((14-azido-3,6,9,12-tetraoxatetradecyl)oxy)naphthalen-1-yl)phenyl)-3-methoxy-3-oxopropyl)amino)-2-oxoethyl)amino)-4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (0.49 g, 0.53 mmol), tetrahydrofuran (7.4 mL), and LiOH (38.01 mg, 1.59 mmol) dissolved in water (7.4 mL) were added. The mixture was reacted at room temperature. After TLC detection showed that the starting material disappeared, 10% citric acid was added to adjust the pH to 4-5. The mixture was extracted with ethyl acetate (20 mL×3), dried over anhydrous sodium sulfate, filtered, and concentrated to obtain a white solid.

The obtained white solid was dissolved in DCM (9.6 mL), TFA (3.89 mL, 52.62 mmol) was added, and the reaction was stirred at room temperature.

Post-treatment: add saturated sodium bicarbonate solution to adjust the pH to neutral or weak alkaline, add dichloromethane (10 mL×2) for extraction, and purify by column chromatography (PE/EA (V/V) = 10/1) to obtain a light yellow oil (302 mg, 70.23%).

MS:(ESI,pos.ion)m/z：812.4041[M+H] ⁺

¹ H NMR (600MHz, Methanol-d4) δ8.33(dd,J＝8.4,1.2Hz,1H),7.75(d,J＝8.4Hz,1H),7.51(d,J＝8.2Hz,2H),7.45( ddd,J＝8.3,6.7,1.2Hz,1H),7.41-7.3 1(m,4H),7.21(d,J＝7.9Hz,1H),6.93(d,J＝7.9Hz,1H),6.48(d,J＝7.3Hz,1 H),5.34(t,J＝4.2Hz,1H),4.36-4.31(m,2H),4.04-3.98(m,2H),3.81-3.7 8(m,2H),3.72-3.69(m,2H),3.66-3.64(m,2H),3.63-3.53(m,8H),3.36- 3.33(m,2H),3.33-3.28(m,4H),2.92-2.63(m,6H),2.55(ddd,J＝13.6,7.5 ,3.2Hz,1H),2.37(ddd,J＝13.7,10.5,3.6Hz,1H),2.18(dtdd,J＝13.7,10. 7,5.6,3.3Hz,1H),2.02(tdd,J＝12.3,7.9,4.0Hz,1H),1.87-1.77(m,2H).

Example 2: (S)-3-(4-(4-((14-azido-3,6,9,12-tetrahydrotetradecyl)oxy)naphthalen-1-yl)phenyl)-3-(2-methyl-2-(4-(5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)butyramido)propanamido)propanoic acid (2)

Synthesis route:

Step 1: (S)-methyl 3-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)-3-((tert-butoxycarbonyl)amino)propanoate (2-1)

In a clean 250 mL single-necked flask, add (S)-methyl 3-(4-bromophenyl)-3-((tert-butoxycarbonyl)amino)propanoate (7.2 g, 20.10 mmol), tetrahydrofuran (144 mL), water (36 mL), 2-(4-(benzyloxy)naphthalen-1-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (7.24 g, 20.10 mmol), potassium phosphate (8.53 g, 40.20 mmol) and XPhos Pd G2 (789.7 mg, 1.01 mmol), replace and protect with nitrogen, and stir the reaction at room temperature. Post-treatment: ethyl acetate (100 mL) and water (200 mL) were added for separation, the aqueous phase was extracted with ethyl acetate (100 mL×3), the organic phases were combined, washed with saturated brine (200 mL×3), dried over anhydrous sodium sulfate, filtered, concentrated under reduced pressure, and purified by column chromatography (PE/EA (V/V)=2/1) to give the title compound as a colorless oily liquid (6.00 g, 58.37%).

Step 2: (S)-3-amino-3-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)propanoic acid methyl ester hydrochloride (2-2)

In a clean 100mL single-necked flask, add (S)-3-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)-3-((tert-butyloxycarbonyl)amino)propanoic acid methyl ester (4.5g, 8.80mmol) and 4mol/L dioxane hydrochloride solution (44mL), and stir at room temperature for reaction. Post-treatment: directly spin-dry for the next step to obtain a white solid (4.4g, yield 100%).

Step 3: Synthesis of methyl (S)-3-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)-3-(2-((tert-butyloxycarbonyl)amino)-2-methylpropionamido)propanoate (2-3)

In a clean 250 mL single-necked flask, (S)-methyl 3-amino-3-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)propanoate hydrochloride (4.40 g, 9.82 mmol), DMF (66 mL), N-tert-butoxycarbonyl-2-methylalanine (2.99 g, 14.73 mmol), HATU (7.47 g, 19.64 mmol), and DIPEA (6.35 g, 49.10 mmol) were added in sequence and the reaction was stirred at room temperature. Post-treatment: ethyl acetate (100 mL) and water (300 mL) were added for separation, the aqueous phase was extracted with ethyl acetate (100 mL × 2), the organic phases were combined, washed with saturated brine (300 mL × 3), dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure and purified by column chromatography (PE/EA (V/V) = 2/1) to give the title compound as a colorless oily liquid (5.50 g, 93.86%).

MS:(ESI,pos.ion)m/z：597.2989[M+H] ⁺

Step 4: (S)-3-(2-amino-2-methylpropionamido)-3-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)propanoic acid methyl ester hydrochloride (2-4)

In a clean 250mL single-necked flask, add (S)-3-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)-3-(2-((tert-butyloxycarbonyl)amino)-2-methylpropionamido)propanoic acid methyl ester (5.5g, 9.22mmol) and 4mol/L dioxane hydrochloride solution (46mL), and stir at room temperature to react. Post-treatment: directly spin-dry for the next step to obtain a brown solid (5g, yield 100%).

Step 5: (S)-7-(4-((1-((1-(4-(benzyloxy)naphthyl-1-yl)phenyl)-3-methoxy-3-oxopropyl)amino)-2-methyl-1-oxopropan-2-yl)amino)-4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylic acid tert-butyl ester (2-5)

In a clean 250mL single-necked flask, compound 1-5 (4-(8-(tert-butoxycarbonyl)-5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)butanoic acid, 2.10 g, 6.55 mmol), DMF (21 mL) and HATU (4.98 g, 13.1 mmol) were added, and DIPEA (4.23 g, 32.75 mmol) was added dropwise under ice bath. After the addition, the mixture was stirred at room temperature for 30 min. Then, (S)-3-(2-amino-2-methylpropionamido)-3-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)propionic acid methyl ester hydrochloride (5 g, 9.38 mmol) dissolved in DMF (21 mL) was added dropwise under ice bath, and the reaction was stirred at room temperature. Post-treatment: Add ethyl acetate (100 mL) and water (200 mL) to separate the liquids, extract the aqueous phase with ethyl acetate (100 mL × 2), combine the organic phases, wash with saturated brine (200 mL × 3), dry over anhydrous sodium sulfate, filter, concentrate the filtrate under reduced pressure, and purify by column chromatography (PE/EA (V/V) = 2/1) to obtain the title compound as a colorless oily liquid (2.7 g, 51.53%).

MS:(ESI,pos.ion)m/z：799.4177[M+H] ⁺

Step 6: (S)-7-(4-((1-((1-(4-(4-(4-hydroxynaphthalen-1-yl)phenyl)-3-methoxy-3-oxopropyl)amino)-2-methyl-1-oxopropan-2-yl)amino)-4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylic acid tert-butyl ester (2-6)

In a clean 100 mL single-necked flask, add (S)-7-(4-((1-((1-(4-(benzyloxy)naphthalen-1-yl)phenyl)-3-methoxy-3-oxopropyl)amino)-2-methyl-1-oxopropane-2-yl)amino)-4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylic acid tert-butyl ester (2.7 g, 3.38 mmol), methanol (54 mL), 10% Pd/C (0.81 g), replace with hydrogen and protect, and react at room temperature with stirring. Post-treatment: After filtration with diatomaceous earth pad, the filtrate was concentrated under reduced pressure and purified by column chromatography (PE/EA (V/V) = 2/1) to obtain the title compound as a colorless oily liquid (1.74 g, 72.5%).

MS:(ESI,pos.ion)m/z：709.3635[M+H] ⁺

Step 7: (S)-7-(4-((1-((1-(4-(4-((14-azido-3,6,9,12-tetraoxatetradecyl)oxy)naphthalen-1-yl)phenyl)-3-methoxy-3-oxopropyl)amino)-2-methyl-1-oxopropan-2-yl)amino)-4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylic acid tert-butyl ester (2-7)

In a clean 100 mL single-necked flask, (S)-tert-butyl 7-(4-((1-((1-(4-(4-(4-hydroxynaphthalen-1-yl)phenyl)-3-methoxy-3-oxopropyl)amino)-2-methyl-1-oxopropan-2-yl)amino)-4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (1.74 g, 2.45 mmol), DMF (26 mL), 14-azido-3,6,9,12-tetraoxatetradecyl 4-methylbenzenesulfonate (1.23 g, 2 .95mmol), add potassium carbonate (848.11mg, 6.14mmol) at 0℃, heat to 80℃ and stir to react. Post-treatment: add ethyl acetate (30mL) and water (120mL) to separate the liquids, extract the aqueous phase with ethyl acetate (30mL×3), combine the organic phases, wash with saturated brine (120mL×3), dry over anhydrous sodium sulfate, filter, concentrate the filtrate under reduced pressure, and purify by column chromatography (DCM/MeOH (V/V)＝40/1) to obtain the title compound as a colorless oily liquid (2.00g, 85.47%).

MS:(ESI,pos.ion)m/z：954.5011[M+H] ⁺

Step 8: (S)-3-(4-(4-((14-azido-3,6,9,12-tetraoxatetradecyl)oxy)naphthalen-1-yl)phenyl)-3-(2-(4-(8-(tert-butyloxycarbonyl)-5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)butyramido)-2-methylpropionamido)propanoic acid (2-8)

In a clean 100 mL single-necked flask, (S)-7-(4-((1-((1-(4-(4-((14-azido-3,6,9,12-tetraoxatetradecyl)oxy)naphthalen-1-yl)phenyl)-3-methoxy-3-oxopropyl)amino)-2-methyl-1-oxopropan-2-yl)amino)-4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylic acid tert-butyl ester (2.0 g, 2.10 mmol) and tetrahydrofuran (30 mL) were added. Lithium hydroxide (150.59 mg, 6.29 mmol) was dissolved in water (30 mL). Then add it to the above reaction system and stir the reaction at room temperature. Post-treatment: add 10% citric acid to adjust the pH to 4-6, add ethyl acetate (50mL) and water (200mL) to extract the liquid, extract the aqueous phase with ethyl acetate (50mL×3), combine the organic phases, wash with saturated brine (200mL×3), dry with anhydrous sodium sulfate, filter, concentrate the filtrate under reduced pressure, and purify by column chromatography (DCM/MeOH (V/V)＝10/1) to obtain the title compound as a colorless oily liquid (1.1g, 55.84%).

MS:(ESI,pos.ion)m/z：940.4873[M+H] ⁺

Step 9: (S)-3-(4-(4-((14-azido-3,6,9,12-tetraoxatetradecyl)oxy)naphthalen-1-yl)phenyl)-3-(2-methyl-2-(4-(5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)butanamido)propanamido)propanoic acid (2)

In a clean 100 mL single-necked flask, add (S)-3-(4-(4-((14-azido-3,6,9,12-tetraoxatetradecyl)oxy)naphthalen-1-yl)phenyl)-3-(2-(4-(8-(tert-butyloxycarbonyl)-5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)butanamido)-2-methylpropanamido)propanoic acid (1.10 g, 1.17 mmol), dichloromethane (22 mL) and trifluoroacetic acid (13.34 g, 117.01 mmol) and stir at room temperature to react. Post-treatment: After adjusting the pH to neutral with saturated sodium bicarbonate solution, dichloromethane (20 mL) and water (50 mL) were added for separation, the aqueous phase was extracted with dichloromethane (50 mL×3), the organic phases were combined, washed with saturated brine (50 mL×3), dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure and purified by column chromatography (DCM/MeOH (V/V)=20/1) to give the title compound as a colorless oily solid (532 mg, 54.13%).

MS:(ESI,pos.ion)m/z：840.4305[M+H] ⁺

¹ H NMR (600MHz, CDCl ₃ )δ10.86(s,1H),9.44(d,J＝8.2Hz,1H),8.35-8.32(m,1H),7.92(d,J＝8.4Hz,1H),7 .56(d,J＝8.0Hz,2H),7.46(ddd,J＝8.2,6.8,1.1Hz,1H),7.42-7.40(m,1H),7.38(d ,J＝8.2Hz,2H),7.29(s,0.5H),7.27(s,0.5H),7.21(d,J＝7.2Hz,1H),6.85(d,J＝7. 9Hz,1H),6.26(d,J＝7.3Hz,1H),5.77(s,1H),5.32(d,J＝5.4Hz,1H),4.36-4.32(m,2 H),4.05-4.01(m,2H),3.83(dd,J＝5.6,3.9Hz,2H),3.73(dd,J＝5.6,3.9Hz,2H),3. 70(dd,J＝3.6,1.8Hz,2H),3.68-3.61(m,8H),3.41(d,J＝4.5Hz,2H),3.39-3.35(m,2 H),3.02-2.86(m,4H),2.68(t,J＝6.0Hz,2H),2.43-2.39(m,1H),2.36-2.33(m,1H) ,2.07(tdd,J=17.4,10.2,7.0Hz,2H),1.89-1.84(m,2H),1.70(s,3H),1.58(s,3H).

Example 3: (S)-3-(4-(4-((14-azido-3,6,9,12-tetrahydrotetradecyl)oxy)naphthalen-1-yl)phenyl)-3-((2-((2-methoxyethyl)(4-(5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)butyl)amino)ethyl)amino)propanoic acid methyl ester (3)

Synthesis route:

Step 1: tert-Butyl 7-(4-hydroxybutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (3-9-2)

Add tert-butyl 7-(4-ethoxy-4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (5.00 g, 14.35 mmol) to a clean 250 mL single-mouth bottle, dissolve in anhydrous THF (50 mL), add 2 mol/L LiBH ₄ tetrahydrofuran solution (17.9 mL) dropwise at 0°C, and move to room temperature for reaction after addition. Post-treatment: add saturated ammonium chloride solution dropwise at 0°C to quench, extract with DCM (80 mL×2), combine the organic phases, dry over anhydrous sodium sulfate, and filter. Purify by column chromatography (DCM/MeOH (V/V)=20/1) to obtain a colorless oily compound (3.3 g, 75%).

Step 2: tert-Butyl 7-(4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (3-9)

In a clean 250 mL single-necked bottle, add tert-butyl 7-(4-hydroxybutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (3.00 g, 9.79 mmol) and dissolve it in DCM (30 mL). Slowly dropwise add the dissolved DCM (30 mL) Dess-Martin periodinane (DMP, 4.98 g, 11.74 mmol) was added and stirred at room temperature for 5 h. Post-treatment: filtration, washing the organic phase with saturated sodium chloride solution (40 mL), drying with anhydrous sodium sulfate, filtration, and column chromatography purification (PE/EA (V/V) = 1/1) to obtain a yellow oily compound (1.74 g, 58.39%).

Step 3: (2-Methoxyethyl)glycine methyl ester (3-2)

In a clean 250mL single-necked bottle, add 2-methoxyethane-1-amine (7.86g, 104.6mmol), potassium carbonate (29g, 209.18mmol), and dissolve in anhydrous THF (30mL). Add anhydrous THF (30mL) dropwise at 0°C to dissolve methyl 2-bromoacetate (8g, 52.3mmol). After the addition, move to room temperature to react overnight. Post-treatment: filtration, column chromatography purification (DCM/MeOH (V/V) = 20/1) to obtain a colorless liquid compound (6g, 77.9%).

Step 4: 2-((2-methoxyethyl)amino)1-ethanol (3-3)

Add (2-methoxyethyl)glycine methyl ester (5.85 g, 39.77 mmol) to a clean 250 mL three-necked flask, dissolve in anhydrous THF (46.8 mL), slowly drop 2.5 mol/L LiAlH ₄ tetrahydrofuran solution (47.7 mL, 119.31 mmol) at 0°C under N ₂ protection, move to room temperature and stir for 4 hours. Post-treatment: quench with water (4.7 mL) at 0°C, stir for 10 min, add 1 mol/L NaOH solution (4.7 mL), stir for 15 min, and add water (4.7 mL). Extract with EA (60 mL × 2), dry with anhydrous sodium sulfate, filter, and purify by column chromatography (DCM/MeOH (V/V) = 10/1) to obtain a brown liquid compound (2.49 g, 52.2%).

Step 5: (9H-fluoren-9-yl)methyl(2-hydroxyethyl)(2-methoxyethyl)carbamate (3-4)

In a clean 100 mL single-necked bottle, add 2-((2-methoxyethyl)amino)1-ethanol (1.64 g, 13.76 mmol), dissolve in acetonitrile (16 mL), add DIPEA (889.38 mg, 6.88 mmol), slowly dropwise add Fmoc-Cl (4.27 g, 16.52 mmol) dissolved in acetonitrile (16 mL), and stir at room temperature overnight. Post-treatment: purification by column chromatography (PE/EA (V/V) = 1/1) to obtain a yellow oily compound (2.8 g, 59.57%).

Step 6: (9H-fluoren-9-yl)methyl(2-methoxyethyl)(2-oxoethyl)carbamate (3-5)

In a clean 100mL single-mouth bottle, add (9H-fluoren-9-yl)methyl (2-hydroxyethyl) (2-methoxyethyl) carbamate (2.80g, 8.20mmol), dissolve in DCM (20mL), add Dess-Martin periodinane (DMP, 4.52g, 10.66mmol) in batches at 0°C, move to room temperature and stir to react for 6h. Post-treatment: filtration, washing with saturated sodium chloride solution (20mL×3), drying the organic phase with anhydrous sodium sulfate, filtration, column chromatography purification (PE/EA (V/V) = 1/1), to obtain a yellow oily compound (1.5g, 54%).

Step 7: Methyl (S)-3-((2-((((9H-fluoren-9-yl)methoxy)carbonyl)(2-methoxyethyl)amino)ethyl)amino)-3-(4-(4-(benzyloxy))1-naphthyl)phenyl)propanoate (3-6)

In a clean 100 mL single-necked bottle, add (9H-fluoren-9-yl)methyl (2-methoxyethyl) (2-oxoethyl) carbamate (1.50 g, 4.42 mmol), compound 2-2 ((S)-3-amino-3-(4-(4-(benzyloxy)naphthalen-1-yl) phenyl)propionic acid methyl ester hydrochloride, 2.36g, 5.28mmol), dissolved in methanol (30mL), dropped into AcOH (132.71mg, 2.21mmol), stirred at room temperature for 0.5h, then added NaBH(AcO) ₃ (1.87g, 8.84mmol) at 0℃, after addition, moved to room temperature and stirred to react overnight. Post-treatment: quenched by dropping saturated sodium bicarbonate solution at 0℃, extracted with DCM (30mL×2), dried over anhydrous sodium sulfate, filtered, purified by column chromatography (DCM/MeOH (V/V)＝20/1) to obtain a white solid compound (2.0g, 61.5%).

Step 8: Methyl (S)-3-((2-((((9H-fluoren-9-yl)methoxy)carbonyl)(2-methoxyethyl)amino)ethyl)(tert-butoxycarbonyl)amino)-3-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)propanoate (3-7)

In a clean 100 mL single-necked bottle, methyl (S)-3-((2-((((9H-fluoren-9-yl)methoxy)carbonyl)(2-methoxyethyl)amino)ethyl)amino)-3-(4-(4-(benzyloxy))1-naphthyl)phenyl)propanoate (2.0 g, 2.72 mmol) was added and dissolved in THF (10 mL). Sodium bicarbonate (685.86 mg, 8.16 mmol) dissolved in water was added. After stirring at room temperature for 0.5 h, Boc ₂ O (1.78 g, 8.16 mmol) was added. After the addition, the mixture was stirred at room temperature overnight. Post-treatment: EA (20 mL) was added for extraction and separation. 10% citric acid solution (20 mL) was added to the organic phase and stirred for 0.5 h. The mixture was separated, dried over anhydrous sodium sulfate, filtered, and purified by column chromatography (PE/EA (V/V) = 3/1) to obtain a white solid compound (2.0 g, 88.1%).

Step 9: (S)-methyl 3-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)-3-((tert-butoxycarbonyl)(2-((2-methoxyethyl)amino)ethyl)amino)propanoate (3-8)

In a clean 100 mL single-necked bottle, methyl (S)-3-((2-((((9H-fluoren-9-yl)methoxy)carbonyl)(2-methoxyethyl)amino)ethyl)(tert-butoxycarbonyl)amino)-3-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)propanoate (2.0 g, 2.40 mmol) was added, and dissolved in DCM (30 mL), and then DEA (30 mL) was added. After the addition, the mixture was stirred at room temperature overnight. Post-treatment: purification by column chromatography (DCM/MeOH (V/V) = 20/1) to obtain a colorless oily compound (1.3 g, 88.44%).

Step 10: Tert-butyl (S)-7-(4-((2-((1-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)-3-methoxy-3-oxopropyl)(tert-butoxycarbonyl))amino)ethyl)(2-methoxyethyl)amino)butyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (3-10)

In a clean 100 mL single-necked bottle, (S)-methyl 3-(4-(4-(benzyloxy)naphth-1-yl)phenyl)-3-((tert-butoxycarbonyl)(2-((2-methoxyethyl)amino)ethyl)amino)propanoate (1.3 g, 2.12 mmol), tert-butyl 7-(4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (839.50 mg, 2.76 mmol) were added, dissolved in methanol (26 mL), AcOH (63.70 mg, 1.06 mmol) was added dropwise, and the mixture was stirred at room temperature for 0.5 h after the addition. NaBH(AcO) ₃ (899.27 mg, 4.24 mmol) was added and stirred at room temperature overnight. Post-treatment: add saturated sodium bicarbonate solution to quench, extract with DCM (30 mL), dry with anhydrous sodium sulfate, filter and purify by column chromatography (DCM/MeOH (V/V) = 40/1) to obtain a light yellow oily compound (1.34 g, 69.9%).

MS:(ESI,pos.ion)m/z：901.516[M+H] ⁺

Step 11: Tert-butyl (S)-7-(4-((2-((tert-butoxycarbonyl)(1-(4-(4-hydroxynaphthalen-1-yl)phenyl)-3-methoxy-3-oxopropyl)amino)ethyl)(2-methoxyethyl)amino)butyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (3-11)

In a clean 100 mL single-necked bottle, tert-butyl (S)-7-(4-((2-((1-(4-(4-(benzyloxy)naphthalen-1-yl)phenyl)-3-methoxy-3-oxopropyl)(tert-butoxycarbonyl))amino)ethyl)(2-methoxyethyl)amino)butyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (1.18 g, 1.31 mmol) was added and dissolved in methanol (23.6 mL). Pd/C (472 mg, 0.4 g/g) was added and stirred at room temperature under _H2 atmosphere overnight. Post-treatment: filtration with diatomaceous earth pad and purification by column chromatography (DCM/MeOH (V/V) = 20/1) to obtain a light yellow solid compound (0.95 g, 89.45%).

Step 12: Tert-butyl (S)-7-(4-((2-((1-(4-(4-((14-azido-3,6,9,12-tetrahydrotetradecyl)oxy)naphthalen-1-yl))phenyl)-3-methoxy-3-oxopropyl)(tert-butoxycarbonyl)amino)ethyl)(2-methoxyethyl)amino)butyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (3-12)

In a clean 100 mL single-necked bottle, tert-butyl (S)-7-(4-((2-((tert-butoxycarbonyl)(1-(4-(4-hydroxynaphthalen-1-yl)phenyl)-3-methoxy-3-oxopropyl)amino)ethyl)(2-methoxyethyl)amino)butyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (950 mg, 1.17 mmol), 14-azido-3,6,9,12-tetrahydrotetradecyl 4-methylbenzenesulfonate (978.02 mg, 2.34 mmol) were added and dissolved in DMF (9.5 mL). Potassium carbonate (485.66 mg, 3.51 mmol) was added at 0°C. After the addition, the temperature was raised to 80°C and the reaction was stirred for 6 h. Post-treatment: lower the temperature to room temperature, add water (50 mL) and EA (20 mL) to extract and separate the liquids, wash the organic phase with water (20 mL×3), dry over anhydrous sodium sulfate, filter, and purify by column chromatography (DCM/MeOH (V/V)=20/1) to obtain a light yellow solid compound (1.1 g, 88.7%).

Step 13: (S)-3-(4-(4-((14-azido-3,6,9,12-tetrahydrotetradecyl)oxy)naphthalen-1-yl)phenyl)-3-((tert-butoxycarbonyl)(2-((4-(8-(tert-butoxycarbonyl)-5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)butyl)(2-methoxyethyl)amino)ethyl)amino)propanoic acid (3-13)

In a clean 100 mL single-necked bottle, tert-butyl (S)-7-(4-((2-((1-(4-(4-((14-azido-3,6,9,12-tetrahydrotetradecyl)oxy)naphthalen-1-yl))phenyl)-3-methoxy-3-oxopropyl)(tert-butoxycarbonyl)amino)ethyl)(2-methoxyethyl)amino)butyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (1.1 g, 1.04 mmol) was added and dissolved in THF (14.5 mL). LiOH (74.81 mg, 3.12 mmol) dissolved in water (16.5 mL) was added dropwise at 0°C. After the addition, the mixture was stirred at room temperature for 4 h. Post-treatment: add 10% citric acid aqueous solution to adjust the pH to about 4, extract with DCM (20 mL×3), dry with anhydrous sodium sulfate, filter, concentrate and dry to obtain a white solid compound (1.09 g, yield 100%).

Step 14: (S)-3-(4-(4-((14-azido-3,6,9,12-tetrahydrotetradecyl)oxy)naphthalen-1-yl)phenyl)-3-((2-((2-methoxyethyl))(4-(5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)butyl)amino)ethyl)amino)propanoic acid (3)

(S)-3-(4-(4-((14-azido-3,6,9,12-tetrahydrotetradecyl)oxy)naphthalen-1-yl)phenyl)-3-((tert-butoxycarbonyl)(2-((4-(8-(tert-butoxycarbonyl)-5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)butyl)(2-methoxyethyl)amino)ethyl)amino)propanoic acid (500 mg, 0.48 mmol) was weighed into a clean 50 mL single-mouth bottle, dissolved in DCM (10 mL), and TFA (8.2 g, 7.2 mmol) was added. The reaction was stirred at room temperature for 4 h. Post-treatment: quenched by adding saturated sodium bicarbonate solution, extracted with DCM (20 mL×2), dried over anhydrous sodium sulfate, filtered, and purified by wet-loading neutral alumina column chromatography (DCM/MeOH (V/V)=15/1). A light yellow compound (313 mg, 77.49%) was obtained.

MS:(ESI,pos.ion)m/z：842.494[M+H] ⁺

¹ H NMR (600MHz, CDCl ₃ )δ11.13(s,1H),8.37(d,J＝7.8Hz,1H),7.93(d,J＝8.1Hz,1H),7.53(d,J＝6.1Hz,2H),7.47(ddd, J＝17.0,10.8,4.0Hz,2H) ,7.43(d,J＝7.4Hz,2H),7.34(d,J＝7.8Hz,1H),7.21(d,J＝7.2Hz,1H),6.89(d,J＝7.9Hz,1H),6.26 (d,J＝7.2Hz,1H),4.40- 4.35(m,2H),4.16(d,J＝9.1Hz,1H),4.07-4.03(m,2H),3.84(dd,J＝5.6,3.9Hz,2H),3.75-3.72(m,2H) ,3.72-3.62(m,10H ),3.46(dd,J＝12.2,6.1Hz,4H),3.38(t,J＝5.1Hz,2H),3.33(s,3H),2.78-2.54(m,12H),1.98-1.85(m, 4H),1.27(s,4H).

Embodiment 4: (4)

Synthesis route:

Step 1: tert-Butyl 3-(2-(2-hydroxyethoxy)ethoxy)propanoate (4-9-2)

In a clean 50mL single-necked flask, add 2,2'-oxybis(ethan-1-ol) (2g, 18.85mmol), tert-butyl acrylate (0.725g, 5.65mmol), and dropwise add KOH (0.148g, 2.64mmol) dissolved in water (0.21mL). After the addition is complete, continue the reaction at room temperature. Post-treatment: add water (20mL), extract with ethyl acetate (30mL), wash the organic phase with saturated brine (30mL×4), dry over anhydrous sodium sulfate, filter, and purify by column chromatography (PE/EA (V/V)=1/2) to obtain the title compound as a colorless oil (1.30g, 98.81%).

MS:(ESI,pos.ion)m/z：179.0928[M-56+H] ⁺

Step 2: tert-Butyl 3-(2-(2-(tosyloxy)ethoxy)ethoxy)propanoate (4-9-3)

In a clean 50 mL single-necked flask, tert-butyl 3-(2-(2-hydroxyethoxy)ethoxy)propanoate (0.4 g, 1.71 mmol), DMAP (20.86 mg, 0.17 mmol), triethylamine (0.345 g, 3.41 mmol), and DCM (4 mL) were added. p-Toluenesulfonyl chloride (0.488 g, 2.51 mmol) was added at 0°C. After the addition, the mixture was stirred at room temperature for reaction. Post-treatment: water (30 mL) was added, and DCM was extracted (30 mL). The organic phase was dried over anhydrous sodium sulfate, filtered, and purified by column chromatography (PE/EA (V/V) = 2/1) to obtain the title compound as a light yellow oil (0.615 g, 92.76%).

MS:(ESI,pos.ion)m/z：333.1023[M-56+H] ⁺

Step 3: 3-(2-(2-(Tosyloxy)ethoxy)ethoxy)propanoic acid (4-9-4)

In a clean 50 mL single-necked flask, add tert-butyl 3-(2-(2-(toluenesulfonyloxy)ethoxy)ethoxy)propanoate (615 mg, 1.58 mmol), DCM (8 mL), TFA (1.44 g, 12.63 mmol) and stir at room temperature overnight. Post-treatment: add water (10 mL), extract with DCM (20 mL), and purify the organic phase with saturated sodium chloride. The residue was washed with water (10 mL x 2), dried over anhydrous sodium sulfate, filtered and concentrated to obtain the title compound as a yellow oil (0.531 g, based on 100%).

MS:(ESI,pos.ion)m/z：350.1339[M+H ₂ O] ⁺

Step 4: Benzyl 3-(2-(2-(tosyloxy)ethoxy)propanoate (4-9-5)

3-(2-(2-(toluenesulfonyloxy)ethoxy)ethoxy)propanoic acid (0.8 g, 2.41 mmol), benzyl alcohol (0.312 g, 2.89 mmol), DCM (8 mL) were added to a 50 mL single-mouth bottle, and EDCI (0.55 g, 2.89 mmol) and DMAP (29.41 mg, 0.241 mmol) were added after stirring at room temperature to dissolve, and the mixture was reacted at room temperature under nitrogen protection. Post-treatment: DCM (10 mL) and saturated brine (20 mL) were added to extract and separate the liquids, the organic phase was dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure and purified by column chromatography (PE/EA (V/V) = 1/1) to obtain the title compound as a colorless oil (0.744 g, 72.94%).

MS:(ESI,pos.ion)m/z：440.1845[M+H ₂ O] ⁺

Step 5: (S)-7-((2-)((1-(4-(2-(2-(3-)(benzyloxy)3-oxopropoxy)ethoxy)naphthalen-1-yl)phenyl)-3-methoxy-3-oxopropyl(amino)-4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (4-9-6)

In a 50 mL single-necked bottle, (S)-tert-butyl 7-((2-((4-(4-hydroxynaphthalen-1-yl)phenyl)-3-methoxy-3-oxoethyl)amino)-4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (0.1 g, 0.147 mmol), benzyl 3-(2-(2-(tosyloxy)ethoxy)propanoate (74.47 mg, 0.176 mmol), D MF (1.5 mL) was added with potassium carbonate (50.75 mg, 0.367 mmol) at 0°C and reacted at 80°C. Post-treatment: 20 mL of water and 15 mL of ethyl acetate were added to extract the separated liquid, the organic phase was washed with saturated brine (20 mL × 3), dried over anhydrous sodium sulfate, filtered, and purified by column chromatography (DCM/MeOH (V/V) = 30/1) to obtain the title compound as a colorless oil (83 mg, 60.58%).

MS:(ESI,pos.ion)m/z：931.4532[M+H] ⁺

Step 6: (S)-3-(2-)(4-(4-(1-)(2-(4-(8-(tert-butoxycarbonyl)-5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)butyrylamino))-3-methoxy-3-oxypropyl)phenyl)naphthalen-1-yl)oxy(ethoxy)ethoxy)propanoic acid (4-9)

In a clean 50 mL single-necked flask, (S)-7-((2-)((1-(4-(2-(2-(3-)(benzyloxy)3-oxopropoxy)ethoxy)naphthalen-1-yl)phenyl)-3-methoxy-3-oxopropyl(amino)-4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (83 mg, 89.14 μmol), methanol (1.25 mL), 10% palladium on carbon (8 mg, 0.1 g/g) were added, the hydrogen was replaced by vacuum, and the reaction was carried out at room temperature under a hydrogen atmosphere. Post-treatment: purification by column chromatography (DCM/MeOH (V/V) = 30/1) to obtain the title compound as an off-white solid (62.80 mg, 83.77%).

MS:(ESI,pos.ion)m/z：841.4142[M+H] ⁺

Step 7: Di-tert-butyl 3,3'-((2-amino-2-((3-(tert-butoxy)-3-oxopropoxy)methyl)propane-1,3-diyl)bis(oxy)dipropionate (4-2)

Add 2-amino-2-(hydroxymethyl)propanediol (10 g, 82.55 mmol) and DMSO (33 mL) to a clean 500 mL two-necked flask, add 5 mol/L sodium hydroxide aqueous solution (3.32 mL, 16.51 mmol) at 15°C, and drop tert-butyl acrylate (66.66 g, 520.08 mmol) under _N2 protection. After the drop is complete, transfer to room temperature for reaction. Post-treatment: add water (1 L) and ethyl acetate (0.5 L) to extract and separate, wash the organic phase with saturated brine (150 mL × 2), dry the organic phase with anhydrous sodium sulfate, filter, and purify by column chromatography (DCM/MeOH (V/V) = 50/1) to obtain the title compound as a colorless oil (21.54 g, 51.60%).

MS:(ESI,pos.ion)m/z：506.3344[M+H] ⁺

Step 8: tert-Butyl 7-(4-ethoxy-4-oxobutyl)-3,4-dihydro-1,8-naphthyridine-1(2H)-carboxylate (4-3)

In a clean 500mL three-necked flask, add di-tert-butyl 3,3'-((2-amino-2-((3-(tert-butoxy)-3-oxopropoxy)methyl)propane-1,3-diyl)bis(oxy)dipropionate (12 g, 23.73 mmol), tetrahydrofuran (48 mL), Fmoc-Osu (11.21 g, 33.22 mmol) and react at room temperature. Post-treatment: purification by column chromatography (PE/EA (V/V) = 6/1) to obtain the title compound as a colorless oil (14.21 g, 82.28%).

MS:(ESI,pos.ion)m/z:672.3440[M-56+H] ⁺

Step 9: 3,3-((2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-2-((2-carboxyethoxy)methyl)propane-1,3-diyl)bis(oxy))dipropanoic acid (4-4)

In a clean 500mL single-necked bottle, di-tert-butyl 3,3-((2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-2-((3-(tert-butyloxy)-3-oxopropoxy)methyl)propane-1,3-diyl)bis(oxy))dipropionate (14.2 g, 19.51 mmol) was weighed and dissolved in DCM (71.05 mL). TFA (71.05 mL) was added and the reaction was stirred at room temperature for 3 h after the addition was complete. Post-treatment: concentrated under reduced pressure to constant weight to obtain a yellow oily compound (10.92 g, yield 100%).

MS:(ESI,pos.ion)m/z：560.221[M+H] ⁺

Step 10: (9H-fluoren-9-yl)methyl di-tert-butyl (9-(12,12-dimethyl-5,10-dioxo-2,11-dioxa-6,9-diazatridecyl)-4,14-dioxo-7,11-dioxa-3,15-diazaheptadecan-1,9,17-triyl) tricarbamate (4-5)

3,3-((2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-2-((2-carboxyethoxy)methyl)propane-1,3-diyl)bis(oxy))dipropionic acid (10.90 g, 19.48 mmol) was weighed into a clean 500 mL single-necked bottle. HATU (37.04 g, 97.4 mmol) was dissolved in DCM (150 mL), stirred at room temperature for 1 h, and then tert-butyl (2-aminoethyl)carbamate (15.6 g, 97.4 mmol) was added at 0°C, and then DIPEA (25.18 g, 194.8 mmol) was added dropwise. After the addition, the mixture was stirred at room temperature for 3 h. Post-treatment: saturated sodium bicarbonate solution (100 mL) was added to extract and separate the liquids, and the organic phase was separated. The organic phase was washed with saturated sodium chloride solution (100 mL×2), dried over anhydrous sodium sulfate, filtered, and purified by column chromatography (DCM/MeOH (V/V)=20/1) to obtain a colorless oily compound (16.2 g, 84.33%).

MS:(ESI,pos.ion)m/z：986.553[M+H] ⁺

Step 11: (9H-fluoren-9-yl)methyl(1,17-diamino-9-((3-((2-aminoethyl)amino)-3-oxopropoxy)methyl)-4,14-dioxo-7,11-dioxa-3,15-diazaheptadecan-9-yl)carbamate hydrochloride (4-6)

In a clean 500mL single-mouth bottle, add (9H-fluoren-9-yl)methyl di-tert-butyl (9-(12,12-dimethyl-5,10-dioxo-2,11-dioxa-6,9-diazatridecyl)-4,14-dioxo-7,11-dioxa-3,15-diazaheptadecan-1,9,17-triyl) tricarbamate (16.20g, 16.43mmol), dissolve in 1,4-dioxane (64.8mL), add 4mol/L hydrochloric acid dioxane solution (64.8mL), stir at room temperature for 1.5h after addition. Post-treatment: concentrate under reduced pressure to constant weight to obtain a white solid compound (11.27g, 95.02%).

MS:(ESI,pos.ion)m/z：686.38[M+H] ⁺

Step 12: (9H-fluoren-9-yl)methyl di-tert-butyl (19-(22,22-dimethyl-5,10,20-trioxo-2,13,16,21-tetraoxa-6,9,19-triazatricosyl))-9,14,24,29-tetraoxo-3,6,17,21,32,35-hexaoxo-10,13,25,28-tetraazahepta(triacontane-1,19,37-triyl) tricarbamate (4-7)

2,2-dimethyl-4-oxo-3,8,11-trioxa-5-aza-14-oleic acid (16.41 g, 59.16 mmol), HATU (62.4 g, 164.3 mmol), DCM (220 mL) were weighed into a clean 500 mL single-necked bottle, dissolved, DIPEA (25.48 g, 197.16 mmol) was added at 0°C, and stirred at 0°C for 0.5 h. Then (9H-fluoren-9-yl)methyl (1,17-diamino-9-((3-((2-aminoethyl)amino)-3-oxopropoxy)methyl)-4,14-dioxo-7,11-dioxa-3,15-diazaheptadecane-9-yl)carbamate (11.27 g, 15.60 mmol) was slowly added at 0°C, and the mixture was stirred at room temperature for 3 h after the addition was completed. Post-treatment: add saturated sodium bicarbonate solution (150 mL) to extract and separate the liquid, separate the organic phase, wash the organic phase with saturated sodium chloride solution (150 mL×2), dry it with anhydrous sodium sulfate, filter it, and purify it by column chromatography (DCM/MeOH (V/V)=10/1) to obtain a brown oily compound (14.79 g, 64.75%).

MS: (ESI, pos.ion)m/z: 1463.81[M+H] ⁺

Step 13: (9H-fluoren-9-yl)methyl(1,37-diamino-19-(18-amino-5,10-dioxo-2,13,16-trioxa-6,9-diazaoctadecyl)-9,14,24,29-tetraoxo-3,6,17,21,32,35-hexaoxa-10,13,25,28-tetraazaheptadecan-19-yl)carbamate hydrochloride (4-8)

In a clean 50 mL single-necked bottle, weigh (9H-fluoren-9-yl)methyl di-tert-butyl (19-(22,22-dimethyl-5,10,20-trioxo-2,13,16,21-tetraoxa-6,9,19-triazatricosyl))-9,14,24,29-tetraoxo-3,6,17,21,32,35-hexaoxo-10,13,25,28-tetraazahepta(triacontane-1,19,37-triyl) tricarbamate (1 g, 683.19 μmol), dissolve in dioxane (3 mL), then add 4 mol/L hydrochloric acid dioxane solution (6 mL), and stir at room temperature for 4 h. Post-treatment: concentrate to constant weight to obtain the target compound as an off-white solid (1.23 g, yield 100%).

MS: (ESI, pos.ion)m/z:1163.6813[M+H] ⁺

Step 14: (4-10)

In a clean 50 mL single-necked bottle, (S)-3-(2-)(4-(4-(1-)(2-(4-(8-(tert-butoxycarbonyl)-5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)butyrylamino))-3-methoxy-3-oxypropyl)phenyl)naphthalen-1-yl)oxy(ethoxy)ethoxy)propanoic acid (585.52 mg, 0.696 mmol), HATU (0.882 g, 2.32 mmol), DCM (9 mL) were dissolved, stirred at room temperature for 0.5 h, and then slowly added ( 9H-fluoren-9-yl)methyl (1,37-diamino-19-(18-amino-5,10-dioxo-2,13,16-trioxa-6,9-diazaoctadecyl)-9,14,24,29-tetraoxo-3,6,17,21,32,35-hexaoxa-10,13,25,28-tetraazaheptadecan-19-yl) carbamate hydrochloride (225 mg, 0.188 mmol), DIPEA (0.50 g, 3.87 mmol) was added dropwise, and the mixture was stirred at room temperature for overnight reaction. Post-treatment: the mixture was washed with saturated sodium bicarbonate solution and saturated saline solution once, dried over anhydrous sodium sulfate, filtered, and purified by column chromatography (DCM/MeOH (V/V) = 12/1) to obtain an off-white solid (559 mg, 82.07%).

MS:(ESI,pos.ion)m/z:1816.9102[M/2+2H] ⁺

Step 15: (4-11)

4-10 (559 mg, 0.154 mmol), DCM (2.24 mL), and DEA (2.24 mL) were weighed into a clean 50 mL single-necked bottle and stirred at room temperature for 2 h. Post-treatment: concentrated under reduced pressure, wet loaded, purified by neutral alumina column chromatography (DCM/MeOH (V/V) = 20/1) to obtain a yellow oil (457 mg, 87.05%).

MS:(ESI,pos.ion)m/z:3408.73[M+H] ⁺

Step 16: (4-12)

Add 12-azidodecanoic acid (98.94 mg, 0.41 mmol), HATU (0.364 g, 0.957 mmol), and DCM (9.32 mL) to a clean 50 mL single-mouth bottle to dissolve. After stirring at room temperature for 0.5 h, slowly add 4-11 (0.466 g, 0.137 mmol) at 0 ° C, and drop DIPEA (0.21 g, 1.625 mmol). After the drop is completed, move to room temperature and stir to react overnight. Post-treatment: Add saturated sodium bicarbonate solution (10 mL) and DCM (10 mL) to extract and separate the liquids. Wash the organic phase with saturated sodium chloride solution (10 mL), dry it with anhydrous sodium sulfate, filter it, and purify it by column chromatography. (DCM/MeOH (V/V) = 10/1) to give an off-white solid (0.39 g, 78.55%).

MS:(ESI,pos.ion)m/z:3632.93[M+2H] ⁺

Step 17: (4)

Add 4-12 (0.39 g, 107.34 μmol) and THF (3.9 mL) to a clean 50 mL single-mouth bottle to dissolve. After stirring at room temperature, add LiOH (23.13 mg, 966.06 μmol) dissolved in water (3.9 mL). After the addition, move to room temperature and stir to react overnight. Post-treatment: adjust pH to 4 with 10% citric acid, extract with a mixed solution of (DCM: MeOH = 6:1) (10 mL × 4), combine the organic phases, dry over anhydrous sodium sulfate, filter, and concentrate to constant weight. The resulting 0.38 g residue is dissolved in dichloromethane (3.9 mL), TFA (3.9 mL) is added, stirred at room temperature for 7 h, concentrated under reduced pressure to constant weight, and lyophilized to obtain a viscous white solid (203 mg, 55.80%) by reverse phase column chromatography (acetonitrile: water = 1:1).

MS:(ESI,pos.ion)m/z:3290.71[M+2H] ⁺

¹ H NMR(600MHz,MeOD)δ8.35(d,J＝8.4Hz,3H),7.76(d,J＝8.5Hz,3H),7.55-7.45 (m,12H),7.41(t,J＝8.2Hz,9H),7.26(d,J＝7.9Hz,3H),6.97(d,J＝8.0Hz,3H), 6.60(d,J＝7.3Hz,3H),5.51(t,J＝7.1Hz,3H),4.37-4.30(m,6H),4.04-4.00( m,6H),3.99(s,2H),3.94(s,2H),3.82-3.77(m,6H),3.76(t,J＝6.1Hz,6H),3. 72-3.58(m,24H),3.53(t,J＝4.8Hz,12H),3.46(dt,J＝6.5,4.8Hz,12H),3.33 (d,J＝1.5Hz,8H),3.28(s,12H),2.99-2.90(m,6H),2.78-2.66(m,12H),2.52- 2.37(m,18H),2.34(td,J＝7.0,4.0Hz,6H),2.16(t,J＝7.5Hz,2H),2.04-1.96 (m,6H),1.93-1.86(m,6H),1.54(dd,J＝14.4,7.0Hz,4H),1.34-1.24(m,16H).

Example 5 Evaluation of integrin αvβ6 ELISA binding assay

Objective To evaluate the potential inhibitory effect of compounds on integrin αvβ6 in an ELISA binding assay. Reagents and instruments

RCTS-001 was prepared according to Chinese patent CN201880070813.4, and its structure is

Experimental procedures

1. Buffer preparation.

2. A flat-bottom 96-well ELISA plate was coated with TGF-β1 in carbonate buffer (80 μL per well) overnight at 4°C.

3. Washing: Wash the wells three times with 200 μl of washing buffer per well.

4. Block with 150 μl of assay buffer per well for 1 h at 25°C. Prepare reference CWHM-12 serially diluted 3-fold from 100 μM in DMSO for 10 doses and serially dilute compounds 10-fold from 2 mM in DMSO to obtain 10 doses. Prepare 2 serial dilutions of reference and test compounds: transfer 1 μL 100X reference CWHM-12 or test compound to 99 μL 1X assay buffer. Prepare 2X His Tag αvβ6 protein in assay buffer.

5. Wash: Repeat step 3.

6. Add samples: Add 25 μl 2X HisTag αvβ6 protein and 25 μl 2X compound dilution to each well, centrifuge the 96-well plate at 1000 rpm for 1 minute, and incubate at 25°C for 1 hour.

7. Wash: Repeat step 3.

8. Prepare the primary antibody (anti-αv mouse anti-human), add 50 μl of primary antibody in buffer to each well and incubate at 25C for 1 hour.

9. Wash: Repeat step 3.

10. Prepare secondary peroxidase-labeled antibody (Peroxidase Conjμgated, H+L), add 50μl of secondary peroxidase-labeled antibody in buffer to each well, centrifuge the 96-well plate at 1000rpm for 1 minute, and incubate at 25°C for 1 hour.

11. Washing: Repeat step 3.

12. Add substrate: Add 30 μl of substrate solution to each well, centrifuge the 96-well plate at 1000 rpm for 1 minute, and incubate at 25°C for 40 minutes.

13. Stop: Add 30 μl of stop solution to each well and centrifuge the 96-well plate at 1000 rpm for 1 minute.

14. Read the fluorescence signal on the plate using OD450 on the BMG.

Data analysis

The calculation method of inhibition % is as follows:

ABS: Absorbance

Average absorbance of the positive control across the plate

Average absorbance of the negative control for the entire plate

Calculate IC50 and plot effect-dose curves of compounds

IC50 (dose response - variable slope) was calculated by fitting % inhibition values and the logarithm of compound concentration using Graphpad 8.0.
Y＝Bottom+(Top-Bottom)/(1+10^((LogIC50-X)*Hill Slope))

X:log of inhibitor concentration；Y:%Inhibition

Experimental Results

The experimental results show that the integrin ligand compound (1) of the present invention has an IC50 of 2.12 nM, which is better than RCTS-001. Compound (4) and RCTS-001 show the same excellent targeting and inhibitory effects, while compound (3) and compound (2) show better targeting and inhibitory effects. The inventors subsequently conducted cell adhesion tests on the integrin ligand compounds (1), (2), (3) and (4) of the present invention, and administered RNAi agents conjugated with the αvβ6 integrin ligand of the present invention to rats, which showed excellent pharmacodynamic activity. Comprehensive evaluation shows that the compounds designed by the present invention have good targeting and inhibitory effects on integrin αvβ6, and have excellent pharmacodynamic activity after further combining with RNAi agents, and the comprehensive evaluation is relatively good.

The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims (41)

A compound represented by the following formula I, its tautomer or a pharmaceutically acceptable salt thereof, is:
in, Ring A is selected from optionally substituted C _3-10 cycloalkyl, 3-10 membered heterocycloalkyl and phenyl; n is an integer from 0 to 7; J is selected from C-H or N; X is selected from -CH ₂ -, -C(=O)-; Y is selected from -CH ₂ -, -C(=O)-; Z is selected from OR ₆ , N(R ₆ ) ₂ or SR ₆ ; R ₁ is selected from H, optionally substituted alkyl; _R2 is selected from H, optionally substituted alkyl; _R3 is selected from aryl optionally substituted by _R7 , optionally substituted heteroaryl, optionally substituted heterocyclyl, optionally substituted cycloalkyl, or _R3 comprises a transported molecule; R ₄ is selected from H, C _1-3 alkyl; R ₅ is selected from H, C _1-3 alkyl; Each R ₆ is independently selected from H, optionally substituted alkyl, or R ₆ comprises a transported molecule; wherein the substituents in ring A, R ₁ , R ₂ and R ₆ are independently selected from halogen, CF ₃ , OH, NH ₂ , C _{1- 6} alkoxy, and the number of substituents in each group is independently selected from 1, 2 or 3; _R7 is selected from one or more divalent cyclic moieties having 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 carbon atoms optionally substituted with _R8 , wherein _R8 comprises one or more molecules to be transported. The compound according to claim 1, characterized in that, wherein n is 3, X is selected from -CH ₂ -, Y is selected from -CH ₂ -, and Z is selected from OH. The compound according to claim 1, characterized in that, wherein n is 3, X is selected from -C(=O)-, Y is selected from -C(=O)-, and Z is OH. The compound according to claim 1, characterized in that, wherein the R ₁ is selected from _R2 is selected from H, _R3 is selected from phenyl, _R4 is selected from H, and _R5 is selected from H. The compound according to claim 1, characterized in that, wherein R ₁ is selected from H, R ₂ is selected from H, R ₃ is selected from phenyl, R ₄ is selected from H, and R ₅ is selected from H. The compound according to claim 1, characterized in that, wherein R ₁ is selected from H, R ₂ is selected from H, R ₃ is selected from phenyl, R ₄ is selected from methyl, and R ₅ is selected from methyl. The compound according to claim 1, characterized in that, wherein the ring A is selected from The compound according to claim 1, characterized in that, wherein J is selected from N. The compound according to claim 1, characterized in that the divalent cyclic portion includes a cycloalkyl, a cycloalkenyl, an aryl, a heteroaryl or a heterocyclic group, the cycloalkyl is a cyclopropyl, a cyclobutyl, a cyclopentyl, a cyclohexyl or a cycloheptyl, the cycloalkenyl is a cyclopentenyl, a cyclobutenyl, a cyclopentenyl, a cyclohexenyl or a cycloheptenyl, the aryl is a phenyl or a naphthyl, the heteroaryl is a pyridyl, a pyrimidinyl, a pyridazinyl, a pyrrole, a pyrazole, an imidazole, a thiophene, a benzothiophene, a thiazole, a benzothiazole, a furan, an oxazole, an isoxazole, a benzofuran, an indole, an indazole, a benzimidazole, an oxadiazole, a 1,2,3-triazole, a 1,2,4-triazole, a tetrazole, a quinolyl, an isoquinolyl or a quinoxalinyl, the heterocyclic group is a tetrahydrofuran, a tetrahydropyran, a piperidine, a pyrrolidine, a dioxane or a dioxolane. A compound of the formula, a tautomer thereof, or a pharmaceutically acceptable salt thereof,
wherein R ₉ comprises the molecule to be transported. The compound according to any one of claims 1 to 10, characterized in that it further comprises a polyethylene glycol linker having 2 to 20 ethylene oxide units. A compound of the following formula, a tautomer thereof or a pharmaceutically acceptable salt thereof, wherein the compound is selected from
in The point of attachment to the portion comprising the molecule being transported is indicated. A compound of the following formula, a tautomer thereof or a pharmaceutically acceptable salt thereof, wherein the compound is selected from

in The point of attachment to the portion comprising the molecule being transported is indicated. The compound according to any one of claims 1 to 13, wherein the transported molecule is an active pharmaceutical ingredient or a prodrug. The compound according to any one of claims 1 to 13, characterized in that the transported molecule comprises a small molecule, an antibody, an antibody fragment, an immunoglobulin, a monoclonal antibody, a label or marker, a lipid, a natural or modified nucleic acid, a natural or modified nucleic acid oligonucleotide, a natural or modified nucleic acid polynucleotide, a peptide, a nucleic acid aptamer, a polymer, a polyamine, a protein, a toxin, a vitamin, polyethylene glycol, a hapten, digoxigenin, biotin, a radioactive atom or molecule, or a fluorophore. The compound according to any one of claims 1 to 13, wherein the transported molecule comprises a RNAi agent. A structure, characterized in that it comprises a compound according to any one of claims 1 to 16, a linker and a scaffold, wherein the structure is bound to a transported molecule and the compound is an αvβ6 ligand. The structure according to claim 17 is characterized in that the structure comprises a monodentate form of an αvβ6 integrin ligand. The structure according to claim 17 is characterized in that the structure comprises a bidentate αvβ6 integrin ligand. The structure according to claim 17 is characterized in that the structure comprises a tridentate αvβ6 integrin ligand. The structure according to claim 17 is characterized in that the structure comprises a tetradentate form of an αvβ6 integrin ligand. The structure according to claim 17, wherein the bracket has the following formula:
in " represents the RNAi agent, and "αvβ6 ligand" represents the respective ligand structure and linker. A compound as shown in the following formula Ib, its tautomer or a pharmaceutically acceptable salt thereof, wherein the compound is an αvβ6 integrin ligand precursor, and comprises the structure:
in, Ring A is selected from optionally substituted C _3-10 cycloalkyl, 3-10 membered heterocycloalkyl and phenyl; n is an integer from 0 to 7; J is selected from C-H or N; X is selected from -CH ₂ -, -C(=O)-; Y is selected from -CH ₂ -, -C(=O)-; Z is selected from OR ₆ , N(R ₆ ) ₂ or SR ₆ ; R ₁ is selected from H, optionally substituted alkyl; _R2 is selected from H, optionally substituted alkyl; _R3 is selected from aryl optionally substituted by _R7 , optionally substituted heteroaryl, optionally substituted heterocyclyl, optionally substituted cycloalkyl, or _R3 comprises a linker conjugated to a reactive group; R ₄ is selected from H, C _1-3 alkyl; R ₅ is selected from H, C _1-3 alkyl; Each R ₆ is independently H, optionally substituted alkyl, or R ₆ comprises a linker group that is transported or conjugated to a reactive group; wherein the substituents in ring A, R ₁ , R ₂ and R ₆ are independently selected from halogen, CF ₃ , OH, NH ₂ , C _{1- 6} alkoxy, and the number of substituents in each group is independently selected from 1, 2 or 3; _R7 is selected from the group consisting of one or more divalent cyclic moieties having 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 carbon atoms optionally substituted with _R8 , wherein _R8 comprises a linking group conjugated to a reactive group. The compound according to claim 23, characterized in that the linking group is a PEG linker. The compound according to claim 23, characterized in that the PEG linker comprises 2-20 PEG units. The compound according to claim 23, characterized in that the reactive group is an azide. The compound according to claim 23, wherein the linking group conjugated to the reactive group has the structure:
where m is an integer from 2 to 20, and represents the point of attachment to the structure of Formula Ib. An αvβ6 integrin ligand precursor, a tautomer thereof or a pharmaceutically acceptable salt thereof, which is selected from:
An αvβ6 integrin ligand precursor, a tautomer thereof or a pharmaceutically acceptable salt thereof, which is selected from:

A composition comprising a compound according to any one of claims 1 to 16 or a structure according to any one of claims 17 to 22, and a pharmaceutically acceptable excipient. The composition of claim 30, wherein the compound is conjugated to an oligonucleotide-based compound capable of inhibiting target gene expression in epithelial cells. The composition of claim 30, wherein the compound is conjugated to an RNAi agent capable of inhibiting target gene expression in epithelial cells. The composition of claim 30, wherein the compound is conjugated to an RNAi agent capable of inhibiting target gene expression in bronchiolar epithelial cells. A method of delivering one or more transported molecules to a cell, the method comprising administering to the cell a compound of any one of claims 1-16 or a structure of any one of claims 17-22. A method for delivering one or more transported molecules to a cell or tissue of a subject in vivo, the method comprising administering to the subject a compound of any one of claims 1-16, a structure of any one of claims 17-22, or a composition of any one of claims 30-33. The method according to claim 34 or 35, characterized in that the cells are selected from type I and type II alveolar epithelial cells, goblet cells, secretory epithelial cells, ciliated epithelial cells, corneal and conjunctival epithelial cells, dermal epithelial cells, bile duct epithelial cells, intestinal epithelial cells, ductal epithelial cells, glandular epithelial cells and epithelial tumor cancer. The method according to any one of claims 34-36, characterized in that one or more of the transported molecules comprises an oligonucleotide-based compound. The method of claim 37, wherein the oligonucleotide-based compound is a RNAi agent. A method of inhibiting target gene expression in a cell in vivo, the method comprising administering to a subject an effective amount of a composition comprising an oligonucleotide-based compound conjugated to a compound of any one of claims 1-16. The method of claim 39, wherein the cells are selected from type I and type II alveolar epithelial cells, goblet cells, secretory epithelial cells, ciliated epithelial cells, corneal and conjunctival epithelial cells, dermal epithelial cells, bile duct epithelial cells, intestinal epithelial cells, ductal epithelial cells, glandular epithelial cells and epithelial tumors. The method of claim 39, wherein the oligonucleotide-based compound is a RNAi agent.