RU2838538C1 - 7-substituted sulphonimidoylpurinones for treating and preventing viral infection - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: present invention relates to a method for stimulating production of HBV-specific antibodies using a compound selected from: 6-amino-9-benzyl-N-methyl-8-oxo-N-propyl-2-(propylsulphonimidoyl)purine-7-carboxamide, 6-amino-9-[(4-chlorophenyl)methyl]-2-[S(R)-ethylsulphonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide, 6-amino-9-[(4-chlorophenyl)methyl]-2-[S(S)-ethylsulphonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide, 6-amino-9-[(4-chlorophenyl)methyl]-N-ethyl-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-purine-7-carboxamide, 6-amino-9-[(4-chlorophenyl)methyl]-N-ethyl-2-[S(R)-ethylsulphonimidoyl]-N-methyl-8-oxo-purine-7-carboxamide, 6-amino-2-[S(R)-ethylsulphonimidoyl]-N-methyl-8-oxo-N-propyl-9-(p-tolylmethyl)purine-7-carboxamide, 6-amino-2-[S(S)-ethylsulphonimidoyl]-N-methyl-8-oxo-N-propyl-9-(p-tolylmethyl)purine-7-carboxamide, 6-amino-N-ethyl-2-[S(S)-ethylsulphonimdoyl]-N-methyl-8-oxo-9-(p-tolylmethyl)purine-7-carboxamide, 6-amino-N-ethyl-2-[S(R)-ethylsulphonimidoyl]-N-methyl-8-oxo-9-(p-tolylmethyl)purine-7-carboxamide, 6-amino-2-(ethylsulphonimidoyl)-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide, 6-amino-2-[S(R)-ethylsulphonimidoyl]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide, 6-amino-2-[S(S)-ethylsulphonimidoyl]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide, 6-amino-9-[(4-bromophenyl)methyl]-2-(ethylsulphonimidoyl)-N-methyl-8-oxo-N-propyl-purine-7-carboxamide, 6-amino-2-[S(R)-ethylsulphonimidoyl]-9-[(4-bromophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide, 6-amino-2-[S(S)-ethylsulphonimidoyl]-9-[(4-bromophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide, 6-amino-9-[(4-bromophenyl)methyl]-N-ethyl-2-(ethylsulphonimidoyl)-N-methyl-8-oxo-purine-7-carboxamide, 6-amino-9-[(4-bromophenyl)methyl]-N-ethyl-2-[S(S)-(ethylsulphonimidoyl)]-N-methyl-8-oxo-purine-7-carboxamide, 6-amino-9-[(4-bromophenyl)methyl]-N-ethyl-2-[S(R)-(ethylsulphonimidoyl)]-N-methyl-8-oxo-purine-7-carboxamide or pharmaceutically acceptable salts thereof, enantiomers or diastereomers.

EFFECT: invention provides stimulation of production of HBV-specific antibodies.

1 cl, 7 dwg, 14 tbl, 57 ex

Description

This application is separated from application No. 2019107957 for the issuance of a Russian Federation patent for an invention, filed on August 28, 2017, claiming multiple priority based on the filing dates of application PCT/CN 2016/097140, filed on August 29, 2016, and application PCT/CN 2017/092653, filed on July 12, 2017.

The present invention relates to new derivatives of sulfonimidoylpurinones that have agonistic activity in vivo with respect to Toll-like receptors, as well as to their production, to pharmaceutical compositions containing them and their possible use as medicinal products.

FIELD OF INVENTION

The present invention relates to compounds of formula (I),

wherein R ¹ - R ³ are as defined below, or a pharmaceutically acceptable salt, enantiomer or diastereomer thereof.

Toll-like receptors (TLRs) recognize a broad range of conserved pathogen-associated molecular patterns (PAMPs). They play an important role in the detection of invading pathogens and the subsequent initiation of innate immune responses. In humans, there are 10 members of the TLR family, which are type I transmembrane proteins characterized by an extracellular leucine-rich domain and a cytoplasmic tail containing a conserved Toll-like receptor/interleukin (IL)-1 receptor (TIR) domain. Members of this family, ^TLR3 , TLR7, TLR8, and TLR9, are located in endosomes. TLR7 can be activated by binding to a specific small molecule ligand (e.g., a TLR7 agonist) or its native ligand (e.g., single-stranded RNA, ssRNA). It is believed that after ssRNA binds to TLR7, the receptor in its dimerized form undergoes a structural change leading to subsequent recruitment of adaptor proteins to its cytoplasmic domain including myeloid differentiation primary gene response protein 88 (MyD88). Following initiation of the signaling cascade involving receptors of the MyD88-mediated pathway, cytoplasmic transcription factors such as interferon regulatory factor 7 (IRF-7) and nuclear factor kappa B (NF-κB) are activated. These transcription factors then translocate to the nucleus and initiate transcription of various genes such as interferon-alpha (IFN-α) and other antiviral cytokines. In most cases, TLR7 is expressed on plasmacytoid cells and also on B cells. Altered immune cell susceptibility may contribute to the attenuation of innate immune responses in chronic viral infections. Therefore, agonist-induced TLR7 activation may represent a new approach to the treatment of chronic viral infections (DJ Connolly and L. AJ O'Neill, Current Opinion in Pharmacology, 2012, 12: 510-518, PA Roethle et al., J. Med. Chem., 2013, 56, 7324-7333).

Current therapy for chronic hepatitis B virus (HBV) infection is based on two different types of drugs: traditional antiviral nucleos(t)ide analogues and the recently developed PEGylated IFN-α (polyethylene glycol (PEG)-IFN-α). Oral nucleos(t)ide analogues act by inhibiting HBV replication. This is a lifelong treatment regimen during which drug resistance often occurs. PEGylated IFN-α (PEG-IFN-α) has been used as an alternative treatment option for some patients with chronic HBV infection within a defined therapy period. Although seroconversion to the HBV e antigen (HBeAg) is achieved in at least a small percentage of patients with HBV infection, adverse effects make it poorly tolerated. Notably, in both cases of current therapy, functional cure, defined as HBV surface antigen (HBsAg) seroconversion, is very rare. Therefore, the development of a new generation of therapeutic agent for the treatment of patients with HBV infection with the goal of functional cure is an urgent need. Treatment with an oral TLR7 agonist represents a promising solution to provide greater efficacy with better tolerability. Currently, pegylated IFN-α (PEG-IFN-α) is used for the treatment of chronic HBV infection, which represents an alternative to possibly lifelong treatment with antiviral nucleos(t)ide analogues. In a subset of patients with chronic HBV infection, therapy with PEG-IFN-α can induce sustained immunological control of the virus after a certain duration of therapy. However, the percentage of patients with HBV infection who achieve seroconversion with interferon therapy is low (up to 27% for HBeAg-positive patients) and such treatment is generally poorly tolerated. Furthermore, functional cure (defined as HBsAg loss and seroconversion) is also very infrequently observed with either PEG-IFN-α or nucleos(t)ides. Given these limitations, there is an unmet need for improved therapeutic options and for achieving functional cure of chronic HBV infection. Treatment with an oral small molecule TLR7 agonist is a promising approach with the potential to provide improved efficacy and tolerability (T. Asselah et al., Clin. Liver Dis., 2007, 11, 839-849).

In fact, several identified TLR7 agonists have been evaluated for therapeutic applications. To date, imiquimod (ALDARA™) is a TLR7 agonist drug approved by the US Food and Drug Administration (FDA) for topical use in the treatment of skin lesions caused by human papillomavirus (HPV) and rhinitis media. The dual-acting TLR7/8 agonist resiquimod (R-848) and the TLR7 agonist 852A have been evaluated for the treatment of human genital herpes and chemoresistant metastatic melanoma, respectively. ANA773 is an orally administered TLR7 agonist prodrug developed for the treatment of patients with chronic hepatitis C virus (HCV) infection and chronic hepatitis B virus infection. GS-9620 is an orally administered TLR7 agonist. In a phase Ib trial, GS-9620 treatment was shown to be safe, well tolerated, and resulted in dose-dependent induction of ISG15 (interferon-stimulated gene 15) mRNA in patients with chronic hepatitis B (E.J. Gane et al., Annu. Meet. Am. Assoc. Study Liver Dis. (November 1-5, Washington, D.C.) 2013, Abst. 946). Thus, there is a great unmet clinical need to develop potent and safe TLR7 agonists as novel agents for the treatment of HBV infection, with the aim of providing additional therapeutic options or replacing existing partially effective regimens.

ESSENCE OF THE INVENTION

According to the present invention, there are provided a series of new 6-amino-2-sulfonimidoyl-9-substituted-7-substituted-purin-8-one compounds having agonistic activity towards Toll-like receptors and their prodrugs. According to the invention, there is also provided biological activity of such compounds for the purpose of inducing an increase in the level of SEAP (secreted embryonic alkaline phosphatase) by activating Toll-like receptors, such as the TLR7 receptor, metabolic conversion of prodrugs to the parent compounds in the presence of human hepatocytes and therapeutic or prophylactic use of such compounds and pharmaceutical compositions containing these compounds and their prodrugs for the treatment or prevention of an infectious disease such as HBV or HCV infection. According to the present invention, there are also provided compounds with very high activity. In addition, the compounds of formula (I) also exhibit good solubility profiles and pharmacokinetic (PK) profiles.

The present invention relates to new compounds of formula (I),

Where

R ¹ is C _1-6 alkyl;

R ² is benzyl, wherein said benzyl is unsubstituted or substituted with one, two or three substituents independently selected from halogen and

C _1-6 alkyl;

R ³ is -NR ⁴ R ⁵ , where

R ⁴ is C _1-6 alkyl or C _1-6 alkoxyC _1-6 alkyl;

R ⁵ is (C _1-6 alkyl) ₂ NCOOC _1-6 alkyl, C _1-6 alkoxyC _1-6 alkyl, C _1-6 alkoxycarbonyl(C _1-6 alkyl)aminoC _1-6 alkyl, C _1-6 alkoxycarbonyl(phenyl)C _1-6 alkyl, C _1-6 alkoxycarbonylC _1-6 alkyl, C _{1-6 alkyl} alkoxycarbonyloxyC _1-6 alkyl, 6 alkyl, C _1-6 alkylcarbonyl(C _1-6 alkyl) aminoC _1-6 alkyl or pyrrolidinylcarbamoyloxyC _1-6 alkyl; or

R ⁴ and R ⁵ together with the nitrogen atom to which they are attached form a heterocyclyl;

or a pharmaceutically acceptable salt, enantiomer or diastereomer thereof; provided that

6-amino-9-benzyl-2-(propylsulfonimidoyl)-7-(pyrrolidine-1-carbonyl)purin-8-one;

6-amino-9-benzyl-7-(piperidine-1-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-7-(morpholine-4-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-7-(3,3-dimethylpyrrolidine-1-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

ethyl 1-[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]pyrrolidine-2-carboxylate;

6-amino-7-(2-azaspiro[3.3]heptane-2-carbonyl)-9-benzyl-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-7-(2-oxa-6-azaspiro[3.3]heptane-6-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-7-(3,3-difluoropyrrolidine-1-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-7-(3-fluoro-3-methyl-pyrrolidine-1-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

and their enantiomers or diastereomers.

The present invention also relates to their production, medicinal products based on the compound of the invention and their preparation, as well as to the use of such compounds of formula (I) as a TLR7 agonist. Accordingly, the compounds of formula (I) are useful for the treatment or prevention of HBV and/or HCV infection by agonism in relation to Toll-like receptors.

DETAILED DESCRIPTION OF THE INVENTION

Unless otherwise defined, all technical and scientific terms used in this specification have exactly the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In addition, the following definitions are provided to illustrate and define the meaning and scope of various terms used to describe this invention.

DEFINITIONS

The term "C _1-6 alkyl" means a saturated straight or branched chain alkyl group containing 1-6, in particular 1-4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, and the like. Particular "C _1-6 alkyl" groups are methyl, ethyl, and n-propyl.

The term "C _1-6 alkoxy" means a group of the formula C _1-6 alkyl-O-. Examples of C _1-6 alkoxy groups include, but are not limited to, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, and tert-butoxy. Particular "C _1-6 alkoxy" groups are methoxy, ethoxy, and isopropoxy. A more specific C _1-6 alkoxy group is ethoxy.

The terms "halogen" and "halogen atom" are used interchangeably herein and mean fluorine, chlorine, bromine or iodine.

The term "heterocyclyl" refers to a monovalent saturated or partially unsaturated mono- or bicyclic ring system of 3-10 ring atoms containing 1-5 ring heteroatoms selected from N, O, and S, the remaining ring atoms being carbon atoms. In particular embodiments, heterocyclyl is a monovalent saturated monocyclic ring system of 4-7 ring atoms containing 1, 2, or 3 ring heteroatoms selected from N, O, and S, the remaining ring atoms being carbon atoms. Examples of monocyclic saturated heterocyclyl are aziridinyl, oxiranyl, azetidinyl, oxetanyl, pyrrolidinyl, dimethylpyrrolidinyl, ethoxycarbonylpyrrolidinyl, tetrahydrofuranyl, tetrahydrothienyl, pyrazolidinyl, imidazolidinyl, oxazolidinyl, isoxazolidinyl, thiazolidinyl, piperidinyl, tetrahydropyranyl, tetrahydrothiopyranyl, piperazinyl, morpholinyl, thiomorpholinyl, dioxothiomorpholinyl, azepanyl, diazepanyl, homopiperazinyl or oxazepanyl. The monocyclic saturated heterocyclyl may be further substituted with one to three substituents independently selected from halogen, C _1-6 alkyl and C _1-6 alkoxycarbonyl. Examples of substituted monocyclic saturated heterocyclyl are 4-methylpiperazinyl, dimethylpyrrolidinyl, ethoxycarbonylpyrrolidinyl, difluoropyrrolidinyl, fluoro(methyl)pyrrolidinyl. Examples of bicyclic saturated heterocyclyl are azabicyclo[3.2.1]octyl, quinuclidinyl, oxaazabicyclo[3.2.1]octyl, azabicyclo[3.3.1]nonyl, oxaazabicyclo[3.3.1]nonyl, thiaazabicyclo[3.3.1]nonyl, azaspiro[3.3]heptanyl and oxaazaspiro[3.3]heptanyl. Examples of partially unsaturated heterocyclyl are dihydrofuryl, imidazolinyl, dihydrooxazolyl, tetrahydropyridinyl and dihydropyranyl.

The term "carbonyl" alone or in combination refers to the group -C(O)-.

The term "C _1-6 alkylcarbonyl" refers to the group C _1-6 alkyl-C(O)-, where "C _1-6 alkyl" is as defined above. A special "C _1-6 alkylcarbonyl" group is acetyl.

The term "enantiomer" refers to two stereoisomers of a compound that are not mirror images of each other.

The term "diastereomer" refers to stereoisomers with two or more chiral centers, and their molecules are not mirror images of each other. Diastereomers have different physical properties, such as melting points, boiling points, spectral properties, and reactivities.

The term "pharmaceutically acceptable salts" means salts that are not biologically or otherwise undesirable. Pharmaceutically acceptable salts include both acid addition and base addition salts.

The term "pharmaceutically acceptable acid addition salt" means those pharmaceutically acceptable salts which are formed from inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, carbonic acid, phosphoric acid, and organic acids selected from the classes of aliphatic, cycloaliphatic, aromatic, araliphatic, heterocyclic, carboxylic and sulfonic organic acids such as formic acid, acetic acid, propionic acid, glycolic acid, gluconic acid, lactic acid, pyruvic acid, oxalic acid, malic acid, maleic acid, malonic acid, succinic acid, fumaric acid, tartaric acid, citric acid, aspartic acid, ascorbic acid, glutamic acid, anthranilic acid, benzoic acid, cinnamic acid, mandelic acid, embonic acid, phenylacetic acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid and salicylic acid.

The term "pharmaceutically acceptable base addition salt" means those pharmaceutically acceptable salts that are formed from an organic or inorganic base. Examples of acceptable inorganic bases include the sodium, potassium, ammonium, calcium, magnesium, iron, zinc, copper, manganese, and aluminum salts. Salts derived from pharmaceutically acceptable organic non-toxic bases include salts of primary, secondary and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines and basic ion exchange resins such as isopropylamine, trimethylamine, diethylamine, triethylamine, tripropylamine, ethanolamine, 2-diethylaminoethanol, trimethamine, dicyclohexylamine, lysine, arginine, histidine, caffeine, procaine, hydrabamine, choline, betaine, ethylenediamine, glucosamine, methylglucamine, theobromine, purines, piperazine, piperidine, N-ethylpiperidine and polyamine resins.

The compounds of general formula (I) and their prodrugs, which contain one or more chiral centers, can be presented in the form of either racemates or diastereomeric mixtures, or optically active individual isomers. The racemates can be separated into enantiomers according to known methods. In particular, salts of diastereomers, which can be separated by crystallization, are formed from racemic mixtures as a result of interaction with an optically active acid, such as, for example, D- or L-tartaric acid, mandelic acid, malic acid, lactic acid or camphorsulfonic acid.

The term "prodrug" means a form or derivative of a compound that is metabolized in vivo, such as by the body fluids or enzymes of the subject after administration, into a pharmacologically active form of the compound to produce the desired pharmacological effect. Prodrugs are described, for example, in "The Organic Chemistry of Drug Design and Drug Action", edited by Richard B. Silverman, Academic Press, San Diego, 2004, Chapter 8. Prodrugs and Drug Delivery Systems, pp.497-558.

The term "pharmaceutically active metabolite" is intended to mean a pharmacologically active product formed in the body during the metabolism of a particular compound or its salt. Once in the body, most drugs become substrates for chemical reactions that can change their physical properties and biological effects. Such metabolic transformations, usually affecting the polarity of the compounds of the invention, change the way in which drugs are distributed in and eliminated from the body. However, in some cases, metabolism of the drug is a prerequisite for the manifestation of a therapeutic effect.

The term "therapeutically effective amount" means an amount of a compound or molecule of the present invention that, when administered to a subject, (1) treats or prevents a particular disease, condition, or disorder, (2) alleviates, reduces the intensity of, or eliminates one or more symptoms of a particular disease, condition, or disorder, or (3) prevents or delays the onset of one or more symptoms of a particular disease, condition, or disorder described herein. A therapeutically effective amount will vary depending on the compound, the disease state being treated, the severity of the disease being treated, the age and relative health of the subject, the route and form of administration, the skill of the treating physician or veterinarian, and other factors.

The term "pharmaceutical composition" means a mixture or solution containing a therapeutically effective amount of an active pharmaceutical ingredient together with pharmaceutically acceptable excipients, to be administered to a mammal, such as a human, in need thereof.

TLR7 AGONIST AND PRODRUG

The present invention relates to a compound of formula (I),

Where

R ¹ is C _1-6 alkyl;

R ² is benzyl, wherein said benzyl is unsubstituted or substituted with one, two or three substituents independently selected from halogen and C _1-6 alkyl;

R ³ is -NR ⁴ R ⁵ , where

R ⁴ is C _1-6 alkyl or C _1-6 alkoxyC _1-6 alkyl;

R ⁵ is (C _1-6 alkyl) ₂ NCOOC _1-6 alkyl, C _1-6 alkoxyC _1-6 alkyl, C _1-6 alkoxycarbonyl(C _1-6 alkyl)aminoC _1-6 alkyl, C _1-6 alkoxycarbonyl(phenyl)C _1-6 alkyl, C _1-6 alkoxycarbonylC _1-6 alkyl, C _{1-6 alkyl} alkoxycarbonyloxyC _1-6 alkyl, C _1-6 alkyl, 6alkylcarbonyl(C _1-6 alkyl)aminoC _1-6 alkyl or pyrrolidinylcarbamoyloxyC _1-6 alkyl; or

R ⁴ and R ⁵ together with the nitrogen atom to which they are attached form a heterocyclyl;

or a pharmaceutically acceptable salt, enantiomer or diastereomer thereof; provided that

6-amino-9-benzyl-2-(propylsulfonimidoyl)-7-(pyrrolidine-1-carbonyl)purin-8-one;

6-amino-9-benzyl-7-(piperidine-1-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-7-(morpholine-4-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-7-(3,3-dimethylpyrrolidine-1-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

ethyl 1-[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]pyrrolidine-2-carboxylate;

6-amino-7-(2-azaspiro[3.3]heptane-2-carbonyl)-9-benzyl-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-7-(2-oxa-6-azaspiro[3.3]heptane-6-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-7-(3,3-difluoropyrrolidine-1-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-7-(3-fluoro-3-methyl-pyrrolidine-1-carbonyl)-2-(propylsulfonimidoyl)purin-8-one; and their enantiomers or diastereomers.

A further embodiment of the present invention is (2) a compound of formula (I), wherein

R ¹ is C _1-6 alkyl;

R ² is benzyl, wherein said benzyl is unsubstituted or substituted by halogen and C _1-6 alkyl;

R ³ is azetidinyl;

piperazinyl substituted with C _1-6 alkyl;

piperidinyl substituted with piperidinyl;

pyrrolidinyl;or

-NR ⁴ R ⁵ , where

R ⁴ is C _1-6 alkyl or C _1-6 alkoxyC _1-6 alkyl;

R ⁵ is (C _1-6 alkyl) ₂ NCOOC _1-6 alkyl, C _1-6 alkoxyC _1-6 alkyl, C _1-6 alkoxycarbonyl(C _1-6 alkyl)aminoC _1-6 alkyl, C _1-6 alkoxycarbonyl(phenyl)C _1-6 alkyl, C _1-6 alkoxycarbonylC _1-6 alkyl, C _1-6 alkoxycarbonyloxyC _1-6 alkyl, C _1-6 alkyl, C _1-6 alkylcarbonyl(C _1-6 alkyl)aminoC _1-6 alkyl or pyrrolidinylcarbamoyloxyC _1-6 alkyl; or a pharmaceutically acceptable salt, enantiomer or diastereomer thereof.

A further embodiment of the present invention is (3) a compound of formula (I), wherein

R ¹ represents ethyl or propyl;

R ² represents benzyl, bromobenzyl, chlorobenzyl, fluorobenzyl or methylbenzyl;

R ³ is azetidinyl;

4-methylpiperazinyl;

piperidinylpiperidinyl;

pyrrolidinyl;or

-NR ⁴ R ⁵ , where

R ⁴ represents methyl, ethyl, propyl or methoxyethyl;

R ⁵ is acetyl(methyl)aminoethyl, butyl, butyl(methyl)carbamoyloxyethyl, diethylcarbamoyloxyethyl, ethoxycarbonyl(methyl)aminoethyl, ethoxycarbonylethyl, ethoxycarbonylisobutyl, ethoxycarbonylisopentyl, ethoxycarbonylmethyl, ethoxycarbonyloxyethyl, ethoxycarbonyl(phenyl)ethyl, ethyl, isobutyl, isopropoxycarbonylisopentyl, isopropoxycarbonyl(phenyl)ethyl, isopropyl, methoxycarbonyl(methyl)aminoethyl, methoxyethyl, methoxypropyl, propyl, propyl(methyl)carbamoyloxyethyl, pyrrolidinylcarbamoyloxyethyl, tert-butoxycarbonyl(methyl)aminoethyl, tert-butoxycarbonylethyl, tert-butoxycarbonylisopentyl or tert-butoxycarbonyl(phenyl)ethyl; or a pharmaceutically acceptable salt, enantiomer or diastereomer thereof.

A further embodiment of the present invention is (3-1) a compound of formula (I), wherein

R ¹ represents ethyl or propyl;

R ² represents benzyl, chlorobenzyl, fluorobenzyl or methylbenzyl;

R ³ is azetidinyl;

4-methylpiperazinyl;

piperidinylpiperidinyl;

pyrrolidinyl;or

-NR ⁴ R ⁵ , where

R ⁴ represents methyl, ethyl, propyl or methoxyethyl;

R ⁵ is acetyl(methyl)aminoethyl, butyl, butyl(methyl)carbamoyloxyethyl, diethylcarbamoyloxyethyl, ethoxycarbonyl(methyl)aminoethyl, ethoxycarbonylethyl, ethoxycarbonylisobutyl, ethoxycarbonylisopentyl, ethoxycarbonylmethyl, ethoxycarbonyloxyethyl, ethoxycarbonyl(phenyl)ethyl, ethyl, isobutyl, isopropoxycarbonylisopentyl, isopropoxycarbonyl(phenyl)ethyl, isopropyl, methoxycarbonyl(methyl)aminoethyl, methoxyethyl, methoxypropyl, propyl, propyl(methyl)carbamoyloxyethyl, pyrrolidinylcarbamoyloxyethyl, tert-butoxycarbonyl(methyl)aminoethyl, tert-butoxycarbonylethyl, tert-butoxycarbonylisopentyl or tert-butoxycarbonyl(phenyl)ethyl; or a pharmaceutically acceptable salt, enantiomer or diastereomer thereof.

A further embodiment of the present invention is (4) a compound of formula (I), wherein R ³ is azetidinyl, 4-methylpiperazinyl, piperidinylpiperidinyl, pyrrolidinyl, acetyl(methyl)aminoethyl(methyl)amino, bis(methoxyethyl)amino, butyl(ethyl)amino, butyl(methyl)amino, butyl(methyl)carbamoyloxyethyl(methyl)amino, diethylcarbamoyloxyethyl(methyl)amino, ethoxycarbonyl(methyl)aminoethyl(methyl)amino, ethoxycarbonylethyl(methyl)amino, ethoxycarbonylisobutyl(methyl)amino, ethoxycarbonylisopentyl(methyl)amino, ethoxycarbonylmethyl(methyl)amino, ethoxycarbonyloxyethyl(methyl)amino, ethoxycarbonyl(phenyl)ethyl(methyl)amino, ethyl(methyl)amino, isobutyl(methyl)amino, isopropoxycarbonylisopentyl(methyl)amino, isopropoxycarbonyl(phenyl)ethyl(methyl)amino, isopropyl(methyl)amino, methoxycarbonyl(methyl)aminoethyl(methyl)amino, methoxyethyl(ethyl)amino, methoxyethyl(methyl)amino, methoxyethyl(propyl)amino, methoxypropyl(methyl)amino, propyl(ethyl)amino, propyl(methyl)amino, propyl(methyl)carbamoyloxyethyl(methyl)amino, pyrrolidinylcarbamoyloxyethyl(methyl)amino, tert-butoxycarbonyl(methyl)aminoethyl(methyl)amino, tert-butoxycarbonylethyl(methyl)amino, tert-butoxycarbonylisopentyl(methyl)amino or tert-butoxycarbonyl(phenyl)ethyl(methyl)amino; or a pharmaceutically acceptable salt, enantiomer or diastereomer thereof.

A further embodiment of the present invention is (5) a compound of formula (I) wherein R ¹ is ethyl.

A further embodiment of the present invention is (6) a compound of formula (I) wherein R ² is benzyl substituted with halogen or C _1-6 alkyl.

A further embodiment of the present invention is (7) a compound of formula (I) wherein R ² is bromobenzyl, chlorobenzyl, fluorobenzyl or methylbenzyl.

A further embodiment of the present invention is (7-1) a compound of formula (I) wherein R ² is chlorobenzyl, fluorobenzyl or methylbenzyl.

A further embodiment of the present invention is (8) a compound of formula (I) wherein R ² is bromobenzyl, chlorobenzyl or fluorobenzyl.

A further embodiment of the present invention is (8-1) a compound of formula (I) wherein R ² is chlorobenzyl or fluorobenzyl.

A further embodiment of the present invention is (9) a compound of formula (I), wherein R ³ is -NR ⁴ R ⁵ , wherein R ⁴ is C _1-6 alkyl, R ⁵ is C _1-6 alkyl.

A further embodiment of the present invention is (10) a compound of formula (I) wherein R ³ is propyl(methyl)amino or ethyl(methyl)amino.

A further embodiment of the present invention is (11) a compound of formula (I), wherein

R ¹ is C _1-6 alkyl;

R ² is benzyl, wherein said benzyl is substituted by halogen or C _1-6 alkyl;

R ³ is -NR ⁴ R ⁵ , where R ⁴ is C _1-6 alkyl, R ⁵ is C _1-6 alkyl;

or a pharmaceutically acceptable salt, enantiomer or diastereomer thereof.

A further embodiment of the present invention is (12) a compound of formula (I), wherein

R ¹ represents ethyl;

R ² represents methylbenzyl, bromobenzyl, chlorobenzyl or fluorobenzyl;

R ³ is propyl(methyl)amino or ethyl(methyl)amino; or a pharmaceutically acceptable salt, enantiomer or diastereomer thereof.

A further embodiment of the present invention is (12-1) a compound of formula (I), wherein

R ¹ represents ethyl;

R ² is methylbenzyl, chlorobenzyl or fluorobenzyl;

R ³ represents propyl(methyl)amino or ethyl(methyl)amino;

or a pharmaceutically acceptable salt, enantiomer or diastereomer thereof.

Another embodiment of the present invention is that (13) specific compounds of formula (I) are the following:

6-amino-9-benzyl-N-methyl-8-oxo-N-propyl-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-9-benzyl-N-(2-methoxyethyl)-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-9-benzyl-N-ethyl-8-oxo-N-propyl-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-9-benzyl-7-[4-(1-piperidyl)piperidine-1-carbonyl]-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-N-ethyl-N-(2-methoxyethyl)-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-9-benzyl-N-butyl-N-ethyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-9-benzyl-N-(2-methoxyethyl)-8-oxo-N-propyl-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-9-benzyl-N,N-bis(2-methoxyethyl)-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-7-(azetidine-1-carbonyl)-9-benzyl-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-N-isopropyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-9-benzyl-7-(4-methylpiperazine-1-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-N-(3-methoxypropyl)-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-9-benzyl-N-isobutyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide;

ethyl 2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]acetate;

ethyl 3-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]propanoate;

tert-butyl 3-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]propanoate;

ethyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methyl-amino]propanoate;

tert-butyl-(2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]-4-methyl-pentanoate;

isopropyl-(2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]-4-methyl-pentanoate;

ethyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]-3-methyl-butanoate;

ethyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]-4-methyl-pentanoate;

ethyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methyl-amino]-3-phenyl-propanoate;

isopropyl-(2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]-3-phenylpropanoate;

tert-butyl-(2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]-3-phenylpropanoate;

N-[2-[acetyl(methyl)amino]ethyl]-6-amino-9-benzyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide;

methyl N-[2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl]-N-methyl-carbamate;

tert-butyl N-[2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methyl-amino]ethyl]-N-methyl-carbamate;

ethyl N-[2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl]-N-methyl-carbamate;

2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methyl amino]ethyl N-butyl N-methyl carbamate;

2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl-pyrrolidine-1-carboxylate;

2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methyl amino]ethyl N-methyl N-propyl carbamate;

2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl-N,N-diethylcarbamate;

2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl-ethyl carbonate;

6-amino-N-butyl-9-[(4-chlorophenyl)methyl]-N-methyl-8-oxo-2-[S(S)-propylsulfonimidoyl]purine-7-carboxamide;

6-amino-N-butyl-9-[(4-chlorophenyl)methyl]-N-methyl-8-oxo-2-[S(S)-propylsulfonimidoyl]purine-7-carboxamide;

6-amino-9-[(4-chlorophenyl)methyl]-N-ethyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-N-methyl-8-oxo-N-propyl-2-[S(S)-propylsulfonimidoyl]-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-N-methyl-8-oxo-N-propyl-2-[S(S)-propylsulfonimidoyl]-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-2-[S(S)-propylsulfonimidoyl]-9-(p-tolylmethyl)-7-(pyrrolidine-1-carbonyl)purin-8-one;

6-amino-2-[S(R)-propylsulfonimidoyl]-9-(p-tolylmethyl)-7-(pyrrolidine-1-carbonyl)purin-8-one;

6-amino-N-(2-methoxyethyl)-N-methyl-8-oxo-2-[S(S)-propylsulfonimidoyl]-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-N-(2-methoxyethyl)-N-methyl-8-oxo-2-[S(R)-propylsulfonimidoyl]-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-N-ethyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-N-butyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-9-[(4-chlorophenyl)methyl]-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-9-[(4-chlorophenyl)methyl]-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-9-[(4-chlorophenyl)methyl]-N-ethyl-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-9-[(4-chlorophenyl)methyl]-N-ethyl-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-2-[8(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-N-ethyl-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-N-ethyl-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-2-[S(S)-ethylsulfonimidoyl]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-2-[S(R)-ethylsulfonimidoyl]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-N-ethyl-2-(ethylsulfonimidoyl)-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-N-ethyl-2-[S(S)-(ethylsulfonimidoyl)]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-N-ethyl-2-[S(R)-(ethylsulfonimidoyl)]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-9-[(4-bromophenyl)methyl]-2-(ethylsulfonimidoyl)-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-2-[S(R)-ethylsulfonimidoyl]-9-[(4-bromophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-2-[S(S)-ethylsulfonimidoyl]-9-[(4-bromophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-9-[(4-bromophenyl)methyl]-N-ethyl-2-(ethylsulfonimidoyl)-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-9-[(4-bromophenyl)methyl]-N-ethyl-2-[S(S)-(ethylsulfonimidoyl)]-N-methyl-8-oxo-purine-7-carboxamide; and

6-amino-9-[(4-bromophenyl)methyl]-N-ethyl-2-[S(R)-(ethylsulfonimidoyl)]-N-methyl-8-oxo-purine-7-carboxamide;

or a pharmaceutically acceptable salt, enantiomer or diastereomer thereof.

Another embodiment of the present invention is that (14) more specific compounds of formula (I) are the following:

6-amino-9-benzyl-N-methyl-8-oxo-N-propyl-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-9-[(4-chlorophenyl)methyl]-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-9-[(4-chlorophenyl)methyl]-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-9-[(4-chlorophenyl)methyl]-N-ethyl-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-9-[(4-chlorophenyl)methyl]-N-ethyl-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-N-ethyl-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-N-ethyl-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-9-(l-tolylmethyl)purine-7-carboxamide;

6-amino-2-(ethylsulfonimidoyl)-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-2-[S(S)-ethylsulfonimidoyl]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-2-[S(R)-ethylsulfonimidoyl]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-N-ethyl-2-(ethylsulfonimidoyl)-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-N-ethyl-2-[S(S)-(ethylsulfonimidoyl)]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-N-ethyl-2-[S(R)-(ethylsulfonimidoyl)]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-9-[(4-bromophenyl)methyl]-2-(ethylsulfonimidoyl)-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-2-[S(R)-ethylsulfonimidoyl]-9-[(4-bromophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-2-[S(S)-ethylsulfonimidoyl]-9-[(4-bromophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-9-[(4-bromophenyl)methyl]-N-ethyl-2-(ethylsulfonimidoyl)-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-9-[(4-bromophenyl)methyl]-N-ethyl-2-[S(S)-(ethylsulfonimidoyl)]-N-methyl-8-oxo-purine-7-carboxamide; and

6-amino-9-[(4-bromophenyl)methyl]-N-ethyl-2-[S(R)-(ethylsulfonimidoyl)]-N-methyl-8-oxo-purine-7-carboxamide;

or a pharmaceutically acceptable salt, enantiomer or diastereomer thereof.

In some embodiments, the compounds of the present invention were tested and compared with the following reference compounds. Like most successful biopharmaceutical companies specializing in the discovery and development of TLR7 agonists for the treatment of liver diseases, Gilead has a pipeline of cutting-edge TLR7 agonists, including lead compounds such as GS-962C, which has entered Phase II trials. Gilead's proposed compound GS-962C, disclosed in US 20100143301 as the compound of Example 49, compound S-2, and compound S-3, disclosed in JP 1999193282, were all selected in this application as reference compounds:

SYNTHESIS

The compounds of the present invention may be prepared by any conventional method. Suitable methods for synthesizing these compounds, as well as starting materials for their preparation, are given in the schemes and examples below. All substituents, in particular R ¹ to R ¹⁴ , are as defined above unless otherwise indicated. In addition, and unless otherwise expressly indicated, all reactions, reaction conditions, abbreviations and symbols have the meanings well known to a person of ordinary skill in organic chemistry.

Scheme 1

The compound of formula VI is prepared by cyclization of isocyanate VII using aminomalononitrile p-toluenesulfonate. The bicycle V is then synthesized by reacting the compound of formula VI with benzoyl isothiocyanate in the presence of an inorganic base such as NaOH or KOH. After alkylation of bicycle V with an alkyl halide in the presence of a base such as K ₂ CO ₃ , NaH or Cs ₂ CO ₃ , the compound of formula IV is obtained. The compound of formula III is prepared by oxidation of the compound of formula IV using an oxidizing agent such as meta-chloroperoxybenzoic acid, hydrogen peroxide urea adduct and HIO ₄ . The compound of formula II is prepared by mination of the compound of formula III using an oxidizing reagent such as sodium azide in an acid, wherein said acid is, for example, Eaton's reagent or PPA (polyphosphoric acid). The compound of formula I is prepared by reacting a compound of formula II with carbamoyl chloride in the presence of a mixture of bases such as pyridine and triethylamine, pyridine and DIPEA (N,N-diisopropylethylamine), DMAP (4-dimethylaminopyridine) and triethylamine, or DMAP and DIPEA.

In addition, the compound of formula II can be prepared as in Scheme 2.

A compound of formula X is prepared by reacting a compound of formula XI with R ² NH ₂ . Upon reduction of compound X using a reducing reagent such as zinc or iron powder in AcOH, a compound of formula IX is obtained. Upon cyclization of the compound of formula IX using cyclizing reagents such as phosgene, carbonyldiimidazole, diethyl carbonate and triphosgene, a compound of formula VIII is obtained. A compound of formula IVa is prepared by treating a compound of formula VIII with p-methoxybenzylamine (PMBNH ₂ ). A compound of formula III is prepared by deprotection of a compound of formula IVa using an acid such as CF ₃ COOH, followed by oxidation using an oxidizing agent such as /meta-chloroperoxybenzoic acid, hydrogen peroxide urea adduct and HIO ₄ . The compound of formula II is prepared by the mination of a compound of formula III using an imidizing reagent such as sodium azide in an acid, said acid being, for example, Eaton's reagent or PPA.

The present invention also relates to a process for preparing a compound of formula (I), comprising reacting:

compounds of formula (II)

with carbamoyl chloride in the presence of a mixture of bases;

where R ¹ and R ² are defined above.

In the above step, the mixture of bases can be, for example, pyridine and triethylamine, pyridine and DIPEA, DMAP and triethylamine, or DMAP and DIPEA.

The compound of formula (I) obtained according to the above-mentioned process also forms the subject of the present invention.

PHARMACEUTICAL COMPOSITIONS AND ADMINISTRATION

In another embodiment, there are provided pharmaceutical compositions or medicaments comprising the compounds of the invention and a therapeutically inert carrier, diluent or excipient, as well as methods of using the compounds of the invention for the preparation of such compositions and medicaments. In one example, compositions can be prepared based on the compounds of formula (I) by mixing them at ambient temperature, an appropriate pH and the desired degree of purity with physiologically acceptable carriers, i.e. carriers that are non-toxic to recipients, in dosages and concentrations used in the form of a galenic preparation for administration. The pH of the composition depends mainly on the specific application and concentration of the compound, but preferably varies throughout the range from about 3 to about 8. In one example, a composition is prepared based on a compound of formula (I) in acetate buffer, at pH 5. In another embodiment, the compounds of formula (I) are sterile. The compound can be stored, for example, as a solid or amorphous composition, as a lyophilized composition or as an aqueous solution.

The compositions are prepared, dosed and administered in a manner consistent with good medical practice. Factors considered in this context include the particular disorder being treated, the particular mammal being treated, the clinical condition of the individual patient, the cause of the disorder, the site of delivery of the agent, the route of administration, the schedule of administration and other factors known to physicians. An "effective amount" of the compound to be administered will be guided by such considerations and will be the minimum amount necessary to activate the TLR7 receptor and cause the production of INF-a and other cytokines that can be used, without limitation, to treat or prevent patients with hepatitis B and/or C virus infection.

In one example, a pharmaceutically effective amount of a parenterally administered compound of the invention per dose will be in the range of about 0.1-50 mg/kg, alternatively about 0.1-30 mg/kg of patient body weight per day, with a typical starting range for the compound used being 0.3-15 mg/kg/day. In another embodiment, oral unit dosage forms such as tablets and capsules preferably contain from about 20 to about 1000 mg of a compound of the invention.

The compounds of the invention may be administered by any suitable route, including oral, topical (including buccal and sublingual), rectal, vaginal, transdermal, parenteral, subcutaneous, intraperitoneal, intrapulmonary, intradermal, intrathecal, epidural and intranasal administration, and, if necessary for local treatment, intralesional administration. Parenteral infusions include intramuscular, intravenous, intraarterial, intraperitoneal or subcutaneous administration.

The compounds of the present invention can be administered in any form convenient for administration, for example, in tablets, powders, capsules, solutions, dispersions, suspensions, syrups, sprays, suppositories, gels, emulsions, patches, etc. Such compositions can contain components conventionally used in pharmaceutical preparations, such as diluents, carriers, pH modifiers, sweeteners, bulking agents and other active agents.

A typical composition is prepared by mixing a compound of the present invention and a carrier or excipient. Suitable carriers and excipients are well known to those skilled in the art and are described in detail, for example, in Ansel, Howard C, et al., Ansel's Pharmaceutical Dosage Forms and Drug Delivery Systems. Philadelphia: Lippincott, Williams & Wilkins, 2004; Gennaro, Alfonso R., et al., Remington: The Science and Practice of Pharmacy. Philadelphia: Lippincott, Williams & Wilkins, 2000; and Rowe, Raymond C. Handbook of Pharmaceutical Excipients. Chicago, Pharmaceutical Press, 2005. The compositions may also include one or more of the following: buffers, stabilizing agents, surfactants, wetting agents, lubricants, emulsifiers, suspending agents, preservatives, antioxidants, opacifying agents, glidants, processing aids, colorants, sweeteners, flavors, flavors, diluents, and other known excipients to provide the best presentation of the drug (i.e., the compound of the present invention or a pharmaceutical composition based on it) or to facilitate the production of a pharmaceutical product (i.e., a drug).

An example of a suitable oral dosage form is a tablet containing about 20 to 1000 mg of a compound of the invention in admixture with about 30 to 90 mg of anhydrous lactose, about 5 to 40 mg of sodium croscarmellose, about 5 to 30 mg of polyvinylpyrrolidone (PVP) K30 and about 1 to 10 mg of magnesium stearate. The milled ingredients are first mixed together and then mixed with a solution of PVP. The resulting composition can be dried, granulated, mixed with magnesium stearate and compressed into tablet form using conventional equipment. A typical aerosol composition can be prepared by dissolving a compound of the invention, for example 20 to 1000 mg, in a suitable buffer solution, for example phosphate buffer, adding a tonicity adjusting agent, for example a salt such as sodium chloride, if desired. The solution can be filtered, for example using a filter (0.2 microns), to remove impurities and contaminants.

Thus, one embodiment includes a pharmaceutical composition comprising a compound of formula (I) or its pharmaceutically acceptable salts or their enantiomers or diastereomers.

A further embodiment includes a pharmaceutical composition comprising a compound of formula (I) or its pharmaceutically acceptable salts or enantiomers or diastereomers thereof together with a pharmaceutically acceptable carrier or excipient.

Another embodiment includes a pharmaceutical composition comprising a compound of formula (I) or its pharmaceutically acceptable salts or enantiomers or diastereomers thereof for use in the treatment of hepatitis B virus infection.

INDICATIONS AND TREATMENT METHODS

The present invention provides methods for treating or preventing hepatitis B virus infection and/or hepatitis C virus infection in a patient in need thereof.

The present invention further provides methods for administering a therapeutically effective amount of a compound of formula (I) or other compounds of the invention into the bloodstream of a patient for the treatment and/or prevention of hepatitis B and/or C virus infection.

The methods of the present invention are particularly well suited for human patients. In particular, the methods and doses of the present invention may be useful for, but are not limited to, HBV- and/or HCV-infected patients. The methods and doses of the present invention are also useful for patients undergoing treatment with other antiviral drugs. The methods of prevention of the present invention are particularly useful for patients at risk for viral infection. These patients include, but are not limited to, healthcare workers, such as physicians, nurses, hospice caregivers; military personnel; teachers; child care workers; patients traveling to or residing in foreign countries, particularly in third world countries, including social service workers, missionaries, and foreign diplomats. Finally, the methods and compositions relate to the treatment of difficult-to-treat or non-responsive patients, such as those with resistance to reverse transcriptase inhibitors, protease inhibitors, etc.

Another embodiment includes a method of treating or preventing hepatitis B virus infection and/or hepatitis C virus infection in a mammal in need of such treatment, wherein the method comprises administering to said mammal a therapeutically effective amount of a compound of formula (I) or its enantiomers, diastereomers, prodrugs or pharmaceutically acceptable salts thereof.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1. X-ray diffraction on a single crystal of the compound from Example 41-B.

Fig. 2. X-ray diffraction on a single crystal of the compound from Example 42-A.

Fig. 3. X-ray diffraction on a single crystal of the compound from Example 43-B.

Fig. 4 shows the HBV DNA level, HBsAg level, and anti-HBs antibody level in adeno-associated virus (AAV)-HBV-infected mice treated with the vehicle, the compound of Example 43-A at a dose of 10 mg/kg once every two days (QOD) and once a week (QW) for 42 days. The results are presented as the mean ± SEM (standard error of the mean). LLOQ: lower limit of quantification.

Fig. 5 shows the HBV DNA levels, HBsAg levels, and anti-HBs antibody levels in AAV-HBV-infected mice treated with vehicle, the compound of Example 41-A at 1, 3, 10 mg/kg QOD, and 10 mg/kg QW for 42 days. Results are presented as mean ± SEM. LLOQ: lower limit of quantification.

Fig. 6 shows HBV DNA levels, HBsAg levels, and anti-HBs antibody levels in AAV-HBV-infected mice treated with vehicle, the compound of Example 42-A at 1, 3, and 10 mg/kg QOD for 42 days. Results are presented as mean ± SEM. LLOQ: lower limit of quantification.

Fig. 7 shows HBV DNA levels, HBsAg levels, and anti-HBs antibody levels in AAV-HBV-infected mice treated with vehicle, the compound of Example 41-B at 1, 3, and 10 mg/kg QOD for 42 days. Results are presented as mean ± SEM. LLOQ: lower limit of quantification.

The following are several embodiments of this invention:

1. A compound of formula (I),

Where

R ¹ is C _1-6 alkyl;

R ² is benzyl, wherein said benzyl is unsubstituted or substituted with one, two or three substituents independently selected from halogen and

C _1-6 alkyl;

R ³ is -NR ⁴ R ⁵ , where

R ⁴ is C _1-6 alkyl or C _1-6 alkoxyC _1-6 alkyl;

R ⁵ is (C _1-6 alkyl) ₂ NCOOC _1-6 alkyl, C _1-6 alkoxyC _1-6 alkyl, C _1-6 alkoxycarbonyl(C _1-6 alkyl)aminoC _1-6 alkyl, C _1-6 alkoxycarbonyl(phenyl) _{C 1-6} alkyl, C _1-6 alkoxycarbonyl, C _{1-6 alkyl} alkoxycarbonyloxyC _1-6 alkyl, 6 alkyl, C _1-6 alkylcarbonyl(C _1-6 alkyl) aminoC _1-6 alkyl or pyrrolidinylcarbamoyloxyC _1-6 alkyl; or

R ⁴ and R ⁵ together with the nitrogen atom to which they are attached form a heterocyclyl;

or a pharmaceutically acceptable salt, enantiomer or diastereomer thereof;

provided that excluded

6-amino-9-benzyl-2-(propylsulfonimidoyl)-7-(pyrrolidine-1-carbonyl)purin-8-one;

6-amino-9-benzyl-7-(piperidine-1-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-7-(morpholine-4-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-7-(3,3-dimethylpyrrolidine-1-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

ethyl 1-[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]pyrrolidine-2-carboxylate;

6-amino-7-(2-azaspiro[3.3]heptane-2-carbonyl)-9-benzyl-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-7-(2-oxa-6-azaspiro[3.3]heptane-6-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-7-(3,3-difluoropyrrolidine-1-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-7-(3-fluoro-3-methyl-pyrrolidine-1-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

and their enantiomers or diastereomers.

2. The connection according to item 1, where

R ¹ is C _1-6 alkyl;

R ² is benzyl, wherein said benzyl is unsubstituted or substituted by halogen or C _1-6 alkyl;

R ³ is azetidinyl;

piperazinyl substituted with C _1-6 alkyl;

piperidinyl substituted with piperidinyl;

pyrrolidinyl;or

-NR ⁴ R ⁵ , where

R ⁴ is C _1-6 alkyl or C _1-6 alkoxyC _1-6 alkyl;

R ⁵ is (C _1-6 alkyl) ₂ NCOOC _1-6 alkyl, C _1-6 alkoxyC _1-6 alkyl, C _1-6 alkoxycarbonyl(C _1-6 alkyl)aminoC _1-6 alkyl, C _1-6 alkoxycarbonyl(phenyl)C _1-6 alkyl, C _1-6 alkoxycarbonylC _1-6 alkyl, C _{1-6 alkyl} alkoxycarbonyloxyC _1-6 alkyl, C _1-6 alkyl, C _1-6 alkylcarbonyl(C _1-6 alkyl)aminoC _1-6 alkyl or pyrrolidinylcarbamoyloxyC _1-6 alkyl.

3. The connection according to item 1 or 2, where

R ¹ represents ethyl or propyl;

R ² represents benzyl, bromobenzyl, chlorobenzyl, fluorobenzyl or methylbenzyl;

R ³ is azetidinyl;

4-methylpiperazinyl;

piperidinylpiperidinyl;

pyrrolidinyl; or

-NR ⁴ R ⁵ , where

R ⁴ represents methyl, ethyl, propyl or methoxyethyl;

R ⁵ is acetyl(methyl)aminoethyl, butyl, butyl(methyl)carbamoyloxyethyl, diethylcarbamoyloxyethyl, ethoxycarbonyl(methyl)aminoethyl, ethoxycarbonylethyl, ethoxycarbonylisobutyl, ethoxycarbonylisopentyl, ethoxycarbonylmethyl, ethoxycarbonyloxyethyl, ethoxycarbonyl(phenyl)ethyl, ethyl, isobutyl, isopropoxycarbonylisopentyl, isopropoxycarbonyl(phenyl)ethyl, isopropyl, methoxycarbonyl(methyl)aminoethyl, methoxyethyl, methoxypropyl, propyl, propyl(methyl)carbamoyloxyethyl, pyrrolidinylcarbamoyloxyethyl, tert-butoxycarbonyl(methyl)aminoethyl, tert-butoxycarbonylethyl, tert-butoxycarbonylisopentyl or tert-butoxycarbonyl(phenyl)ethyl.

4. The compound according to claim 3, wherein R ³ is azetidinyl, 4-methylpiperazinyl, piperidinylpiperidinyl, pyrrolidinyl, acetyl(methyl)aminoethyl(methyl)amino, bis(methoxyethyl)amino, butyl(ethyl)amino, butyl(methyl)amino, butyl(methyl)carbamoyloxyethyl(methyl)amino, diethylcarbamoyloxyethyl(methyl)amino, ethoxycarbonyl(methyl)aminoethyl(methyl)amino, ethoxycarbonylethyl(methyl)amino, ethoxycarbonylisobutyl(methyl)amino, ethoxycarbonylisopentyl(methyl)amino, ethoxycarbonylmethyl(methyl)amino, ethoxycarbonyloxyethyl(methyl)amino, ethoxycarbonyl(phenyl)ethyl(methyl)amino, ethyl(methyl)amino, isobutyl(methyl)amino, isopropoxycarbonylisopentyl(methyl)amino, isopropoxycarbonyl(phenyl)ethyl(methyl)amino, isopropyl(methyl)amino, methoxycarbonyl(methyl)aminoethyl(methyl)amino, methoxyethyl(ethyl)amino, methoxyethyl(methyl)amino, methoxyethyl(propyl)amino, methoxypropyl(methyl)amino, propyl(ethyl)amino, propyl(methyl)amino, propyl(methyl)carbamoyloxyethyl(methyl)amino, pyrrolidinylcarbamoyloxyethyl(methyl)amino, tert-butoxycarbonyl(methyl)aminoethyl(methyl)amino, tert-butoxycarbonylethyl(methyl)amino, tert-butoxycarbonylisopentyl(methyl)amino or tert-butoxycarbonyl(phenyl)ethyl(methyl)amino.

5. A compound according to any one of paragraphs 1-4, wherein R ¹ is ethyl.

6. A compound according to claim 1 or 2, wherein R ² is benzyl substituted by halogen or C _1-6 alkyl.

7. A compound according to any one of paragraphs 2-6, wherein R ² is bromobenzyl, chlorobenzyl, fluorobenzyl or methylbenzyl.

8. The compound according to claim 7, wherein R ² is bromobenzyl, chlorobenzyl or fluorobenzyl.

9. The compound according to claim 1 or 2, wherein R ³ is -NR ⁴ R ⁵ , wherein R ⁴ is C _1-6 alkyl, R ⁵ is C _1-6 alkyl.

10. The compound according to claim 9, wherein R ³ is propyl(methyl)amino or ethyl(methyl)amino.

11. A connection according to any of paragraphs 1, 2, 6 and 9, where

R ¹ is C _1-6 alkyl;

R ² is benzyl, wherein said benzyl is substituted by halogen or C _1-6 alkyl;

R ³ is -NR ⁴ R ⁵ , where R ⁴ is C _1-6 alkyl, R ⁵ is C _1-6 alkyl.

12. The connection according to item 11, where

R ¹ represents ethyl;

R ² represents methylbenzyl, bromobenzyl, chlorobenzyl or fluorobenzyl;

R ³ is propyl(methyl)amino or ethyl(methyl)amino.

13. A compound selected from:

6-amino-9-benzyl-N-methyl-8-oxo-N-propyl-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-9-benzyl-N-(2-methoxyethyl)-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-9-benzyl-N-ethyl-8-oxo-N-propyl-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-9-benzyl-7-[4-(1-piperidyl)piperidine-1-carbonyl]-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-N-ethyl-N-(2-methoxyethyl)-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-9-benzyl-N-butyl-N-ethyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-9-benzyl-N-(2-methoxyethyl)-8-oxo-N-propyl-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-9-benzyl-N,N-bis(2-methoxyethyl)-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-7-(azetidine-1-carbonyl)-9-benzyl-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-N-isopropyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-9-benzyl-7-(4-methylpiperazine-1-carbonyl)-2-(propylsulfonimidoyl)purin-8-one;

6-amino-9-benzyl-N-(3-methoxypropyl)-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-9-benzyl-N-isobutyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide;

ethyl 2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]acetate;

ethyl 3-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]propanoate;

tert-butyl 3-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)puri-7-carbonyl]methyl-amino]propanoate;

ethyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methyl-amino]propanoate;

tert-butyl-(2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]-4-methyl-pentanoate;

isopropyl-(2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]-4-methyl-pentanoate;

ethyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7carbonyl]-methyl-amino]-3-methyl-butanoate;

ethyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7carbonyl]-methyl-amino]-4-methyl-pentanoate;

ethyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7carbonyl]-methyl-amino]-3-phenyl-propanoate;

isopropyl-(2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]-3-phenylpropanoate;

tert-butyl-(2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]-3-phenylpropanoate;

N-[2-[acetyl(methyl)amino]ethyl]-6-amino-9-benzyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide;

methyl N-[2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl]-N-methyl-carbamate;

tert-butyl-N-[2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl]-N-methyl-carbamate;

ethyl N-[2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl]-N-methyl-carbamate;

2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonylmethyl-amino]ethyl-N-butyl-N-methyl-carbamate;

2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl-pyrrolidine-1-carboxylate;

2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methyl-amino]ethyl-N-methyl-N-propyl-carbamate;

2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl-N,N-diethylcarbamate;

2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl-ethyl carbonate;

6-amino-N-butyl-9-[(4-chlorophenyl)methyl]-N-methyl-8-oxo-2-[SR)-propylsulfonimidoyl]purine-7-carboxamide;

6-amino-N-butyl-9-[(4-chlorophenyl)methyl]-N-methyl-8-oxo-2-[S(S)-propylsulfonimidoyl]purine-7-carboxamide;

6-amino-9-[(4-chlorophenyl)methyl]-N-ethyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-N-methyl-8-oxo-N-propyl-2-[S(S)-propylsulfonimidoyl]-9-(p-tolylmethyl)purine-7-carboxamide a;

6-amino-N-methyl-8-oxo-N-propyl-2-[S(R)-propylsulfonimidoyl]-9-(p-tolylmethyl)purine-7-carboxamide a;

6-amino-2-[S(S)-propylsulfonimidoyl]-9-(p-tolylmethyl)-7-(pyrrolidine-1-carbonyl)purin-8-one;

6-amino-2-[S(R)-propylsulfonimidoyl]-9-(p-tolylmethyl)-7-(pyrrolidine-1-carbonyl)purin-8-one;

6-amino-N-(2-methoxyethyl)-N-methyl-8-oxo-2-[S(S)-propylsulfonimidoyl]-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-N-(2-methoxyethyl)-N-methyl-8-oxo-2-[SR)-propylsulfonimidoyl]-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-N-ethyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-N-butyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-9-[(4-chlorophenyl)methyl]-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-9-[(4-chlorophenyl)methyl]-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-9-[(4-chlorophenyl)methyl]-N-ethyl-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-9-[(4-chlorophenyl)methyl]-N-ethyl-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-9-(p-tolylmethyl)purine-7-carboxamide a;

6-amino-N-ethyl-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-N-ethyl-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-9-(p-tolylmethyl)purine-7-carboxamide a;

6-amino-2-[S(S)-ethylsulfonimidoyl]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-2-[S(R)-ethylsulfonimidoyl]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-N-ethyl-2-(ethylsulfonimidoyl)-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-N-ethyl-2-[S(S)-(ethylsulfonimidoyl)]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-N-ethyl-2-[S(R)-(ethylsulfonimidoyl)]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-9-[(4-bromophenyl)methyl]-2-(ethylsulfonimidoyl)-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-2-[S(R)-ethylsulfonimidoyl]-9-[(4-bromophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-2-[S(S)-ethylsulfonimidoyl]-9-[(4-bromophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-9-[(4-bromophenyl)methyl]-N-ethyl-2-(ethylsulfonimidoyl)-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-9-[(4-bromophenyl)methyl]-N-ethyl-2-[S(S)-(ethylsulfonimidoyl)]-N-methyl-8-oxo-purine-7-carboxamide; and

6-amino-9-[(4-bromophenyl)methyl]-N-ethyl-2-[S(R)-(ethylsulfonimidoyl)]-N-methyl-8-oxo-purine-7-carboxamide;

or a pharmaceutically acceptable salt, enantiomer or diastereomer thereof.

14. The compound according to item 13, selected from:

6-amino-9-benzyl-N-methyl-8-oxo-N-propyl-2-(propylsulfonimidoyl)purine-7-carboxamide;

6-amino-9-[(4-chlorophenyl)methyl]-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-9-[(4-chlorophenyl)methyl]-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-9-[(4-chlorophenyl)methyl]-N-ethyl-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-9-[(4-chlorophenyl)methyl]-N-ethyl-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-purine-7-carboxamide;

6-amino-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-N-ethyl-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-N-ethyl-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-9-(p-tolylmethyl)purine-7-carboxamide;

6-amino-2-(ethylsulfonimidoyl)-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

6-amino-2-[S(S)-ethylsulfonimidoyl]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide; and

6-amino-2-[S(R)-ethylsulfonimidoyl]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide;

or a pharmaceutically acceptable salt, enantiomer or diastereomer thereof.

15. A method for producing a compound according to any of paragraphs 1-14, comprising the following step:

bringing into reaction a compound of formula (II)

with carbamoyl chloride in the presence of a mixture of bases; wherein the mixture of bases is pyridine and triethylamine, pyridine and DIPEA (diisopropylethylamine), DMAP (4-dimethylaminopyridine) and triethylamine, or DMAP and DIPEA; R ¹ and R ² are as defined in any of paragraphs 1-14.

16. A compound or pharmaceutically acceptable salt, enantiomer or diastereomer according to any one of paragraphs 1-14 for use as a therapeutically active substance.

17. A pharmaceutical composition containing a compound according to any one of paragraphs 1-14 and a therapeutically inert carrier.

18. Use of a compound according to any of paragraphs 1-14 for the treatment or prevention of hepatitis B virus infection.

19. Use of a compound according to any one of paragraphs 1-14 for the preparation of a medicinal product for the treatment or prevention of hepatitis B virus infection.

20. Use of a compound according to any one of claims 1-14 as a Toll-like receptor 7 (TLR7) agonist.

21. Use of a compound according to any one of paragraphs 1-14 for inducing the formation of interferon-α.

22. A compound or pharmaceutically acceptable salt, enantiomer or diastereomer according to any one of paragraphs. 1-14 for the treatment or prevention of hepatitis B virus infection.

23. A compound or pharmaceutically acceptable salt, enantiomer or diastereomer according to any one of paragraphs 1-14, obtained according to the method according to paragraph 15.

24. A method for treating or preventing hepatitis B virus infection, comprising administering a therapeutically effective amount of a compound as defined in any of paragraphs 1-14.

EXAMPLES

The invention will be more fully substantiated with reference to the following examples. However, they should not be construed as limiting the scope of the invention.

ABBREVIATIONS

aq. - water,

BSA - N,O-bis(trimethylsilyl)acetamide,

CDI - N,N'-carbonyl diimidazole,

DIEPA - N,N-diethylpropylamine,

DBU - 1,8-diazabicycloundec-7-ene,

DPPA - diphenylphosphoryl azide,

EC ₅₀ - the molar concentration of an agonist that provides 50% of the maximum possible response to that agonist,

EDC - N1-((ethylimino)methylene)-N3,N3-dimethylpropane-1,3-diamine,

EtOAc or EA - ethyl acetate,

HATU - 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]

pyridinium 3-oxide hexafluorophosphate,

h - hour(s),

HPLC - high performance liquid chromatography,

HOBt: - N-hydroxybenzotriazole,

MS (ESI) - mass spectroscopy (electrospray ionization),

m-CPBA - 3-chloroperbenzoic acid,

MTBE - methyl tert-butyl ether,

NMP - N-methylpyrrolidone,

detected - discovered,

PE - petroleum ether,

RMV - p-methoxybenzyl,

PPA - polyphosphoric acid,

QOD - once every two days,

QW - once a week,

CT or CT - room temperature,

saturated - saturated,

TFA - trifluoroacetic acid,

TEA - triethylamine,

v/v - volume ratio.

GENERAL EXPERIMENTAL CONDITIONS

The intermediates and final compounds were purified by flash chromatography using one of the following instruments: 1) SP1 system and Quad 12/25 cartridge module from Biotage; 2) Combi flash chromatography instrument from ISCO. Silica gel grade and pore size: 1) KP-SIL 60 A, particle size: 40-60 μm; 2) CAS (Chemical Abstracts Service) Registry No.: Silica Gel: 63231-67-4, silica gel particle size: 47-60 μm; 3) ZCX from Qingdao Haiyang Chemical Co., Ltd; pore size: 200-300 or 300-400.

Intermediates and final compounds were purified by preparative HPLC on a reversed-phase column using an XBridge™ preparative C ₁₈ column (5 μm, OBD™ 30×100 mm) or a SunFire™ preparative C ₁₈ column (5 μm, OBD™ 30×100 mm).

LC/MS spectra were obtained using a Waters single quadrupole ultra-performance liquid chromatography (UPLC) mass detector (SQD). The following standard LC/MS conditions were used (run time 3 min).

Acidic conditions: A: 0.1% formic acid and 1% acetonitrile in _H2O ; B: 0.1% formic acid in acetonitrile;

basic conditions: A: 0.05% _NH3⋅H2O in _H2O ; B _: acetonitrile.

Mass spectra (MS): Generally only values for ions corresponding to the reference mass are reported and, unless otherwise stated, the reported ion mass is the mass of the positively charged ion (M+H) ⁺ .

Nuclear magnetic resonance (NMR) spectra were obtained using a Bruker Avance 400 MHz instrument.

All reactions involving air-sensitive reagents were performed under argon. Reagents were used as received from commercial suppliers without further purification unless otherwise stated.

PREPARATORY EXAMPLES

Obtaining intermediate compounds

Intermediate compound AA

N-Methyl-N-propyl-carbamoyl chloride

To a mixture of N-methylpropan-1-amine (5 g; 68.4 mmol) and sodium hydrogen carbonate (11.5 g; 137 mmol) in dichloromethane (DCM) (70 ml) at 0 °C was added dropwise bis(trichloromethyl)carbonate (8.11 g; 27.3 mmol) in DCM (30 ml). The mixture was stirred at room temperature for 2 h and filtered. The filtrate was concentrated in vacuo. The resulting N-methyl-N-propylcarbamoyl chloride (7.2 g; intermediate AA) was used in the next step without further purification.

Intermediate connection AB

N-(2-Methoxyethyl)-N-methylcarbamoyl chloride

Intermediate AB was prepared in analogy to intermediate AA, using 2-methoxy-N-methylethanamine instead of N-methylpropan-1-amine. N-(2-methoxyethyl)-N-methylcarbamoyl chloride (8 g; intermediate AB) was obtained and used in the next step without further purification.

Intermediate connection AC

N-Ethyl-N-propyl-carbamoyl chloride

Intermediate AC was prepared in analogy to intermediate AA, using N-ethylpropan-1-amine instead of N-methylpropan-1-amine. N-Ethyl-N-propylcarbamoyl chloride (12.6 g; intermediate AC) was obtained as a yellow oil and used in the next step without further purification.

AD Intermediate Connection

N-Ethyl-N-(2-methoxyethyl)carbamoyl chloride

Intermediate AD was prepared in analogy to intermediate AA, using N-ethyl-2-methoxyethanamine instead of N-methylpropan-1-amine. Crude N-ethyl-N-(2-methoxyethyl)carbamoyl chloride (2.5 g; intermediate AD) was obtained as a light yellow oil and was used in the next step without further purification.

Intermediate connection AE

N-Butyl-N-ethyl-carbamoyl chloride

Intermediate AE was prepared in analogy to intermediate AA, using N-ethylbutan-1-amine (5 g) instead of N-methylpropan-1-amine. Crude N-butyl-N-ethylcarbamoyl chloride (6.3 g; intermediate AE) was obtained as a light yellow oil and was used in the next step without further purification.

AF Intermediate Connection

N-(2-Methoxyethyl)-N-propyl-carbamoyl chloride

Intermediate AF was prepared in analogy to intermediate AA, using N-(2-methoxyethyl)propan-1-amine (2 g, 17.1 mmol) instead of N-methylpropan-1-amine. Crude N-(2-methoxyethyl)-N-propylcarbamoyl chloride (2.5 g; intermediate AF) was obtained as a light yellow oil and used in the next step without further purification.

Intermediate connection AG

N,N-Bis(2-methoxyethyl)carbamoyl chloride

Intermediate AG was prepared in analogy to intermediate AA, using bis(2-methoxyethyl)amine (2 g; 15 mmol) instead of N-methylpropan-1-amine. The crude product N,N-bis(2-methoxyethyl)carbamoyl chloride (2.6 g; intermediate AG) was obtained as a light yellow oil and was used in the next step without further purification.

Intermediate connection AN

Azetidine-1-carbonyl chloride

Intermediate AN was prepared in analogy to intermediate AA using azetidine hydrochloride (10.7 g, 107 mmol) and sodium bicarbonate (3 equiv) instead of N-methylpropan-1-amine and sodium bicarbonate (2 equiv). Crude azetidine-1-carbonyl chloride (1.5 g; intermediate AN) was obtained as a light yellow oil and was used in the next step without further purification.

Intermediate AI connection

N-Isopropyl-N-methyl-carbamoyl chloride

Intermediate AI was prepared in analogy to intermediate AA, using N-methylpropan-2-amine (5 g; 19.4 mmol) instead of N-methylpropan-1-amine. Crude N-isopropyl-N-methylcarbamoyl chloride (8.6 g; intermediate AI) was obtained as a yellow oil and was used in the next step without further purification.

Intermediate connection AL

N-Isobutyl-N-methyl-carbamoyl chloride

Intermediate AL was prepared in analogy to intermediate AA, using N-2-dimethylpropan-1-amine (4.8 g) instead of N-methylpropan-1-amine. Crude N-isobutyl-N-methylcarbamoyl chloride (8.1 g; intermediate AL) was obtained as a light yellow oil and was used in the next step without further purification.

Intermediate connection AP

Ethyl 2-[chlorocarbonyl(methyl)amino]acetate

To a solution of triphosgene (728 mg, 2.45 mmol) in DCM (5 ml) was added dropwise at 0 °C a solution of ethyl 2-(methylamino)acetate hydrochloride (1.3 g, 8.46 mmol) and pyridine (1 ml) in DCM (5 ml). The reaction mixture turned orange and a yellow precipitate appeared, then the mixture was allowed to warm to room temperature. After stirring for 1 h, an aqueous HCl solution (0.1 N, 25 ml) was added to the reaction mixture, the organic layer was separated, washed twice with 0.1 N HCl and 100 mL of ethyl acetate. HCl solution (10 ml), brine (10 ml), dried over Na ₂ SO ₄ and concentrated in vacuo to give crude ethyl 2-[chlorocarbonyl(methyl)amino]acetate (2.0 g; intermediate AP) as a light yellow oil, which was used in the next step without further purification.

Intermediate AR connection

tert-Butyl 3-[chlorocarbonyl(methyl)amino]propanoate

Step 1. Obtaining tert-butyl 3-(methylamino)propanoate (compound AR-1)

To a solution of tert-butyl acrylate (3 g) in dimethylformamide (DMF) (40 mL) at -45 °C were added methylamine hydrochloride (4.74 g, 70 mmol) and DBU (21.4 g, 140 mmol). Then, the temperature of the reaction mixture was raised to -10 °C. The reaction mixture was stirred at the same temperature for 2.5 h. Et ₂ O (200 mL) was added and the resulting mixture was washed four times with brine (50 mL). The separated organic layer was dried over Na ₂ SO ₄ and concentrated in vacuo to give tert-butyl 3-(methylamino)propanoate (3.5 g; compound AR-1) as a light yellow oil.

Step 2. Preparation of tert-butyl 3-[chlorocarbonyl(methyl)amino]propanoate (intermediate AR)

Intermediate AR was prepared in analogy to intermediate AR using tert-butyl 3-(methylamino)propanoate (3.4 g; compound AR-1) instead of ethyl 2-(methylamino)acetate hydrochloride. Crude tert-butyl 3-[chlorocarbonyl(methyl)amino]propanoate (3.5 g; intermediate AR) was obtained and used in the next step without further purification.

Intermediate connection AS

Ethyl (2S)-2-[chlorocarbonyl (methyl) amino] propanoate

Step 1. Obtaining ethyl (2S)-2-(methylamino)propanoate hydrochloride (compound AS-1)

To a solution of (2S)-2-(methylamino)propanoic acid (1 g, 9.70 mmol) in EtOH (10 mL) was added dropwise at 0 °C over 0.5 h. The reaction mixture was stirred at ₂₅ °C for 15.5 h, then diluted with EA (20 mL), washed with H ₂ O (5 mL) and brine (5 mL). The organic layer was dried over Na ₂ SO ₄ and concentrated in vacuo. Ethyl (2S)-2-(methylamino)propanoate hydrochloride (1.8 g; compound AS-1) was obtained as a yellow oil and used in the next step without further purification.

Step 2. Obtaining ethyl (2S)-2-(methylamino)propanoate (compound AS-2)

The pH of a solution of ethyl (2S)-2-(methylamino)propanoate hydrochloride (1.8 g; compound AS-1) in EA (10 mL) was adjusted to 8 using 10 wt % aqueous NaHCO ₃ solution. The reaction mixture was stirred at room temperature for 0.5 h. The organic layer was washed with brine (5 mL), dried over Na ₂ SO ₄ and concentrated in vacuo. Ethyl (2S)-2-(methylamino)propanoate (620 mg; compound AS-2) was obtained as a yellow oil and used in the next step without further purification.

Step 3. Preparation of ethyl (2S)-2-[chlorocarbonyl(methyl)amino]propanoate (intermediate AS)

Intermediate AS was prepared in analogy to intermediate AP using ethyl (2S)-2-(methylamino)propanoate (260 mg; AS-2) instead of ethyl 2-(methylamino)acetate hydrochloride. Crude ethyl (2S)-2-[chlorocarbonyl(methyl)amino]propanoate (200 mg; intermediate AS) was obtained as a yellow oil and was used in the next step without further purification.

AT Intermediate Connection

tert-Butyl (2S)-2-[chlorocarbonyl (methyl) amino]-4-methyl pentanoate

Stage 1. Obtaining tert-butyl (2S)-4-methyl-2-(methylamino)pentanoate (compound AT-1)

2-Methylpropene (25 g, 446 mmol) was bubbled through DCM (50 mL) at -78 °C. Then, to a solution of (S)-4-methyl-2-(methylamino)pentanoic acid hydrochloride (500 mg, 2.75 mmol) and H ₂ SO ₄ (3.68 g, 2 mL, 37.5 mmol) in dioxane (20 mL) at 0 °C was added the solution of 2-methylpropene. The reaction mixture was stirred at room temperature for 18 h in a sealed tube. The reaction solution was poured into ice-cold aqueous KOH solution (8.4 g in water (30 mL)) and the resulting mixture was extracted twice with DCM (50 mL). The combined organic layer was washed twice with brine (30 mL), dried over Na ₂ SO ₄ and concentrated in vacuo to give the crude product, tert-butyl (2S)-4-methyl-2-(methylamino)pentanoate (compound AT-1), as a light yellow oil.

Step 2. Preparation of tert-butyl (2S)-2-[chlorocarbonyl(methyl)amino]-4-methylpentanoate (intermediate AT)

Intermediate AT was prepared in analogy to intermediate AP, using tert-butyl (2S)-4-methyl-2-(methylamino)pentanoate (300 mg; compound AT-1) instead of ethyl 2-(methylamino)acetate hydrochloride. Crude tert-butyl (2S)-2-[chlorocarbonyl(methyl)amino]-4-methylpentanoate (350 mg; intermediate AT) was obtained as a light yellow oil and was used in the next step without further purification.

Intermediate connection AU

Isopropyl (2S)-2-[chlorocarbonyl(methyl)amino]-4-methylpentanoate

Step 1. Preparation of isopropyl (2S)-4-methyl-2-(methylamino)pentanoate hydrochloride (compound AU-1)

To a solution of (S)-4-methyl-2-(methylamino)pentanoic acid hydrochloride (0.5 g) in i-PrOH (7.8 g, 10 mL) was added dropwise thionyl chloride (655 mg, 402 μL) at room temperature. The resulting mixture was stirred and refluxed for 16 h and then concentrated in vacuo. The residue was basified with saturated aqueous NaHCO ₃ (30 mL) and extracted with DCM (50 mL). The organic layer was washed with brine, dried over Na ₂ SO ₄ and concentrated in vacuo. The residue was salified using HCl/EtOAc (10 mL, 1 mmol/mL) and concentrated to give isopropyl (2S)-4-methyl-2-(methylamino)pentanoate hydrochloride (510 mg; Compound AU-1) as a white solid.

Step 2. Preparation of isopropyl (2S)-2-[chlorocarbonyl(methyl)amino]-4-methylpentanoate (intermediate AU)

Intermediate AU was prepared in analogy to intermediate AP, using isopropyl (2S)-4-methyl-2-(methylamino)pentanoate hydrochloride (500 mg; compound AU-1) instead of ethyl 2-(methylamino)acetate hydrochloride. Crude isopropyl (2S)-2-[chlorocarbonyl(methyl)amino]-4-methylpentanoate (650 mg; intermediate AU) was obtained as a light yellow oil and was used in the next step without further purification.

AV Intermediate Connection

Ethyl (2S)-2-[chlorocarbonyl(methyl)amino]-3-methyl-butanoate

Step 1. Obtaining ethyl (2S)-3-methyl-2-(methylamino)butanoate hydrochloride (compound AV-1)

To a solution of (2S)-3-methyl-2-(methylamino)butanoic acid (1.0 g, 7.6 mmol) in EtOH (10 mL) was added dropwise at room temperature. The resulting mixture was stirred and refluxed for 16 h and then concentrated in vacuo. The residue was basified with saturated aqueous NaHCO ₃ (30 mL) and extracted twice with DCM (50 mL). The combined organic layer was washed with brine, dried over Na ₂ SO ₄ and concentrated in vacuo. The residue was dissolved in HCl/EtOAc (10 mL, 1 M) and concentrated to give ethyl (2S)-3-methyl-2-(methylamino)butanoate hydrochloride (1.9 g; compound AV-1) as a white solid.

Step 2. Preparation of ethyl (2S)-2-[chlorocarbonyl(methyl)amino]-3-methyl-butanoate (intermediate compound AV)

Intermediate AV was prepared in analogy to intermediate AP, using ethyl (2S)-3-methyl-2-(methylamino)butanoate hydrochloride (500 mg; compound AV-1) instead of ethyl 2-(methylamino)acetate hydrochloride. Crude ethyl (2S)-2-[chlorocarbonyl (methyl)amino]-3-methylbutanoate (600 mg; intermediate AV) was obtained as a light yellow oil and was used in the next step without further purification.

Intermediate connection AW

Ethyl (2S)-2-[chlorocarbonyl(methyl)amino]-4-methylpentanoate

Step 1. Preparation of ethyl (2S)-4-methyl-2-(methylamino)pentanoate hydrochloride (compound AW-1)

To a solution of (2S)-4-methyl-2-(methylamino)pentanoic acid (1 g, 6.9 mmol) in EtOH (10 mL) was added dropwise at room temperature. The resulting mixture was stirred at reflux for 16 h and then concentrated in vacuo. The residue was basified with saturated aqueous NaHCO ₃ (30 mL) and extracted with DCM (50 mL). The organic layer was washed with brine, dried over Na ₂ SO ₄ and concentrated in vacuo. The residue was salified with HCl/EtOAc (10 mL, 1 mmol/mL) and concentrated to give ethyl (2S)-4-methyl-2-(methylamino)pentanoate hydrochloride (1.8 g; compound AW-1) as a white solid.

Step 2. Preparation of ethyl (2S)-2-[chlorocarbonyl(methyl)amino]-4-methylpentanoate (intermediate AW)

Intermediate AW was prepared in analogy to intermediate AP, using ethyl (2S)-4-methyl-2-(methylamino)pentanoate hydrochloride (610 mg; AW-1) instead of ethyl 2-(methylamino)acetate hydrochloride. Crude ethyl (2S)-2-[chlorocarbonyl(methyl)amino]-4-methylpentanoate (280 mg; intermediate AW) was obtained as a light yellow oil and was used in the next step without further purification.

Intermediate connection AX

Ethyl (2S)-2-[chlorocarbonyl(methyl)amino]-3-phenylpropanoate

Chiral

Intermediate AX was prepared in analogy to intermediate AP using (S)-ethyl 2-(methylamino)-3-phenylpropanoate instead of ethyl 2-(methylamino)acetate hydrochloride. Crude ethyl (2S)-2-[chlorocarbonyl(methyl)amino]-3-phenylpropanoate (200 mg; intermediate AX) was obtained as a light yellow oil and was used in the next step without further purification.

Intermediate connection AY

Isopropyl-(2S)-2-[chlorocarbonyl(methyl)amino]-3-phenylpropanoate

Intermediate AY was prepared in analogy to intermediate AP, using isopropyl (2S)-2-(methylamino)-3-phenylpropanoate (190 mg) instead of ethyl 2-(methylamino)acetate hydrochloride. Crude isopropyl (2S)-2-[chlorocarbonyl(methyl)amino]-3-phenylpropanoate (220 mg; intermediate AY) was obtained as a light brown oil and was used in the next step without further purification.

Intermediate connection AZ

(S)-tert-Butyl-2-((chlorocarbonyl)(methyl)amino)-3-phenylpropanoate

Step 1. Obtaining tert-butyl (2S)-2-(methylamino)-3-phenylpropanoate (compound AZ-1)

2-Methylpropene (25 g, 446 mmol) was bubbled through DCM (50 mL) at -78 °C. Then, to a solution of (S)-2-(methylamino)-3-phenylpropanoic acid (500 mg) and H ₂ SO ₄ (3.68 g, 2 mL) in dioxane (20 mL) at 0 °C was added the 2-methylpropene solution. The reaction mixture was stirred at room temperature for 18 h in a sealed tube. The reaction mixture was poured into ice-cold aqueous KOH (8.4 g in water (30 mL)) and the resulting mixture was extracted twice with DCM (50 mL). The organic layer was washed twice with brine (30 mL), dried over Na ₂ SO ₄ and concentrated in vacuo to give tert-butyl (2S)-2-(methylamino)-3-phenylpropanoate (710 mg; compound AZ-1) as a light yellow oil.

Step 2. Preparation of (S)-tert-butyl 2-((chlorocarbonyl)(methyl)amino)-3-phenylpropanoate (intermediate AZ)

Intermediate AZ was prepared in analogy to intermediate AP, using tert-butyl (2S)-2-(methylamino)-3-phenylpropanoate (compound AZ-1) instead of ethyl 2-(methylamino)acetate hydrochloride. Crude tert-butyl (2S)-2-[chlorocarbonyl(methyl)amino]-3-phenylpropanoate (360 mg; intermediate AZ) was obtained as a light yellow oil and was used in the next step without further purification.

Intermediate connection VA

N-[2-[Acetyl(methyl)amino]ethyl]-N-methylcarbamoyl chloride

Stage 1. Obtaining tert-butyl N-[2-[acetyl(methyl)amino]ethyl]-N-methyl-carbamate (compound BA-1)

To a solution of tert-butyl methyl (2-(methylamino)ethyl)carbamate (1.13 g, 6 mmol) in pyridine (10 mL) was added dropwise at 0 °C. The solution was then stirred at room temperature for 0.5 h. The solvent was removed in vacuo and the residue was partitioned between EtOAc (50 mL) and saturated aqueous NaHCO ₃ (25 mL). The organic layer was separated, washed with brine (20 mL), dried over Na ₂ SO ₄ and concentrated in vacuo to give tert-butyl N-[2-[acetyl(methyl)amino]ethyl]-N-methylcarbamate (1.28 g; compound BA-1) as a yellow oil.

Step 2. Obtaining N-methyl-N-(2-(methylamino)ethyl)acetamide hydrochloride (compound BA-2)

A mixture of tert-butyl N-[2-[acetyl(methyl)amino]ethyl]-N-methyl carbamate (1.1 g; Compound BA-1) in HCl/EtOAc (10 mL; 1 N HCl in EtOAc) was stirred at room temperature for 2 h, then the mixture was filtered. The collected solid was washed three times with EtOAc (5 mL) and dried in vacuo to give crude N-methyl-N-(2-(methylamino)ethyl)acetamide hydrochloride (460 mg; Compound BA-2) as a white solid.

Step 3. Preparation of N-[2-[acetyl(methyl)amino]ethyl]-N-methylcarbamoyl chloride (intermediate BA)

Intermediate BA was prepared in analogy to intermediate AP, using N-methyl-N-(2-(methylamino)ethyl)acetamide hydrochloride (200 mg; compound BA-2) instead of ethyl 2-(methylamino)acetate hydrochloride. Crude N-[2-[acetyl(methyl)amino]ethyl]-N-methylcarbamoyl chloride (300 mg; intermediate BA) was obtained and used in the next step without further purification.

Intermediate connection BB

Methyl N-[2-[chlorocarbonyl(methyl)amino]ethyl]-N-methyl carbamate

Stage 1. Obtaining methyl N-methyl-N-[2-(methylamino)ethyl]carbamate (compound BB-1)

To a solution of N,N'-dimethylethane-1,2-diamine (10 g) in THF (40 ml) was added dropwise at -70 °C over 1 h. The mixture was stirred at 25 °C for 15 h, then filtered and washed with water and brine. The organic layer was dried and concentrated to give a yellow residue, which was purified by column chromatography to give methyl N-methyl-N-[2-(methylamino)ethyl]carbamate (2 g; compound BB-1) as a colorless oil.

Step 2. Preparation of methyl N-[2-[chlorocarbonyl(methyl)amino]ethyl]-N-methyl-carbamate (intermediate BB)

Intermediate BB was prepared in analogy to intermediate AP, using methyl N-methyl-N-[2-(methylamino)ethyl]carbamate (2.0 g; compound BB-1) instead of ethyl 2-(methylamino)acetate hydrochloride. Crude methyl N-[2-[chlorocarbonyl(methyl)amino]ethyl]-N-methylcarbamate (2.2 g; intermediate BB) was obtained and used in the next step without further purification.

Intermediate connection of the aircraft

tert-Butyl-N-[2-[chlorocarbonyl(methyl)amino]ethyl]-N-methyl-carbamate

Stage 1. Obtaining tert-butyl-N-methyl-N-[2-(methylamino)ethyl]carbamate (compound BC-1)

To a solution of N,N'-dimethylethane-1,2-diamine (40.4 g) in DCM (300 mL) was added dropwise at 0 °C over 1 h. The reaction mixture was stirred at room temperature for 18 h. The organic layer was washed with saturated aqueous NaHCO ₃ solution (50 mL), brine (50 mL), dried over _{Na 2 SO 4} and concentrated in vacuo. The residue was purified by column chromatography to give tert-butyl N-methyl N-[2-(methylamino)ethyl]carbamate (6.8 g; compound BC-1) as a yellow oil. ¹ H-NMR (400 MHz, CDCl ₃ ) δ ^ppm : 3.34 (br. s., 2H), 2.89 (s, 3H), 2.74 (t, J=6.7 Hz, 2H), 2.46 (s, 3H), 1.47 (s, 9H).

Step 2. Preparation of tert-butyl N-[2-[chlorocarbonyl(methyl)amino]-ethyl]-N-methyl-carbamate (intermediate BC)

Intermediate BC was prepared in analogy to intermediate AP, using tert-butyl N-methyl N-[2-(methylamino)ethyl]carbamate (1.15 g; compound BC-1) instead of ethyl 2-(methylamino)acetate hydrochloride. Crude tert-butyl N-[2-[chlorocarbonyl(methyl)amino]ethyl]-N-methylcarbamate (1.3 g; intermediate BC) was obtained and used in the next step without further purification.

Intermediate BD

Ethyl N-[2-[chlorocarbonyl(methyl)amino]ethyl]-N-methyl-carbamate

Step 1. Preparation of ethyl N-methyl N-[2-(methylamino)ethyl]carbamate (compound BD-1)

To a solution of N,N'-dimethylethane-1,2-diamine (10 g) in DCM (40 mL) was added dropwise at -70 °C over 1 h. The reaction mixture was stirred at 25 °C for 15 h, then filtered and washed with water and brine. The organic layer was dried and concentrated in vacuo. The yellow residue was purified by column chromatography to give ethyl N-methyl-N-[2-(methylamino)ethyl]carbamate (2 g; compound BD-1) as a colorless oil.

Step 2. Preparation of ethyl N-[2-[chlorocarbonyl(methyl)amino]ethyl]-N-methyl-carbamate (intermediate BD)

Intermediate BD was prepared in analogy to intermediate AA, using ethyl N-methyl N-[2-(methylamino)ethyl]carbamate (compound BD-1) instead of ethyl 2-(methylamino)acetate hydrochloride. Crude ethyl N-[2-[chlorocarbonyl(methyl)amino]ethyl]-N-methylcarbamate (2.2 g; intermediate BD) was obtained and used in the next step without further purification.

Intermediate connection BE

2-[Chlorocarbonyl(methyl)amino]ethyl-N-butyl-N-methyl-carbamate

Step 1. Obtaining tert-butyl-N-(2-hydroxyethyl)-N-methyl-carbamate (compound BE-1)

To a solution of 2-(methylamino)ethanol (10 g, 133.14 mmol) in DCM (10 ml) was added Boc ₂ O (34.87 g, 159.77 mmol) at 25 °C. The mixture was stirred at 25 °C for 16 h and then concentrated. The residue was purified by column chromatography to give tert-butyl N-(2-hydroxyethyl)-N-methyl carbamate (20 g; compound BE-1) as a colorless oil.

Step 2. Obtaining 2-[tert-butoxycarbonyl(methyl)amino]ethyl-N-butyl-N-methyl-carbamate (compound BE-2)

To a solution of tert-butyl N-(2-hydroxyethyl)-N-methyl-carbamate (880 mg; Compound BE-1) and _Et3N (1 g; 10.08 mmol) in DCM (10 mL) was added dropwise at -10 °C over 1 h. The reaction mixture was stirred at 25 °C for 15 h, then filtered and washed with water and brine. The organic layer was dried and concentrated to give 2-[tert-butoxycarbonyl(methyl)amino]ethyl N-butyl-N-methyl-carbamate (2 g; Compound BE-2) as a colorless oil.

Step 3. Obtaining 2-(methylamino)ethyl-N-butyl-N-methyl-carbamate hydrochloride (compound BE-3)

To a solution of 2-[tert-butoxycarbonyl(methyl)amino]ethyl N-butyl N-methyl carbamate (1 g; Compound BE-2) was added HCl/EA (40 mL; 1 M). The reaction mixture was stirred at 0 °C for 0.5 h, warmed to 25 °C and stirred for an additional 15.5 h. The reaction mixture was concentrated to give 2-(methylamino)ethyl N-butyl N-methyl carbamate hydrochloride (400 mg; Compound BE-3) as a colorless oil.

Step 4. Preparation of 2-[chlorocarbonyl(methyl)amino]ethyl N-butyl N-methyl carbamate (intermediate BE)

Intermediate BE was prepared in analogy to intermediate AP, using 2-(methylamino)ethyl N-butyl N-methylcarbamate hydrochloride (374 mg; compound BE-3) instead of ethyl 2-(methylamino)acetate hydrochloride. Crude 2-[chlorocarbonyl(methyl)amino]ethyl N-butyl N-methylcarbamate (330 mg; intermediate BE) was obtained and used in the next step without further purification.

Intermediate connection BF

2-[Chlorocarbonyl(methyl)amino]ethyl-pyrrolidine-1-carboxylate

Step 1. Preparation of tert-butyl N-(2-hydroxyethyl)-N-methyl carbamate (compound BF-1)

To a solution of 2-(methylamino)ethanol (10 g, 133.14 mmol) in DCM (10 ml) was added Boc ₂ O (34.87 g, 159.77 mmol) at 25 °C. The mixture was stirred at 25 °C for 16 h. The reaction mixture was concentrated to give a residue, which was purified by column chromatography to give tert-butyl N-(2-hydroxyethyl)-N-methyl carbamate (20 g; compound BF-1) as a colorless oil.

Step 2. Preparation of 2-[tert-butoxycarbonyl(methyl)amino]ethyl pyrrolidine-1-carboxylate (compound BF-2)

To a solution of tert-butyl N-(2-hydroxyethyl)-N-methyl carbamate (300 mg, 1.71 mmol; Compound BF-1) and _Et3N (578 mg, 5.71 mmol) in DCM (5 mL) was added dropwise at 0 °C over 0.5 h, pyrrolidine-1-carbonyl chloride (458 mg, 3.4 mmol), which was then stirred at 25 °C for 15.5 h. After filtration, the filtrate was washed with water and brine. The organic layer was dried and concentrated to give 2-[tert-butoxycarbonyl(methyl)amino]ethyl pyrrolidine-1-carboxylate (335 mg; Compound BF-2) as a colorless oil.

Step 3. Preparation of 2-(methylamino)ethyl-pyrrolidine-1-carboxylate hydrochloride (compound BF-3)

2-[tert-Butoxycarbonyl(methyl)amino]ethyl pyrrolidine-1-carboxylate (335 mg; Compound BF-2) was added to a solution of HCl in EA (12.3 ml; 1 M), and the mixture was stirred at 0°C for 0.5 h and then at 25°C for another 15.5 h. The reaction mixture was concentrated to give 2-(methylamino)ethyl pyrrolidine-1-carboxylate hydrochloride (300 mg; Compound BF-3) as a colorless oil.

Step 4. Preparation of 2-[chlorocarbonyl(methyl)amino]ethyl pyrrolidine-1-carboxylate (intermediate BF)

Intermediate BF was prepared in analogy to intermediate AP, using 2-(methylamino)ethyl pyrrolidine-1-carboxylate hydrochloride (299 mg; compound BF-3) instead of ethyl 2-(methylamino)acetate hydrochloride. Crude 2-[chlorocarbonyl(methyl)amino]ethyl pyrrolidine-1-carboxylate (230 mg; intermediate BF) was obtained and used in the next step without further purification.

Intermediate connection BG

2-[Chlorocarbonyl(methyl)amino]ethyl-N-methyl-N-propyl-carbamate

Step 1. Preparation of tert-butyl N-(2-hydroxyethyl)-N-methyl carbamate (compound BG-1)

To a solution of 2-(methylamino)ethanol (10 g, 133.14 mmol) in DCM (10 mL) was added Boc ₂ O (34.87 g, 159.77 mmol) at 25 °C. The reaction mixture was stirred at 25 °C for 16 h, then concentrated to give a residue, which was purified by column chromatography to give tert-butyl N-(2-hydroxyethyl)-N-methyl carbamate (20 g; compound BG-1) as a colorless oil.

Step 2. Preparation of tert-butyl N-methyl N-[2-[methyl(propyl)carbamoyl]oxyethyl]carbamate (compound BG-2)

To a solution of tert-butyl N-(2-hydroxyethyl)-N-methylcarbamate (265 mg; Compound BG-1) and _Et3N (1 mL; 5.71 mmol) in DCM (5 mL) was added N-methyl-N-propylcarbamoyl chloride (410 mg; 1.83 mmol) dropwise at 0 °C over 0.5 h. The reaction mixture was stirred at 25 °C for 15.5 h, then filtered and the filtrate was washed with water and brine. The organic layer was dried and concentrated to give tert-butyl N-methyl-N-[2-[methyl(propyl)carbamoyl]oxyethyl]carbamate (380 mg; Compound BG-2) as a colorless oil.

Step 3. Preparation of 2-(methylamino)ethyl-N-methyl-N-propyl-carbamate hydrochloride (compound BG-3)

tert-Butyl N-methyl N-[2-[methyl(propyl)carbamoyl]oxyethyl]carbamate (380 mg; Compound BG-2) was added to a solution of HCl in EA (13.7 mL; 1 M). The mixture was stirred at 0°C for 0.5 h. The mixture was then stirred at 25°C for another 15.5 h and concentrated to give 2-(methylamino)ethyl N-methyl-N-propyl carbamate hydrochloride (300 mg; Compound BG-3) as a colorless oil.

Step 4. Preparation of 2-[chlorocarbonyl(methyl)amino]ethyl N-methyl-N-propyl carbamate (intermediate BG)

Intermediate BG was prepared in analogy to intermediate AP, using 2-(methylamino)ethyl N-methyl-N-propyl carbamate hydrochloride (330 mg; compound BG-3) instead of ethyl 2-(methylamino)acetate hydrochloride. 2-[chlorocarbonyl(methyl)amino]ethyl N-methyl-N-propyl carbamate (300 mg; intermediate BG) was obtained and used in the next step without further purification.

Intermediate connection HV

2-[Chlorocarbonyl(methyl)amino]ethyl-N,N-diethylcarbamate

Step 1. Obtaining tert-butyl N-(2-hydroxyethyl)-N-methyl carbamate (compound BH-1)

To a solution of 2-(methylamino)ethanol (10 g, 133.14 mmol) in DCM (10 ml) was added Boc ₂ O (34.87 g, 159.77 mmol) at 25 °C. The mixture was stirred at 25 °C for 16 h and then concentrated, the residue was purified by column chromatography to give tert-butyl N-(2-hydroxyethyl)-N-methyl carbamate (20 g; compound BH-1) as a colorless oil.

Stage 2. Obtaining 2-[tert-butoxycarbonyl(methyl)amino]ethyl-N,N-diethylcarbamate (compound BH-2)

To a solution of tert-butyl N-(2-hydroxyethyl)-N-methyl carbamate (200 mg, 1.14 mmol; compound BH-1) and _Et3N (578 mg, 5.71 mmol) in DCM (5 mL) was added dropwise at 0 °C over 0.5 h N,N-diethylcarbamoyl chloride (248 mg, 1.83 mmol) and stirred at 25 °C for 15.5 h. After filtration, the filtrate was washed with water and brine. The organic layer was dried and concentrated to give 2-[tert-butoxycarbonyl(methyl)amino]ethyl N,N-diethylcarbamate (313 mg; compound BH-2) as a colorless oil.

Stage 3. Obtaining 2-(methylamino)ethyl-N,N-diethylcarbamate hydrochloride (compound BH-3)

2-[tert-Butoxycarbonyl(methyl)amino]ethyl N,N-diethylcarbamate (436 mg; 1.77 mmol; compound BH-2) was added to a solution of HCl in EA (17 ml; 1 M). The mixture was stirred at 0 °C for 0.5 h. Then the mixture was stirred at 25 °C for another 15.5 h and concentrated to give 2-(methylamino)ethyl N,N-diethylcarbamate hydrochloride (230 mg; compound BH-3) as a colorless oil.

Step 4. Preparation of 2-[chlorocarbonyl(methyl)amino]ethyl-N,N-diethylcarbamate (intermediate compound BH)

Intermediate BH was prepared in analogy to intermediate AP, using 2-(methylamino)ethyl N,N-diethylcarbamate hydrochloride (274 mg; compound BH-3) instead of ethyl 2-(methylamino)acetate hydrochloride. Crude 2-[chlorocarbonyl(methyl)amino]ethyl N,N-diethylcarbamate (250 mg; intermediate BH) was obtained and used in the next step without further purification.

BI Intermediate Connection

2-[Chlorocarbonyl(methyl)amino]ethyl ethyl carbonate

Step 1. Preparation of tert-butyl N-(2-hydroxyethyl)-N-methyl carbamate (compound BI-1)

To a solution of 2-(methylamino)ethanol (1 g, 13.31 mmol) in DCM (10 mL) was added Boc ₂ O (3.49 g, 15.98 mmol) at 25 °C. The reaction mixture was stirred at 25 °C for 16 h, then concentrated to give the crude product, which was purified by column chromatography to give tert-butyl N-(2-hydroxyethyl)-N-methyl carbamate (1.6 g; compound BI-1) as a colorless oil.

Step 2. Preparation of 2-[tert-butoxycarbonyl(methyl)amino]ethyl methyl carbonate (compound BI-2)

To a solution of tert-butyl N-(2-hydroxyethyl)-N-methyl carbamate (1 g; Compound BI-1), DMAP (0.1 g), and pyridine (1.15 g; 11.41 mmol) in EA (20 mL) was added dropwise at -10 °C. The mixture was stirred at -10 °C for 1 h. The reaction mixture was filtered, and the filtrate was washed with 5% citric acid solution and brine. The organic layer was dried and concentrated to give 2-[tert-butoxycarbonyl(methyl)amino]ethyl methyl carbonate (1.22 g; Compound BI-2) as a colorless oil.

Step 3. Obtaining ethyl 2-(methylamino)ethyl carbonate hydrochloride (compound BI-3)

2-[tert-Butoxycarbonyl(methyl)amino]ethyl methyl carbonate (1.22 g; 4.94 mmol; compound BI-2) was added to a solution of HCl in EA (10 mL; 40 mmol) and the mixture was stirred at 0°C for 0.5 h and at 25°C for another 15.5 h. The reaction mixture was concentrated to give ethyl 2-(methylamino)ethyl carbonate hydrochloride (1.06 g; compound BI-3).

Step 4. Preparation of 2-[chlorocarbonyl(methyl)amino]ethyl ethyl carbonate (intermediate BI)

Intermediate BI was prepared in analogy to intermediate AP, using ethyl 2-(methylamino)ethyl carbonate hydrochloride (150 mg; intermediate BI-3) instead of ethyl 2-(methylamino)acetate hydrochloride. Crude 2-[chlorocarbonyl(methyl)amino]ethyl ethyl carbonate (145 mg; intermediate BI) was obtained and used in the next step without further purification.

PREPARATORY EXAMPLES

Example 1

6-Amino-9-benzyl-N-methyl-8-oxo-N-propyl-2-(propylsulfonimidoyl)purine-7-carboxamide

Method A

Step 1. Preparation of 4-amino-3-benzyl-2-oxo-1H-imidazole-5-carbonitrile (compound 1a)

To a solution of aminomalononitrile p-toluenesulfonate (25 g, 98.5 mmol; TCI, Cat. No.: A1119-25G) in anhydrous THF (100 mL) were added benzyl isocyanate (13.2 g, 98.5 mmol) and TEA (10.2 g, 79.0 mmol) at RT. After stirring at RT for 24 h, the reaction mixture was concentrated in vacuo and the residue was partitioned between EtOAc (500 mL) and water (250 mL). The separated organic layer was washed twice with brine (50 mL) and extracted twice with sodium hydroxide solution (50 mL, 1 N). The combined sodium hydroxide solution was neutralized with 10 wt % sodium hydrogen sulfate solution and extracted with EtOAc. The separated organic layer was washed with brine, dried _{over Na2SO4} , filtered and concentrated in vacuo. The residue was triturated with 2-isopropoxypropane and the suspension was then filtered to give 4-amino-3-benzyl-2-oxo-1H-imidazole-5-carbonitrile (15 g; compound 1a) as a yellow solid. The product was used in the next step without further purification. MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 215.

Step 2. Preparation of 6-amino-9-benzyl-2-sulfanyl-7H-purin-8-one (compound 1b)

To a solution of 4-amino-3-benzyl-2-oxo-1H-imidazole-5-carbonitrile (15.0 g, 70.0 mmol; compound 1a) in THF (700 mL) was added dropwise benzoyl isothiocyanate (28.6 g, 175.1 mmol; TCI, catalog number: A11596-100G). After stirring at RT for 12 h, the reaction mixture was concentrated in vacuo. The residue was triturated with diethyl ether (100 mL) and the resulting precipitate was collected by filtration.

To a solution of the obtained residue in THF (700 mL) was added sodium hydroxide solution (70 mL; 2 N). The mixture was refluxed for 50 h and then acidified to pH 3 using 10 wt % aqueous sodium hydrogen sulfate solution. The resulting precipitate was collected by filtration to give crude 6-amino-9-benzyl-2-sulfanyl-7H-purin-8-one (8.1 g; compound 1b) as a yellow solid. The product was used in the next step without further purification. MS: found (ESI ⁺ ) [(M + H) ⁺ ]: 274.

Step 3. Preparation of 6-amino-9-benzyl-2-(2-propylsulfanyl)-7H-purin-8-one (compound 1c)

To a solution of 6-amino-9-benzyl-2-sulfanyl-7H-purin-8-one (5.46 g, 20.0 mmol; compound 1b) in DMF was added potassium carbonate (2.76 g, 20.0 mmol). Then 1-bromopropane (2.44 g, 20.0 mmol; TCI, catalog number: B0638-500G) in DMF (5.0 mL) was slowly added to the previous solution. After stirring at RT for 12 h, the reaction mixture was poured into water (200 mL), then acidified using 10 wt % aqueous sodium hydrogen sulfate solution and extracted twice with EtOAc (100 mL). The organic layer was washed with brine, dried _{over Na2SO4} and concentrated in vacuo to give the crude product, which was purified by flash chromatography on silica gel to give 6-amino-9-benzyl-2-(2-propylsulfanyl)-7H-purin-8-one (4.8 g; compound 1c) as a white solid. MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 316.

Step 4. Preparation of 6-amino-9-benzyl-2-propylsulfinyl-7H-purin-8-one (compound 1d)

To a suspension of 6-amino-9-benzyl-2-(2-propylsulfanyl)-7H-purin-8-one (2.7 g, 8.7 mmol; compound 1c) in DCM/MeOH (500 mL, v/v=1:1) was added 3-chloroperbenzoic acid (2.15 g, 8.7 mmol; 70% purity, Aldrich, catalog number: 273031-100G). After stirring the reaction mixture for 2 h, the volume of the reaction mixture was reduced in vacuo to approximately 50 mL. The resulting precipitate was collected by filtration, washed with methanol and dried to give 6-amino-9-benzyl-2-propylsulfinyl-7H-purin-8-one (1.0 g; compound 1d) as a white solid. The product was used in the next step without further purification. MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 332.

Step 5. Preparation of 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e)

To a solution of 6-amino-9-benzyl-2-propylsulfinyl-7H-purin-8-one (1.52 g, 4.6 mmol; compound 1d) in Eaton's reagent (40 mL; phosphorus pentoxide; 7.5 wt % in methanesulfonic acid; Aldrich, catalog no.: 380814-100ML) was added sodium azide (360 mg, 5.5 mmol) at 50 °C. After stirring at this temperature for 30 min, the reaction mixture was cooled to RT and poured into saturated aqueous sodium bicarbonate solution. The reaction mixture was extracted twice with n-BuOH (100 mL) and the organic phase was concentrated in vacuo. The residue was purified by preparative HPLC to afford 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (1.2 g; compound 1e) as a white solid. ¹ H NMR (400 MHz, dimethyl sulfoxide (DMSO)-d ₆ ) δ ^ppm : 10.65 (br. s., 1H), 7.26-7.37 (m, 5H), 6.98 (br. s., 2H), 4.97 (s, 2H), 4.02 (s, 1H), 3.33 (t, J=7.53 Hz, 2H), 1.55-1.74 (m, 2H), 0.92 (t, J=7.53 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 347.

After separation of compound 1e by chiral HPLC, compound 1e-A (slower eluting; 500 mg) and compound 1e-B (faster eluting; 490 mg) were obtained as a white solid (separation conditions: 5%→40% methanol with (0.05% diethylamine (DEA))/CO ₂ on a ChiralPak AS-3 column).

Compound 1e-A: ^1H -NMR (DMSO- _d6 , 400 MHz) δ ^ppm : 10.56 (s, 1H), 7.21-7.46 (m, 5H), 7.03 (s, 2H), 4.96 (s, 2H), 4.04 (s, 1H), 3.25-3.33 (m, 2H), 1.59-1.67 (m, 2H), 0.92 (t, J=7.4 Hz, 3H).

Compound 1e-B: ^1H -NMR (DMSO- _d6 , 400 MHz) δ ^ppm : 10.57 (s, 1H), 7.23-7.39 (m, 5H), 6.97 (s, 2H), 4.96 (s, 2H), 4.05 (s, 1H), 3.31-3.30 (m, 2H), 1.49-1.74 (m, 2H), 0.91 (t, J=7.4 Hz, 3H).

Step 6. Preparation of 6-amino-9-benzyl-N-methyl-8-oxo-N-propyl-2-(propylsulfonimidoyl)purine-7-carboxamide (compound from Example 1)

To a solution of 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (300 mg; compound 1e), pyridine (329 mg; 4.2 mmol) and DIPEA (538 mg; 4.2 mmol) in NMP (5 ml) was added N-methyl-N-propylcarbamoyl chloride (564 mg; 4.2 mmol; intermediate AA) at RT. The mixture was stirred at RT for 10 h. The reaction mixture was concentrated and the residue was purified by preparative HPLC, yielding 6-amino-9-benzyl-N-methyl-8-oxo-N-propyl-2-(propylsulfonimidoyl)purine-7-carboxamide (108 mg; compound from example 1) as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.45-7.24 (m, 5H), 6.89 (s, 2H), 5.01 (s, 2H), 4.17 (s, 1H), 3.44-3.34 (m, 2H), 3.36-3.34 (m, 2H), 3.10-3.00 (m, 3H), 1.74-1.52 (m, 4H), 1.01-0.72 (m, 6H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 446.

After separation of the compound from Example 1 by chiral HPLC, the compound from Example 1-A (slower eluting; 50 mg) and the compound from Example 1-B (faster eluting; 40 mg) were obtained as a white solid using 5%→40% isopropanol with (0.05% DEA)/CO ₂ on a ChiralPak AD-3 column.

Compound from Example 1-A: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.44-7.24 (m, 5H), 6.89 (s, 2H), 5.01 (s, 2H), 4.17 (s, 1H), 3.44-3.37 (m, 2H), 3.37-3.35 (m, 2H), 3.10-3.00 (m, 3H), 1.74-1.52 (m, 4H), 1.00-0.72 (m, 6H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 446.

Compound from Example 1-B: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.45-7.26 (m, 5H), 6.88 (s, 2H), 5.01 (s, 2H), 4.15 (s, 1H), 3.44-3.36 (m, 2H), 3.34 (s, 2H), 3.10-3.01 (m, 3H), 1.77-1.52 (m, 4H), 1.02-0.67 (m, 6H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 446.

Method B. Alternative method for preparing 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e)

Step 1. Preparation of N-benzyl-6-chloro-5-nitro-2-propylsulfanyl-pyrimidin-4-amine (compound 1f)

To a solution of 4,6-dichloro-5-nitro-2-propylsulfanylpyrimidine (150.0 g, 559.5 mmol) and DIPEA (108.5 g, 839.2 mmol) in THF (1.5 L) was added phenylmethanamine (60.0 g, 559.5 mmol) in THF (200 mL) slowly at -78 °C. After complete addition, the mixture was warmed to 25 °C and stirred at this temperature for 16 h. The resulting mixture was diluted with EA (1 L), washed three times with water (400 mL) and brine (500 mL). The separated organic phase was dried over _Na2SO4 , filtered and concentrated in vacuo to give N-benzyl-6-chloro-5-nitro-2-propylsulfanyl-pyrimidin-4-amine (180.0 g; compound 1f) as _a yellow solid, which was used in the next step without further purification. MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 339.1.

Step 2. Preparation of N4-benzyl-6-chloro-2-propylsulfanyl-pyrimidine-4,5-diamine (compound 1g)

To a solution of N-benzyl-6-chloro-5-nitro-2-propylsulfanylpyrimidin-4-amine (180 g; compound 1f) and HOAc (319 g; 5.31 mol) in THF (3.0 L) was added Zn (174 g; 2.66 mol) slowly at 25 °C. After complete addition, the mixture was stirred at 25 °C for 16 h. The reaction mixture was filtered and the filtrate was basified with saturated aqueous NaHCO ₃ solution (800 mL), extracted three times with EA (400 mL), dried over Na ₂ SO ₄ and concentrated in vacuo. The residue was purified by silica gel chromatography to give N4-benzyl-6-chloro-2-propylsulfanylpyrimidine-4,5-diamine (125 g; compound 1g) as a brown solid. MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 309.1.

Step 3. Preparation of 9-benzyl-6-chloro-2-propylsulfanyl-7H-purin-8-one (compound 1h)

A solution of N-benzyl-6-chloro-2-(propylsulfanyl)pyrimidine-4,5-diamine (72.0 g, 233.1 mmol; compound 1g) and CDI (75.2 g, 233.1 mmol) in THF (800 mL) was stirred at 80 °C for 16 h. The resulting mixture was diluted with EA (400 mL), washed twice with water (200 mL) and brine (200 mL). The separated organic layer was dried over Na ₂ SO ₄ , concentrated in vacuo. The residue was washed with MTBE (200 mL) to give 9-benzyl-6-chloro-2-propylsulfanyl-7H-purin-8-one (58.0 g; compound 1h) as a white solid, which was used in the next step without further purification. MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 335.1.

Step 4. Preparation of 9-benzyl-6-[(4-methoxyphenyl)methylamino]-2-propylsulfanyl-7H-purin-8-one (compound 1i)

A solution of 9-benzyl-6-chloro-2-propylsulfanyl-7H-purin-8-one (58.0 g; compound 1h) and _PMBNH2 (54.7 g; 398.42 mmol) in n-BuOH (600 mL) was stirred at 120 °C for 20 h. The reaction mixture was concentrated and the residue was washed with MTBE (400 mL) to give 9-benzyl-6-[(4-methoxyphenyl)methylamino]-2-propylsulfanyl-7H-purin-8-one (75 g; compound 1i) as a white solid, which was used in the next step without further purification. MS: found (ESI ⁺ ) [(M + H) ⁺ ]: 436.2.

Step 5. Preparation of 6-amino-9-benzyl-2-propylsulfanyl-7H-purin-8-one (compound 1c)

9-Benzyl-6-[(4-methoxyphenyl)methylamino]-2-propylsulfanyl-7H-purin-8-one (87.0 g; compound 1i) in TFA (200 mL) was stirred at 80 °C for 16 h. The resulting reaction mixture was concentrated, basified with saturated aqueous NaHCO ₃ solution (600 mL). The resulting precipitate was collected by filtration and washed (PE/DCM=2:1, 400 mL) to give 6-amino-9-benzyl-2-propylsulfanyl-7H-purin-8-one (38.0 g; compound 1c) as a white solid. MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 316.1.

Step 6. Preparation of 6-amino-9-benzyl-2-propylsulfinyl-7H-purin-8-one (compound 1d)

A solution of m-CPBA (22.98 g, 113.2 mmol) in THF (50 mL) was added dropwise to a suspension of 6-amino-9-benzyl-2-propylsulfanyl-7H-purin-8-one (35.0 g; compound 1c) in THF (200 mL) at 0 °C. After complete addition, the reaction mixture was stirred at 25 °C for 0.5 h. The mixture was filtered and washed with MeCN (400 mL), MTBE (500 mL) to give 6-amino-9-benzyl-2-propylsulfinyl-7H-purin-8-one (35.1 g; compound 1d) as a white solid, which was used in the next step without further purification. MS: found (ESI ⁺ ) [(M + H) ⁺ ]: 332.1.

Step 7. Preparation of 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e)

To a solution of 6-amino-9-benzyl-2-propylsulfinyl-7H-purin-8-one (34.0 g; compound 1d) in Eaton's reagent (170.0 mL; 7.5 wt % phosphorus pentoxide in methanesulfonic acid) was slowly added NaN ₃ (15.34 g; 253.97 mmol) at 60 °C. The mixture was then stirred at 60 °C for 30 min. The resulting reaction mixture was cooled to 25 °C, poured into ice-cold NH ₃ H ₂ O (500 mL; 1 mol/L), extracted four times with n-BuOH (100 mL), and concentrated in vacuo. The residue was purified by preparative HPLC to afford 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (10 g; compound 1e). ¹ H NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 10.65 (br s, 1H), 7.26-7.37 (m, 5H), 6.98 (br s, 2H), 4.97 (s, 2H), 4.02 (s, 1H), 3.33 (t, J=7.53 Hz, 2H), 1.55-1.74 (m, 2H), 0.92 (t, J=7.53 Hz, 3H). MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 347.

Example 2

6-Amino-9-benzyl-N-(2-methoxyethyl)-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide

The title compound was prepared in analogy to step 6 of method A from Example 1, substituting N-(2-methoxyethyl)-N-methylcarbamoyl chloride (intermediate AB) for N-methyl-N-propylcarbamoyl chloride (intermediate AA). 6-Amino-9-benzyl-N-(2-methoxyethyl)-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide (120 mg; the compound from Example 2) was obtained as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.27-7.39 (m, 5H), 6.89 (br. s., 1H), 6.78 (br. s., 1H), 5.00 (s, 2H), 4.16 (br. d, J=4 Hz, 1H), 3.62 (br. dd, J=4; 12 Hz, 2H), 3.28-3.42 (m, 6H), 3.12 (d, J=12 Hz, 3H), 3.05 (s, 1H), 1.58-1.72 (m, 2H), 0.93 (t, J=8 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 462.

After separation of the compound from Example 2 by chiral HPLC, the compound from Example 2-A (faster eluting; 33 mg) and the compound from Example 2-B (slower eluting; 46 mg) were obtained as a white solid using 5%→40% methanol with (0.05% DEA)/CO ₂ on a ChiralPak OJ-3 column.

Compound from example 2-A: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.27-7.39 (m, 5H), 6.89 (br. s., 1H), 6.78 (br. s., 1H), 5.00 (s, 2H), 4.16 (br. d, J=4 Hz, 1H), 3.62 (br. dd, J=4; 12 Hz, 2H), 3.28-3.42 (m, 6H), 3.12 (d, J=12 Hz, 3H), 3.05 (s, 1H), 1.58-1.72 (m, 2H), 0.93 (t, J=8 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 462.

Compound from example 2-B: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.27-7.39 (m, 5H), 6.89 (br. s., 1H), 6.78 (br. s., 1H), 5.00 (s, 2H), 4.16 (br. d, J=4 Hz, 1H), 3.62 (br. dd, J=4; 12 Hz, 2H), 3.28-3.42 (m, 6H), 3.12 (d, J=12 Hz, 3H), 3.05 (s, 1H), 1.58-1.72 (m, 2H), 0.93 (t, J=8 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 462.

Example 3

6-Amino-9-benzyl-N-ethyl-8-oxo-N-propyl-2-(propylsulfonimidoyl)purine-7-carboxamide

The title compound was prepared in analogy to step 6 of method A from Example 1, using N-ethyl-N-propyl carbamoyl chloride (intermediate AC) instead of N-methyl-N-propyl carbamoyl chloride (intermediate AA). 6-Amino-9-benzyl-N-ethyl-8-oxo-N-propyl-2-(propylsulfonimidoyl)purine-7-carboxamide (51 mg; the compound from Example 3) was obtained as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.27-7.39 (m, 5H), 6.85 (br. s., 2H), 4.99 (s, 2H), 4.20 (br. d, J=8.0 Hz, 1H), 3.13-3.54 (m, 4H), 1.46-1.72 (m, 4H), 1.30-1.39 (m, 1H), 1.00-1.26 (m, 6H), 0.81-0.95 (m, 5H), 0.73 (t, J=8 Hz, 1H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 474.

Example 4

6-Amino-9-benzyl-7-[4-(1-piperidyl)piperidine-1-carbonyl]-2-(propylsulfonimidoyl)purin-8-one

The title compound was prepared in analogy to step 6 of method A of Example 1, using (1,4'-bipiperidine)-1'-carbonyl chloride instead of N-methyl-N-propylcarbamoyl chloride (intermediate AA). 6-Amino-9-benzyl-7-[4-(1-piperidyl)piperidine-1-carbonyl]-2-(propylsulfonimidoyl)purin-8-one (55 mg; the compound from Example 4) was obtained as a white powder. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.39-7.27 (m, 5H), 6.97 (br. s., 2H), 4.99 (s, 2H), 4.20 (br. s., 2H), 3.85 (d, J=12.5 Hz, 1H), 3.43-3.15 (m, 3H), 2.96 (t, J=12.3 Hz, 2H), 2.56 (m, 4H), 1.83 (m, 1H), 1.79-1.54 (m, 4H), 1.50 (br. s., 4H), 1.45-1.33 (m, 3H), 0.93 (t, J=7.4 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 541.2.

Example 5

6-Amino-9-benzyl-N-ethyl-N-(2-methoxyethyl)-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide

The title compound was prepared in analogy to step 6 of method A from Example 1, using N-ethyl-N-(2-methoxyethyl)carbamoyl chloride (intermediate AD) instead of N-methyl-N-propylcarbamoyl chloride (intermediate AA). 6-Amino-9-benzyl-N-ethyl-N-(2-methoxyethyl)-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide (34 mg; the compound from Example 5) was obtained as a white powder. ¹ H NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.39-7.28 (m, 5H), 6.89 (br. s., 1H), 6.74 (br. s., 1H), 4.99 (s, 2H), 4.17 (d, J=8.1 Hz, 1H), 3.67 (br. s., 2H), 3.63-3.51 (m, 2H), 3.50-3.34 (m, 4H), 3.29 (s, 1H), 3.11 (s, 2H), 1.73-1.59 (m, 2H), 1.23-1.07 (m, 3H), 0.93 (t, J=7.5 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 476.3.

Example 6

6-Amino-9-benzyl-N-butyl-N-ethyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide

The title compound was prepared in analogy to step 6 of method A from Example 1, using N-butyl-N-ethylcarbamoyl chloride (intermediate AE) instead of N-methyl-N-propylcarbamoyl chloride (intermediate AA). 6-Amino-9-benzyl-N-butyl-N-ethyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide (51 mg; the compound from Example 6) was obtained as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.27-7.39 (m, 5H), 6.85 (br. s., 2H), 4.99 (s, 2H), 4.20 (br. d, J=8.0 Hz, 1H), 3.13-3.54 (m, 4H), 1.46-1.72 (m, 4H), 1.30-1.39 (m, 1H), 1.00-1.26 (m, 6H), 0.81-0.95 (m, 5H), 0.73 (t, J=8 Hz, 1H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 474.

Example 7

6-Amino-9-benzyl-N-(2-methoxyethyl)-8-oxo-N-propyl-2-(propylsulfonimidoyl)purine-7-carboxamide

The title compound was prepared in analogy to step 6 of method A from Example 1, using N-ethyl-N-(2-methoxyethyl)carbamoyl chloride (intermediate AF) instead of N-methyl-N-propylcarbamoyl chloride (intermediate AA). 6-Amino-9-benzyl-N-(2-methoxyethyl)-8-oxo-N-propyl-2-(propylsulfonimidoyl)purine-7-carboxamide (35 mg; the compound from Example 7) was obtained as a white powder. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.40-7.28 (m, 5H), 6.89 (br. s., 1H), 6.75 (br. s., 1H), 5.00 (d, J=5.5 Hz, 2H), 4.24-4.16 (m, 1H), 3.77 (br. s., 1H), 3.67 (br. s., 1H), 3.62-3.53 (m, 1H), 3.42-3.27 (m, 5H), 3.23-3.02 (m, 3H), 1.66-1.38 (m, 4H), 0.96-0.70 (m, 6H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 490.5.

Example 8

6-Amino-9-benzyl-N,N-bis(2-methoxyethyl)-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide

The title compound was prepared in analogy to step 6 of method A from Example 1, using bis(2-methoxyethyl)carbamoyl chloride (intermediate AG) instead of N-methyl-N-propylcarbamoyl chloride (intermediate AA). 6-Amino-9-benzyl-N,N-bis(2-methoxyethyl)-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide (35 mg; the compound from Example 8) was obtained as a white powder. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.40-7.28 (m, 5H), 6.83 (br. s., 2H), 4.99 (s, 2H), 3.71 (br. s., 3H), 3.52-3.27 (m, 11H), 3.09 (s, 3H), 1.73-1.59 (m, 2H), 0.93 (t, J=7.5 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 506.

Example 9

6-Amino-7-(azetidine-1-carbonyl)-9-benzyl-2-(propylsulfonimidoyl)purin-8-one

The title compound was prepared in analogy to step 6 of method A of Example 1, using azetidine-1-carbonyl chloride (intermediate AH) instead of N-methyl-N-propylcarbamoyl chloride (intermediate AA). 6-Amino-7-(azetidine-1-carbonyl)-9-benzyl-2-(propylsulfonimidoyl)purin-8-one (120 mg; the compound from Example 9) was obtained as a white powder. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.02-7.43 (m, 7H), 4.99 (s, 2H), 4.31 (t, J=7.65 Hz, 2H), 4.08-4.23 (m, 3H), 3.34-3.41 (m, 2H), 2.28 (m, 2H), 1.56-1.73 (m, 2H), 0.93 (t, J=7.40 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 430.

Example 10

6-Amino-9-benzyl-N-isopropyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide

The title compound was prepared in analogy to step 6 of method A from Example 1, using N-isopropyl-N-methylcarbamoyl chloride (intermediate AI) instead of N-methyl-N-propylcarbamoyl chloride (intermediate AA). 6-Amino-9-benzyl-N-isopropyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide (97 mg; the compound from Example 10) was obtained as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.27-7.39 (m, 5H), 6.87 (br. s., 2H), 4.99 (s, 2H), 4.38-4.45 (m, 1H), 4.09-4.21 (m, 1H), 3.29-3.43 (m, 2H), 2.89-2.95 (m, 3H), 1.58-1.73 (m, 2H), 1.21 (br d, J=8 Hz, 6H), 0.93 (t, J=8 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 446.

Example 11

6-Amino-9-benzyl-7-(4-methylpiperazine-1-carbonyl)-2-(propylsulfonimidoyl)purin-8-one

The title compound was prepared in analogy to step 6 of method A of Example 1, using 4-methylpiperazine-1-carbonyl chloride instead of N-methyl-N-propylcarbamoyl chloride (intermediate AA). 6-Amino-9-benzyl-7-(4-methylpiperazine-1-carbonyl)-2-(propylsulfonimidoyl)purin-8-one (59.5 mg; the compound from Example 11) was obtained as a yellow solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.39-7.31 (m, 5H), 6.99 (s, 2H), 4.98 (s, 2H), 4.18 (s, 1H), 3.58-3.49 (m, 6H), 2.42 (m, 4H), 2.22 (s, 3H), 1.66-1.61 (m, 2H), 0.95-0.91 (t, J=7.2 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 473.

Example 12

6-Amino-9-benzyl-N-(3-methoxypropyl)-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide

The title compound was prepared in analogy to step 6 of method A of Example 1, using N-(3-methoxypropyl)-N-methylcarbamoyl chloride instead of N-methyl-N-propylcarbamoyl chloride (intermediate AA). 6-Amino-9-benzyl-N-(3-methoxypropyl)-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide (92.2 mg; the compound from Example 12) was obtained as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.23-7.45 (m, 5H), 6.94 (s., 2H), 4.93-5.08 (m, 2H), 4.19 (s, 1H), 3.30-3.62 (m, 6H), 3.25 (s, 3H), 3.02-3.10 (m, 3H), 1.74-1.90 (m, 2H), 1.55-1.77 (m, 2H), 0.98-0.82 (m, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 476.3.

Example 13

6-Amino-9-benzyl-N-isobutyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide

The title compound was prepared in analogy to step 6 of method A from Example 1, using N-isobutyl-N-methylcarbamoyl chloride (intermediate AL) instead of N-methyl-N-propylcarbamoyl chloride (intermediate AA). 6-Amino-9-benzyl-N-isobutyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide (64 mg; the compound from Example 13) was obtained as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.27-7.40 (m, 5H), 6.89 (br. s., 2H), 5.00 (s, 2H), 4.16 (br. s., 1H), 3.25-3.44 (m, 4H), 3.07 (s, 2H), 3.03 (s, 1H), 1.87-2.09 (m, 1H), 1.57-1.74 (m, 2H), 0.75-0.99 (m, 9H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 460.

Example 14

Ethyl 2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methyl-amino]acetate

The title compound was prepared in analogy to step 6 of method A of Example 1, using ethyl 2-((chlorocarbonyl)(methyl)amino)acetate (intermediate AP) instead of N-methyl-N-propylcarbamoyl chloride (intermediate AA). Ethyl 2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methylamino]acetate (38 mg; the compound from Example 14) was obtained as a light yellow powder. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.41-7.27 (m, 5H), 6.82 (br. s., 1H), 5.04-4.95 (m, 2H), 4.35 (br. s., 1H), 4.28 (br. s., 1H), 4.23-4.16 (m, 2H), 4.08 (q, J=7.2 Hz, 1H), 3.43-3.28 (m, 3H), 3.15 (s, 2H), 3.08 (s, 1H), 1.71-1.58 (m, 2H), 1.24 (t, J=7.0 Hz, 2H), 1.12 (t, J=7.0 Hz, 1H), 0.93 (t, J=7.4 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 490.

Example 15

Ethyl 3-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]propanoate

The title compound was prepared in analogy to step 6 of method A of Example 1, using ethyl 3-((chlorocarbonyl)(methyl)amino)propanoate instead of N-methyl-N-propylcarbamoyl chloride (intermediate AA).

Ethyl 3-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methylamino]propanoate (35 mg; the compound from Example 15) was obtained as a white powder. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.43-7.26 (m, 5H), 6.93 (br. s., 2H), 4.99 (s, 2H), 4.16 (s, 1H), 4.08 (q, J=7.1 Hz, 1H), 3.99 (d, J=7.0 Hz, 1H), 3.67 (br. s., 2H), 3.40-3.29 (m, 2H), 3.08 (s, 2H), 2.99 (s, 1H), 2.71 (t, J=6.4 Hz, 2H), 1.74-1.56 (m, 2H), 1.27-1.05 (m, 3Н), 0.93 (t, J=7.5 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 504.

Example 16

tert-Butyl-3-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]propanoate

The title compound was prepared in analogy to step 6 of method A from Example 1, using tert-butyl 3-[chlorocarbonyl(methyl)amino]propanoate (intermediate AR) instead of N-methyl-N-propylcarbamoyl chloride (intermediate AA). tert-Butyl 3-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methylamino]propanoate (60 mg; the compound from Example 16) was obtained as a white powder. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.41-7.27 (m, 5H), 6.93 (br. s., 2H), 4.99 (s, 2H), 4.15 (s, 1H), 3.64 (br. s., 2H), 3.51-3.33 (m, 2H), 3.08 (s, 2H), 2.98 (s, 1H), 2.62 (t, J=6.9 Hz, 2H), 1.71-1.57 (m, 2H), 1.41 (s, 6H), 1.34 (s, 3H), 0.93 (t, J=7.4 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 532.

Example 17

Ethyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methyl-amino]propanoate

The title compound was prepared in analogy to step 6 of method A from Example 1, using ethyl (2S)-2-[chlorocarbonyl(methyl)amino]propanoate (intermediate AS) instead of N-methyl-N-propylcarbamoyl chloride (intermediate AA). Ethyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methylamino]propanoate (34.1 mg; the compound from Example 17) was obtained as a yellow solid. ¹ H-NMR (300 MHz, DMSO-d ₆ ) δ ^ppm : 7.22-7.49 (m, 5H), 6.78 (br. s., 2H), 4.93-5.08 (m, 2H), 4.75 (br. s., 1H), 3.96-4.29 (m, 3H), 3.30-3.46 (m, 2H), 3.09 (s, 2H), 2.93 (br. s., 1H), 1.55-1.77 (m, 2H), 1.48 (d, J=7.16 Hz, 3H), 1.09-1.29 (m, 3H), 0.94 (t, J=7.44 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H ⁾⁺ ]: 504.2.

Example 18

tert-Butyl-(2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]-4-methylpentanoate

The title compound was prepared in analogy to step 6 of method A from Example 1, substituting tert-butyl (2S)-2-[chlorocarbonyl(methyl)amino]-4-methylpentanoate (intermediate AT) for N-methyl-N-propylcarbamoyl chloride (intermediate AA). tert-Butyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methylamino]-4-methylpentanoate (22 mg; the compound from Example 18) was obtained as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.42-7.27 (m, 5H), 6.78 (br. s., 2H), 5.05-4.96 (m, 2H), 4.78 (br. s., 1H), 4.33 (br. s., 1H), 3.51-3.37 (m, 2H), 3.01 (s, 3H), 1.75-1.54 (m, 4H), 1.44 (s, 8H), 1.33-1.11 (m, 2H), 0.99-0.82 (m, 9H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 574.3.

Example 19

Isopropyl-(2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]-4-methylpentanoate

The title compound was prepared in analogy to step 6 of method A from Example 1, substituting isopropyl (2S)-2-[chlorocarbonyl(methyl)amino]-4-methylpentanoate (intermediate AU) for N-methyl-N-propylcarbamoyl chloride (intermediate AA). Isopropyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methylamino]-4-methylpentanoate (43 mg; the compound from Example 19) was obtained as a white powder. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.43-7.27 (m, 5H), 6.75 (br. s., 2H), 5.05-4.94 (m, 3H), 4.88 (br. s., 1H), 4.19 (br. s., 1H), 3.43-3.34 (m, 2H), 3.01 (s, 3H), 1.91 (br. s., 1H), 1.77-1.56 (m, 4H), 1.25-1.16 (m, 6H), 0.99-0.83 (m, 9H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 560.3.

Example 20

Ethyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]-3-methylbutanoate

The title compound was prepared in analogy to step 6 of method A from Example 1, using ethyl (2S)-2-[chlorocarbonyl(methyl)amino]-3-methylbutanoate (intermediate AV) instead of N-methyl-N-propylcarbamoyl chloride (intermediate AA). Ethyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methylamino]-3-methylbutanoate (51.5 mg; the compound from Example 20) was obtained as a white powder. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.23-7.51 (m, 5H), 6.76 (br. s., 2H), 5.01 (br. s., 2H), 4.42 (br. s., 1H), 3.97-4.26 (m, 3H), 3.34-3.45 (m, 2H), 3.12 (br. s., 3H), 2.24 (br. s., 1H), 1.65 (br. s., 2H), 1.13-1.29 (m, 3H), 0.88-1.10 (m, 9H). MS: detected (ESI ⁺ ) [M+H) ⁺ ]: 532.2.

Example 21

Ethyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methyl-amino]-4-methylpentanoate

The title compound was prepared in analogy to step 6 of method A from Example 1, using ethyl (2S)-2-[chlorocarbonyl(methyl)amino]-4-methylpentanoate (intermediate AW) instead of N-methyl-N-propylcarbamoyl chloride (intermediate AA). Ethyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methylamino]-4-methylpentanoate (17.3 mg; the compound from Example 21) was obtained as a white powder. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.26-7.45 (m, 5H), 6.73 (br. s., 2H), 4.91-5.09 (m, 3H), 4.06-4.25 (m, 3H), 3.34-3.45 (m, 2H), 3.04 (br. s., 3H), 1.93 (br. s., 1H), 1.54-1.78 (m, 4H), 1.22 (t, J=7.09 Hz, 3H), 0.77-1.01 (m, 9H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 546.3.

Example 22

Ethyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]-3-phenylpropanoate

The title compound was prepared in analogy to step 6 of method A from Example 1, using ethyl (2S)-2-[chlorocarbonyl(methyl)amino]-3-phenylpropanoate (intermediate AX) instead of N-methyl-N-propylcarbamoyl chloride (intermediate AA). Ethyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methylamino]-3-phenylpropanoate (30 mg; the compound from Example 22) was obtained as a white powder. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.42-7.16 (m, 10H), 4.97 (s, 3H), 4.19 (q, J=7.1 Hz, 2H), 3.35-3.15 (m, 6H), 3.10-2.90 (m, 3H), 1.71-1.46 (m, 2H), 1.28-1.18 (m, 4H), 0.97-0.85 (m, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 580.

Example 23

Isopropyl-(2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)-purine-7-carbonyl]-methyl-amino]-3-phenylpropanoate

The title compound was prepared in analogy to step 6 of method A from Example 1, substituting isopropyl (2S)-2-[chlorocarbonyl(methyl)amino]-3-phenylpropanoate (intermediate AY) for N-methyl-N-propylcarbamoyl chloride (intermediate AA). Isopropyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methylamino]-3-phenylpropanoate (22 mg; the compound from Example 23) was obtained as a white powder. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.35-7.01 (m, 10H), 5.02-4.89 (m, 3H), 3.37-3.17 (m, 3H), 3.02-3.09 (m, 3H), 3.10-2.90 (m, 3H), 1.66-1.62 (m, 2H), 1.22-1.11 (m, 8H), 0.92 (t, J=7.4 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 594.

Example 24

tert-Butyl-(2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)-purine-7-carbonyl]-methyl-amino]-3-phenylpropanoate

The title compound was prepared in analogy to step 6 of method A from Example 1, substituting tert-butyl (2S)-2-[chlorocarbonyl(methyl)amino]-3-phenylpropanoate (intermediate AZ) for N-methyl-N-propylcarbamoyl chloride (intermediate AA). tert-Butyl (2S)-2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methylamino]-3-phenylpropanoate (34 mg; the compound from Example 24) was obtained as a white powder. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.42-7.16 (m, 10H), 5.03-4.90 (m, 3H), 3.68-3.24 (m, 5H), 3.24-3.09 (m, 2H), 3.01 (s, 3H), 1.68-1.57 (m, 2H), 1.43 (s, 9H), 0.99-0.85 (m, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 608.3.

Example 25

N-[2-[Acetyl(methyl)amino]ethyl]-6-amino-9-benzyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide

The title compound was prepared in analogy to step 6 of method A from Example 1, using N-[2-[acetyl(methyl)amino]ethyl]-N-methylcarbamoyl chloride (intermediate BA) instead of N-methyl-N-propylcarbamoyl chloride (intermediate AA). N-[2-[Acetyl(methyl)amino]ethyl]-6-amino-9-benzyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide (26.1 mg; the compound from Example 25) was obtained as a white powder. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.43-7.27 (m, 5H), 7.02 (br, 2H), 5.04-4.97 (m, 2H), 4.19-4.13 (m, 1H), 3.57 (d, J=5.5 Hz, 2H), 3.49-3.34 (m, 2H), 3.14 (s, 1H), 3.12-3.02 (m, 4H), 2.86 (d, J=7.5 Hz, 2H), 2.69-2.64 (m, 1H), 2.05 (s, 1H), 1.99 (s, 1H), 1.91-1.83 (m, 1H), 1.70-1.59 (m, 2H), 0.97-0.90 (m, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 503.2.

Example 26

Methyl N-[2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl]-N-methylcarbamate

The title compound was prepared in analogy to step 6 of method A from Example 1, substituting methyl N-[2-[chlorocarbonyl(methyl)amino]ethyl]-N-methylcarbamate (intermediate BB) for N-methyl-N-propylcarbamoyl chloride (intermediate AA). Methyl N-[2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methyl-amino]ethyl]-N-methylcarbamate (65 mg; the compound from Example 26) was obtained as a yellow solid. ¹ H-NMR (400 MHz, CDCl ₃ ) δ ^ppm : 7.29-7.49 (m, 5H), 5.63-5.92 (m, 2H), 5.03-5.17 (m, 2H), 3.43-3.69 (m, 8H), 3.13-3.27 (m, 3H), 2.96-3.05 (m, 2H), 2.72 (br. s., 1H), 1.05 (t, J=7.40 Hz, 3H), 1.87 (dd, J=14.12; 6.96 Hz, 2H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]:519.2.

Example 27

tert-Butyl N-[2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)-purine-7-carbonyl]-methyl-amino]ethyl]-N-methylcarbamate

The title compound was prepared in analogy to step 6 of method A from Example 1, substituting tert-butyl N-[2-[chlorocarbonyl(methyl)amino]ethyl]-N-methylcarbamate (intermediate BC) for N-methyl-N-propylcarbamoyl chloride (intermediate AA). tert-Butyl N-[2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl]-N-methylcarbamate (32 mg; the compound from Example 27) was obtained as a white powder. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.43-7.26 (m, 5H), 6.89 (br. s., 2H), 4.99 (d, J=5.0 Hz, 2H), 4.16 (s, 1H), 3.55 (br. s., 2H), 3.48-3.34 (m, 2H), 3.10 (s, 2H), 3.07 (s, 1H), 2.86 (d, J=12.8 Hz, 2H), 2.74 (d, J=9.5 Hz, 1H), 2.70-2.60 (m, 1H), 1.72-1.54 (m, 2H), 1.39 (s, 6H), 1.23 (s, 2H), 1.13 (s, 2H), 0.93 (t, J=7.4 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 562.

Example 28

Ethyl N-[2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl]-N-methylcarbamate

The title compound was prepared in analogy to step 6 of method A from Example 1, substituting ethyl N-[2-[chlorocarbonyl(methyl)amino]ethyl]-N-methylcarbamate (intermediate BD) for N-methyl-N-propylcarbamoyl chloride (intermediate AA). Ethyl N-[2-[[6-amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methyl-amino]ethyl]-N-methylcarbamate (87 mg; the compound from Example 28) was obtained as a yellow solid. ¹ H-NMR (400 MHz, CDCl ₃ ) δ ^ppm : 7.29-7.53 (m, 5H), 5.65-5.90 (m, 2H), 5.02-5.14 (m, 2H), 3.38-4.21 (m, 9H), 3.14-3.26 (m, 3H), 3.00 (br. s., 2H), 2.73 (s, 1H), 1.76-1.99 (m, 2H), 1.22-1.31 (m, 3H), 1.05 (s, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 533.2.

Example 29

2-[[6-Amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl-N-butyl-N-methylcarbamate

The title compound was prepared in analogy to step 6 of method A from Example 1, substituting 2-[chlorocarbonyl(methyl)amino]ethyl N-butyl N-methylcarbamate (intermediate BE) for N-methyl-N-propylcarbamoyl chloride (intermediate AA). 2-[[6-Amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methyl amino]ethyl N-butyl N-methylcarbamate (19 mg; the compound from Example 29) was obtained as a yellow solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.25-7.48 (m, 5H), 6.96 (br. s., 2H), 4.99 (s, 2H), 4.06-4.36 (m, 3H), 3.59-3.83 (m, 1H), 3.33-3.49 (m, 3H), 3.07-3.21 (m, 4H), 2.79 (s, 2H), 1.65 (br. s., 2H), 1.05-1.47 (m, 6H), 0.93 (t, J=7.40 Hz, 3H), 0.70-0.87 (m, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 561.2.

Example 30

2-[[6-Amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl-pyrrolidine-1-carboxylate

The title compound was prepared in analogy to step 6 of method A from Example 1, substituting 2-[chlorocarbonyl(methyl)amino]ethyl pyrrolidine-1-carboxylate (intermediate BF) for N-methyl-N-propyl carbamoyl chloride (intermediate AA). 2-[[6-Amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methyl amino]ethyl pyrrolidine-1-carboxylate (10.0 mg; the compound from Example 30) was obtained as a yellow solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.26-7.41 (m, 5H), 6.96 (br.s., 2H), 4.99 (s, 2H), 4.01-4.35 (m, 4H), 3.29-3.47 (m, 3H), 3.23 (br. s., 3H), 3.03-3.17 (m, 4H), 1.52-1.84 (m, 6H), 0.90-0.96 (m, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 545.2.

Example 31

2-[[6-Amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl-N-methyl-N-propylcarbamate

The title compound was prepared in analogy to step 6 of method A from Example 1, substituting 2-[chlorocarbonyl(methyl)amino]ethyl N-methyl-N-propylcarbamate (intermediate BG) for N-methyl-N-propylcarbamoyl chloride (intermediate AA). 2-[[6-Amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methyl-amino]ethyl N-methyl-N-propylcarbamate (3.7 mg; the compound from Example 31) was obtained as a yellow solid. ¹ H-NMR (400 MHz, CD ₃ OD) δ ^ppm : 7.22-7.48 (m, 5H), 5.09-5.22 (m, 4H), 4.55 (s, 2H), 3.38-3.57 (m, 4H), 3.13 (s, 3H), 1.61-1.85 (m, 4H), 1.22-1.41 (m, 3H), 0.88-1.13 (m, 6H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 547.2.

Example 32

2-[[6-Amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl-N,N-diethylcarbamate

The title compound was prepared in analogy to step 6 of method A from Example 1, substituting 2-[chlorocarbonyl(methyl)amino]ethyl N,N-diethylcarbamate (intermediate BH) for N-methyl-N-propylcarbamoyl chloride (intermediate AA). 2-[[6-Amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methylamino]ethyl N,N-diethylcarbamate (21.7 mg; the compound from Example 32) was obtained as a yellow solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.25-7.41 (m, 5H), 6.96 (br. s., 2H), 4.99 (s, 2H), 4.08-4.36 (m, 3H), 3.70 (br. 1H), 3.33-3.46 (m, 3H), 3.01-3.24 (m, 7H), 1.55-1.74 (m, 2H), 0.86-1.05 (m, 9H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 547.2.

Example 33

2-[[6-Amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]-methyl-amino]ethyl-ethyl carbonate

The title compound was prepared in analogy to step 6 of method A from Example 1, substituting 2-[chlorocarbonyl(methyl)amino]ethyl ethyl carbonate (intermediate BI) for N-methyl-N-propylcarbamoyl chloride (intermediate AA). 2-[[6-Amino-9-benzyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carbonyl]methyl-amino]ethyl ethyl carbonate (46 mg; the compound from Example 33) was obtained as a yellow solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 0.82-0.99 (m, 3H), 1.02-1.28 (m, 3H), 1.56-1.76 (m, 2H), 3.05-3.18 (m, 3H), 3.35-3.48 (m, 3H), 3.73 (t, J=5.08 Hz, 2H), 4.08-4.27 (m, 3H), 4.37 (br. s., 1H), 5.00 (s, 2H), 6.76-7.11 (m, 2H), 7.22-7.45 (m, 5H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 520.

Example 34-A and Example 34-B

6-Amino-N-butyl-9-[(4-chlorophenyl)methyl]-N-methyl-8-oxo-2-[S(S)-propylsulfonimidoyl]purine-7-carboxamide and 6-amino-N-butyl-9-[(4-chlorophenyl)methyl]-N-methyl-8-oxo-2-[S(S)-propylsulfonimidoyl]purine-7-carboxamide

Step 1. Preparation of 4-amino-3-[(4-chlorophenyl)methyl]-2-oxo-1H-imidazole-5-carbonitrile (compound 34a)

Compound 34a was prepared in analogy to step 1 of method A of Example 1, using 4-chlorobenzylisocyanate instead of benzyl isocyanate. 4-Amino-3-[(4-chlorophenyl)methyl]-2-oxo-1H-imidazole-5-carbonitrile (8.0 g; compound 34a) was obtained as a yellow solid. MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 249.

Step 2. Preparation of 6-amino-9-[(4-chlorophenyl)methyl]-2-sulfanyl-7H-purin-8-one (compound 34b)

Compound 34b was prepared in analogy to step 2 of method A of Example 1, substituting 4-amino-3-[(4-chlorophenyl)methyl]-2-oxo-1H-imidazole-5-carbonitrile (compound 34a) for 4-amino-3-phenylmethyl-2-oxo-1H-imidazole-5-carbonitrile (compound 1a). 6-Amino-9-[(4-chlorophenyl)methyl]-2-sulfanyl-7H-purin-8-one (6.4 g; compound 34b) was obtained as a yellow solid and used in the next step without further purification. MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 308.

Step 3. Preparation of 6-amino-9-[(4-chlorophenyl)methyl]-2-propylsulfanyl-7H-purin-8-one (compound 34c)

Compound 34c was prepared in analogy to step 3 of method A of Example 1, substituting 6-amino-9-[(4-chlorophenyl)methyl]-2-sulfanyl-7H-purin-8-one (compound 34b) for 6-amino-9-phenylmethyl-2-sulfanyl-7H-purin-8-one (compound 1b). 6-Amino-9-[(4-chlorophenyl)methyl]-2-propylsulfanyl-7H-purin-8-one (800 mg; compound 34c) was obtained as a white solid. MS: found (ESI ⁺ ) [(M + H) ⁺ ]: 350.

Step 4. Preparation of 6-amino-9-[(4-chlorophenyl)methyl]-2-propylsulfinyl-7H-purin-8-one (compound 34d)

Compound 34d was prepared in analogy to step 4 of method A from Example 1, substituting 6-amino-9-[(4-chlorophenyl)methyl]-2-propylsulfanyl-7H-purin-8-one (compound 34c) for 6-amino-9-benzyl-2-propylsulfanyl-7H-purin-8-one (compound 1c). 6-Amino-9-[(4-chlorophenyl)methyl]-2-propylsulfinyl-7H-purin-8-one (150 mg; compound 34d) was obtained as a white solid. MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 366.

Step 5. Preparation of 6-amino-9-[(4-chlorophenyl)methyl]-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 34e), 6-amino-9-[(4-chlorophenyl)methyl]-2-[S(S)-propylsulfonimidoyl)-7H-purin-8-one and 6-amino-9-[(4-chlorophenyl)methyl]-2-[S(S)-propylsulfonimidoyl)-7H-purin-8-one (compounds 34e-A and compound 34e-B)

Compound 34e was prepared in analogy to step 5 of method A from Example 1, using 6-amino-9-[(4-chlorophenyl)methyl]-2-propylsulfinyl-7H-purin-8-one (compound 34d) instead of 6-amino-9-benzyl-2-(2-propylsulfinyl)-7H-purin-8-one (compound 1d). 6-Amino-9-[(4-chlorophenyl)methyl]-2-(propylsulfonimidoyl)-7H-purin-8-one (250 mg; compound 34e) was obtained as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 10.60 (br. s, 1H), 7.32-7.42 (m, 4H), 6.98 (br. s, 2H), 4.96 (s, 2H), 4.03 (s, 1H), 3.25-3.41 (m, 2H), 1.56-1.68 (m, 2H), 0.91 (t, J=8 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 381.

After separation of the chiral HPLC mixture representing compound 34e, compound 34e-A (faster eluting, 110 mg) and compound 34e-B (slower eluting, 100 mg) were obtained as a white solid using 5%-40% methanol with (0.05% DEA)/CO ₂ on a ChiralPak OJ-3 column.

Compound 34e-A: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 10.63 (br. s, 1H), 7.33-7.42 (m, 4H), 6.99 (br. s, 2H), 4.96 (s, 2H), 4.05 (br. s, 1H), 3.26-3.39 (m, 2H), 1.53-1.69 (m, 2H), 0.91 (t, J=7.4 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 381.

Compound 34e-B: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 10.63 (br. s, 1H), 7.33-7.42 (m, 4H), 6.99 (br. s, 2H), 4.96 (s, 2H), 4.05 (br. s, 1H), 3.26-3.40 (m, 2H), 1.54-1.69 (m, 2H), 0.91 (t, J=7.5 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 381.

Step 6. 6-Amino-N-butyl-9-[(4-chlorophenyl)methyl]-N-methyl-8-oxo-2-[S(S)-propylsulfonimidoyl]purine-7-carboxamide and 6-amino-N-butyl-9-[(4-chlorophenyl)methyl]-N-methyl-8-oxo-2-[S(S)-propylsulfonimidoyl]purine-7-carboxamide (the compound of Example 34-A and the compound of Example 34-B)

The compound of Example 34-A was prepared in analogy to step 6 of Method A of Example 1, using compound 34e-A and N-butyl-N-methyl-carbamoyl chloride instead of 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e) and N-methyl-N-propyl-carbamoyl chloride (intermediate AA).

Compound from Example 34-A (160 mg): ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.37-7.45 (m, 4H), 6.91 (br. s., 2H), 4.99 (s, 2H), 4.17 (s, 1H), 3.28-3.40 (m, 4H), 3.05 (s, 2H), 3.02 (s, 1H), 1.49-1.70 (m, 4H), 1.15-1.37 (m, 2H), 0.89-0.94 (m, 5H), 0.76 (t, J=8 Hz, 1H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 494.

The compound from Example 34-B (167 mg) was prepared in analogy to the compound from Example 34-A, using compound 34e-B instead of compound 34e-A.

Example 34-B compound: ¹ H NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.36-7.45 (m, 4H), 6.91 (br. s., 2H), 4.99 (s, 2H), 4.17 (s, 1H), 3.28-3.41 (m, 4H), 3.05 (s, 2H), 3.02 (s, 1H), 1.50-1.71 (m, 4H), 1.15-1.37 (m, 2H), 0.89-0.94 (m, 5H), 0.76 (t, J=7.4 Hz, 1H). MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 494.

Example 35

6-Amino-9-[(4-chlorophenyl)methyl]-N-ethyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide

The title compound was prepared in analogy to step 6 of method A from Example 1, substituting 6-amino-9-[(4-chlorophenyl)methyl]-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 34e) and N-ethyl-N-methylcarbamoyl chloride for 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e) and N-methyl-N-propylcarbamoyl chloride (intermediate AA). 6-Amino-9-[(4-chlorophenyl)methyl]-N-ethyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)purine-7-carboxamide (60 mg; the compound from Example 35) was obtained as a white solid. ¹ H NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.40 (s, 4H), 6.91 (br s, 2H), 4.99 (s, 2H), 4.16 (s, 1H), 3.34-3.44 (m, 4H), 3.05 (s, 2H), 3.01 (s, 1H), 1.58-1.67 (m, 2H), 1.18 (t, J=8.0 Hz, 3H), 0.92 (t, J=8.0 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 466.

Example 36-A and Example 36-B

6-Amino-N-methyl-8-oxo-N-propyl-2-[S(S)-propylsulfonimidoyl]-9-(p-tolylmethyl)purine-7-carboxamide and 6-amino-N-methyl-8-oxo-N-propyl-2-[S(R)-propylsulfonimidoyl]-9-(p-tolylmethyl)purine-7-carboxamide

Step 1. Preparation of 6-chloro-5-nitro-2-propylsulfanyl-N-(p-tolylmethyl)pyrimidin-4-amine (compound 36a)

Compound 36a was prepared in analogy to step 1 of method B of Example 1, using p-tolylmethylamine instead of phenylmethanamine. 6-Chloro-5-nitro-2-propylsulfanyl-N-(p-tolylmethyl)pyrimidin-4-amine (3.9 g; compound 36a) was obtained as a white solid. MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 353.

Step 2. Preparation of 6-chloro-2-propylsulfanyl-N4-(p-tolylmethyl)pyrimidine-4,5-diamine (compound 36b)

Compound 36b was prepared in analogy to step 2 of method B of Example 1, using 6-chloro-5-nitro-2-propylsulfanyl-N-(p-tolylmethyl)pyrimidin-4-amine (compound 36a) instead of N-benzyl-6-chloro-5-nitro-2-propylsulfanyl-pyrimidin-4-amine (compound 1f). 6-Chloro-2-propylsulfanyl-N4-(p-tolylmethyl)pyrimidine-4,5-diamine (2.2 g; compound 36b) was obtained as a white solid. MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 323.

Step 3. Preparation of 6-chloro-2-propylsulfanyl-9-(p-tolylmethyl)-7H-purin-8-one (compound 36c)

Compound 36c was prepared in analogy to step 3 of method B of Example 1, using 6-chloro-2-propylsulfanyl-N-4-(p-tolylmethyl)pyrimidine-4,5-diamine (compound 36b) instead of N-benzyl-6-chloro-2-(propylsulfanyl)pyrimidine-4,5-diamine (compound 1g). 6-Chloro-2-propylsulfanyl-9-(p-tolylmethyl)-7H-purin-8-one (2.2 g; compound 36c) was obtained as a white solid. MS: found (ESI+) [(M+H) ⁺ ]: 349.

Step 4. Preparation of 6-[(4-methoxyphenyl)methylamino]-2-propylsulfanyl-9-(p-tolylmethyl)-7H-purin-8-one (compound 36d)

Compound 36d was prepared in analogy to step 4 of method B of Example 1, substituting 6-chloro-2-propylsulfanyl-9-(p-tolylmethyl)-7H-purin-8-one (compound 36c) for 9-benzyl-6-chloro-2-propylsulfanyl-7H-purin-8-one (compound 1h). 6-[(4-Methoxyphenyl)methylamino]-2-propylsulfanyl-9-(p-tolylmethyl)-7H-purin-8-one (2.0 g; compound 36d) was obtained as a white solid. MS: found (ESI ⁺ ) [(M + H) ⁺ ]: 450.

Step 5. Preparation of 6-amino-2-propylsulfanyl-9-(p-tolylmethyl)-7H-purin-8-one (compound 36e)

Compound 36e was prepared in analogy to step 5 of method B of Example 1, substituting 6-[(4-methoxyphenyl)methylamino]-2-propylsulfanyl-9-(p-tolylmethyl)-7H-purin-8-one (compound 36d) for 6-amino-9-benzyl-2-propylsulfanyl-7H-purin-8-one (compound 1i). 6-Amino-2-propylsulfanyl-9-(p-tolylmethyl)-7H-purin-8-one (1.0 g; compound 36e) was obtained as a white solid. MS: found (ESI ⁺ ) [(M + H) ⁺ ]: 330.

Step 6. Preparation of 6-amino-2-propylsulfinyl-9-(p-tolylmethyl)-7H-purin-8-one (compound 36f)

Compound 36f was prepared in analogy to step 6 of method B of Example 1, substituting 6-amino-2-propylsulfanyl-9-(p-tolylmethyl)-7H-purin-8-one (compound 36e) for 6-amino-9-benzyl-2-(2-propylsulfanyl)-7H-purin-8-one (compound 1c). 6-Amino-2-propylsulfinyl-9-(p-tolylmethyl)-7H-purin-8-one (220 mg; compound 36f) was obtained as a white solid. MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 345.

Step 7. Preparation of 6-amino-2-(propylsulfonimidoyl)-9-(p-tolylmethyl)-7H-purin-8-one (compound 36g)

Compound 36g was prepared in analogy to step 7 of method B of Example 1, using 6-amino-2-propylsulfinyl-9-(p-tolylmethyl)-7H-purin-8-one (compound 36f) instead of 6-amino-9-benzyl-2-propylsulfinyl-7H-purin-8-one (compound 1d). 6-Amino-2-(propylsulfonimidoyl)-9-(p-tolylmethyl)-7H-purin-8-one (127 mg; compound 36g) was obtained as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 10.67 (br. s., 1H), 7.23 (d, J=8.0 Hz, 2H), 7.13 (d, J=8.0 Hz, 2H), 6.98 (br. s., 2H), 4.91 (s, 2H), 4.05 (s, 1H), 3.34-3.27 (m, 2H), 2.26 (s, 3H), 1.67-1.62 (m, 2H), 0.92 (t, J=8.0 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 361.

After separation of compound 36g by chiral HPLC, compound 36g-A (faster eluting; 50 mg) and compound 36g-B (slower eluting; 49 mg) were obtained as a white solid using 30% isopropanol with (0.05% DEA)/CO ₂ on a ChiralPakAD-3 column.

Compound 36g-A: ¹ H-NMR: (400 MHz, DMSO-d ₆ ) δ ^ppm : 10.51 (s, 1H), 7.22 (d, J=8.0 Hz, 2H), 7.12 (d, J=8.0 Hz, 2H), 7.00 (s, 2H), 4.91 (s, 2H), 4.03 (s, 1H), 3.35-3.31 (m, 2H), 2.26 (s, 3H), 1.70-1.58 (m, 2H), 0.93 (t, J=7.40 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 361.

Compound 36g-B: ¹ H-NMR: (400 MHz, DMSO-d ₆ ) δ ^ppm : 10.54 (s, 1H), 7.23 (d, J=8.0 Hz, 2H), 7.13 (d, J=8.0 Hz, 2H), 6.97 (s, 2H), 4.91 (s, 2H), 4.04 (s, 1H), 3.34-3.30 (m, 2H), 2.26 (s, 3H), 1.72-1.57 (m, 2H), 0.93 (t, J=7.40 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 361.

Step 8. Preparation of 6-amino-N-methyl-8-oxo-N-propyl-2-[S(S)-propylsulfonimidoyl]-9-(p-tolylmethyl)purine-7-carboxamide and 6-amino-N-methyl-8-oxo-N-propyl-2-[S(R)-propylsulfonimidoyl]-9-(p-tolylmethyl)purine-7-carboxamide (compounds from Example 36-A and compound from Example 36-B)

The compound of Example 36-A was prepared in analogy to step 6 of method A of Example 1, using compound 36g-A instead of 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e). The compound of Example 36-A (108 mg) was obtained as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.27 (d, J=8 Hz, 2H), 7.14 (d, J=8 Hz, 2H), 6.87 (br. s., 2H), 4.95 (s, 2H), 4.15 (s, 1H), 3.33-3.57 (m, 4H), 3.05 (s, 2H), 3.02 (s, 1H), 2.26 (s, 3H), 1.52-1.73 (m, 4H), 0.75-0.97 (m, 6H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 460.

The compound of Example 36-B was prepared in analogy to step 6 of Method A of Example 1, using compound 36g-B instead of 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e). Example 36-B compound (125 mg): ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.27 (d, J=8 Hz, 2H), 7.14 (d, J=8 Hz, 2H), 6.87 (br. s., 2H), 4.95 (s, 2H), 4.15 (s, 1H), 3.33-3.57 (m, 4H), 3.05 (s, 2H), 3.02 (s, 1H), 2.26 (s, 3H), 1.52-1.73 (m, 4H), 0.75-0.97 (m, 5H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 460.

Example 37-A and Example 37-B

6-Amino-2-[S(S)-propylsulfonimidoyl]-9-(p-tolylmethyl)-7-(pyrrolidine-1-carbonyl)purin-8-one and 6-amino-2-[S(R)-propylsulfonimidoyl]-9-(p-tolylmethyl)-7-(pyrrolidine-1-carbonyl)purin-8-one

The compound of Example 37-A was prepared in analogy to step 6 of method A of Example 1, using compound 36g-A and pyrrolidine-1-carbonyl chloride instead of 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e) and N-methyl-N-propyl carbamoyl chloride (intermediate AA).

The compound from Example 37-A (390 mg) was obtained as a white solid. ¹ H NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.31-7.11 (m, 4H), 7.04 (s, 2H), 4.95 (s, 2H), 4.15 (s, 1H), 3.65-3.47 (m, 4H), 3.37 (m, 2H), 2.27 (s, 3H), 1.97-1.81 (m, 4H), 1.71-1.59 (m, 2H), 0.94 (t, J=7.4 Hz, 3H). MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 458.2.

The compound from Example 37-B (125 mg) was prepared in analogy to the compound from Example 37-A using compound 36g-B instead of compound 36g-A. ¹ H NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.28-7.14 (m, 4H), 7.04 (s, 2H), 4.95 (s, 2H), 4.15 (s, 1H), 3.65-3.47 (m, 4H), 3.37 (m, 2H), 2.27 (s, 3H), 1.93-1.84 (m, 4H), 1.65-1.60 (m, 2H), 0.95 (t, J=7.4 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 458.3.

Example 38-A and Example 38-B 6-Amino-N-(2-methoxyethyl)-N-methyl-8-oxo-2-[S(S)-propylsulfonimidoyl]-9-(p-tolylmethyl)purine-7-carboxamide and 6-amino-N-(2-methoxyethyl)-N-methyl-8-oxo-2-[S(S)-propylsulfonimidoyl]-9-(p-tolylmethyl)purine-7-carboxamide

The compound of Example 38-A was prepared in analogy to step 6 of method A of Example 1, using compound 36g-A and N-(2-methoxyethyl)-N-methylcarbamoyl chloride (intermediate AB) instead of 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e) and N-methyl-N-propylcarbamoyl chloride (intermediate AA).

The compound from Example 38-A (57.8 mg) was obtained as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.26 (d, J=7.6 Hz, 2H), 7.14 (d, J=7.6 Hz, 2H), 6.89-6.78 (m, 2H), 4.95 (s, 2H), 4.18 (s, 1H), 3.62-3.58 (m, 2H), 3.43-3.37 (m, 2H), 3.30-3.10 (m, 3H), 3.09-3.08 (m, 3H), 3.08-3.05 (m, 2H), 2.27 (s, 3H), 1.77-1.54 (m, 2H), 0.95 (t, J=7.4 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 476.3.

The compound from Example 38-B (46.6 mg) was prepared in analogy to the compound from Example 38-A, using compound 36g-B instead of compound 36g-A. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.26 (d, J=7.6 Hz, 2H), 7.14 (d, J=7.6 Hz, 2H), 6.89-6.78 (m, 2H), 4.95 (s, 2H), 4.18 (s, 1H), 3.62-3.58 (m, 2H), 3.43-3.37 (m, 2H), 3.30-3.10 (m, 3H), 3.09-3.08 (m, 3H), 3.08-3.05 (m, 2H), 2.27 (s, 3H), 1.77-1.54 (m, 2H), 0.95 (t, J=7.4 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 476.3.

Example 39

6-Amino-N-ethyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)-9-(p-tolylmethyl)purine-7-carboxamide

The title compound was prepared in analogy to step 6 of method A from Example 1, substituting N-ethyl-N-methylcarbamoyl chloride and 6-amino-2-(propylsulfonimidoyl)-9-(p-tolylmethyl)-7H-purin-8-one (compound 36g) for N-methyl-N-propylcarbamoyl chloride (intermediate AA) and 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e). 6-Amino-N-ethyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)-9-(p-tolylmethyl)-purine-7-carboxamide (141.8 mg; the compound from Example 39) was obtained as a light yellow solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.26 (d, J=7.9 Hz, 2H), 7.15 (d, J=7.9 Hz, 2H), 6.89 (s, 2H), 4.95 (s, 2H), 4.24-4.07 (m, 1H), 3.52-3.35 (m, 4H), 3.10-2.95 (m, 3H), 2.26 (s, 3H), 1.77-1.55 (m, 2H), 1.24-1.10 (m, 3H), 0.95 (t, J=7.4 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 446.1.

Example 40

6-Amino-N-butyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)-9-(p-tolylmethyl)purine-7-carboxamide

The title compound was prepared in analogy to step 6 of method A from Example 1, substituting 6-amino-2-(propylsulfonimidoyl)-9-(p-tolylmethyl)-7H-purin-8-one (compound 36g) and N-butyl-N-methylcarbamoyl chloride for 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e) and N-methyl-N-propylcarbamoyl chloride (intermediate AA). 6-Amino-N-butyl-N-methyl-8-oxo-2-(propylsulfonimidoyl)-9-(p-tolylmethyl)purine-7-carboxamide (32 mg; Example 40) was obtained as a white solid. ¹ H NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.28-7.14 (m, 4H), 6.88 (s, 2H), 4.95 (s, 2H), 4.16 (s, 1H), 3.41-3.36 (m, 2H), 3.10-2.99 (m, 3H), 2.53-2.51 (m, 2H), 2.27 (s, 3H), 1.71-1.63 (m, 2H), 1.62-1.51 (m, 2H), 1.42-1.26 (m, 2H), 0.97-0.74 (m, 6H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 474.3.

Example 41-A and Example 41-B

6-Amino-9-[(4-chlorophenyl)methyl]-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide (the compound from Example 41-A) and 6-amino-9-[(4-chlorophenyl)methyl]-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide (the compound from Example 41-B)

Step 1. Preparation of 6-amino-9-[(4-chlorophenyl)methyl]-2-ethylsulfanyl-7H-purin-8-one (compound 41a)

Compound 41a was prepared in analogy to step 3 of method A from Example 1, using iodoethane and 6-amino-9-[(4-chlorophenyl)methyl]-2-sulfanyl-7H-purin-8-one (compound 34b) instead of bromopropane and 6-amino-9-phenylmethyl-2-sulfanyl-7H-purin-8-one (compound 1b). 6-Amino-9-[(4-chlorophenyl)methyl]-2-ethylsulfanyl-7H-purin-8-one (2.5 g; compound 41a) was obtained as a white solid. MS: found (ESI+) [(M+H) ⁺ ]: 336.

Step 2. Preparation of 6-amino-9-(4-chlorobenzyl)-2-ethylsulfinyl-7H-purin-8-one (compound 41b)

Compound 41b was prepared in analogy to step 4 of method A of Example 1, substituting 6-amino-9-[(4-chlorophenyl)methyl]-2-ethylsulfanyl-7H-purin-8-one (compound 41a) for 6-amino-9-benzyl-2-propylsulfanyl-7H-purin-8-one (compound 1c). 6-Amino-9-(4-chlorobenzyl)-2-ethylsulfinyl-7H-purin-8-one (1.94 g; compound 41b) was obtained as a white solid. MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 352.

Step 3. Preparation of 6-amino-9-[(4-chlorophenyl)methyl]-2-(ethylsulfonimidoyl)-7H-purin-8-one (compound 41c)

Compound 41c was prepared in analogy to step 4 of method A from Example 1, using 6-amino-9-(4-chlorobenzyl)-2-ethylsulfinyl-7H-purin-8-one (compound 41b) instead of 6-amino-9-benzyl-2-(2-methylsulfinyl)-7H-purin-8-one (compound 1d). 6-Amino-9-[(4-chlorophenyl)methyl]-2-(ethylsulfonimidoyl)-7H-purin-8-one (217 mg; the compound from Example 41c) was obtained as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 10.61 (s, 1H), 7.42-7.35 (m, 4H), 6.98 (s, 2H), 4.96 (s, 2H), 4.05 (s, 1H), 3.42-3.37 (m, 2H), 1.16 (t, J=7.4 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 367.0.

After separation of the chiral HPLC mixture representing compound 41c, compound 41c-A (faster eluting; 31.8 mg) and compound 41c-B (slower eluting; 10 mg) were obtained as a white solid using 5%-40% methanol with (0.05% DEA)/CO ₂ on a ChiralPak IC-3 column.

Compound 41с-А: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 10.76 (s, 1H), 7.45-7.33 (m, 4H), 7.01 (s, 2H), 4.96 (s, 2H), 4.03 (s, 1H), 3.40-3.34 (m, 2H), 1.17 (t, J=7.4 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 367.0.

Compound 41c-B: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 10.70 (s, 1H), 7.46-7.28 (m, 4H), 7.01 (s, 2H), 4.96 (s, 2H), 4.03 (s, 1H), 3.44-3.36 (m, 2H), 1.17 (t, J=7.4 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 367.0.

Step 4. 6-Amino-9-[(4-chlorophenyl)methyl]-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide (the compound from Example 41-A) and 6-amino-9-[(4-chlorophenyl)methyl]-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide (the compound from Example 41-B)

The compound of Example 41-A was prepared in analogy to Step 6 of Method A of Example 1, using compound 41c-B instead of 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e). 6-Amino-9-[(4-chlorophenyl)methyl]-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide (the compound of Example 41-A, 78 mg) was obtained as a white solid. ¹ H NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.43-7.41 (m, 4H), 6.90 (s, 2H), 5.00 (s, 2H), 4.19 (s, 1H), 3.46-3.39 (m, 2H), 3.39-3.38 (m, 2H), 3.09-2.99 (m, 3H), 1.69-1.52 (m, 2H), 1.19 (t, J=7.28 Hz, 3H), 0.95-0.66 (m, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 466.1.

The compound from Example 41-B (125 mg) was prepared in analogy to Step 6 of Method A of Example 1, using compound 41c-A instead of 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e). 6-Amino-9-[(4-chlorophenyl)methyl]-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide (the compound from Example 41-B, 38 mg) was obtained as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.43-7.41 (m, 4H), 6.90 (s, 2H), 5.00 (s, 2H), 4.20 (s, 1H), 3.46-3.41 (m, 2H), 3.40-3.39 (m, 2H), 3.10-3.00 (m, 3H), 1.69-1.50 (m, 2H), 1.24-1.12 (m, 3H), 0.93-0.73 (m, 3H). (MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 466.2.

The stereochemical conformation for the compound of Example 41-B was determined using single crystal X-ray diffraction as shown in Fig. 1.

Example 42-A and Example 42-B

6-Amino-9-[(4-chlorophenyl)methyl]-N-ethyl-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-purine-7-carboxamide (the compound from Example 42-A) and 6-amino-9-[(4-chlorophenyl)methyl]-N-ethyl-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-purine-7-carboxamide (the compound from Example 42-B)

The compound of Example 42-A was prepared in analogy to Step 6 of Method A of Example 1, substituting compound 41c-A and N-ethyl-N-methylcarbamoyl chloride for 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e) and N-methyl-N-propylcarbamoyl chloride (intermediate AA). 6-Amino-9-[(4-chlorophenyl)methyl]-N-ethyl-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-purine-7-carboxamide (the compound of Example 42-A, 40 mg) was obtained as a white solid. ¹ H NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.43-7.41 (m, 4H), 6.90 (s, 2H), 4.99 (s, 2H), 4.18 (s, 1H), 3.48-3.40 (m, 2H), 3.39 (s, 2H), 3.05-3.01 (m, 3H), 1.20-1.14 (m, 6H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 452.2.

The compound of Example 42-B was prepared in analogy to Step 6 of Method A of Example 1, substituting compound 41c-B and N-ethyl-N-methylcarbamoyl chloride for 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e) and N-methyl-N-propylcarbamoyl chloride (intermediate AA). 6-Amino-9-[(4-chlorophenyl)methyl]-N-ethyl-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-purine-7-carboxamide (the compound of Example 42-B, 38 mg) was obtained as a white solid. ¹ H NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.43-7.41 (m, 4H), 6.91 (s, 2H), 4.98 (s, 2H), 4.19 (s, 1H), 3.48-3.40 (m, 2H), 3.39 (s, 2H), 3.09-2.97 (m, 3H), 1.23-1.11 (m, 6H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 452.2.

The stereochemical conformation for the compound of Example 42-A was determined using single crystal X-ray diffraction as shown in Fig. 2.

Example 43-A and example 43-B

6-Amino-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-9-(p-tolylmethyl)purine-7-carboxamide (compound from Example 43-A) and 6-amino-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-9-(p-tolylmethyl)purine-7-carboxamide (compound from Example 43-B)

Step 1. Preparation of 4-amino-2-oxo-3-(p-tolylmethyl)-1H-imidazole-5-carbonitrile (compound 43a)

Compound 43a was prepared in analogy to step 1 of method A of Example 1, using 4-methylbenzyl isocyanate instead of benzyl isocyanate. 4-Amino-2-oxo-3-(p-tolylmethyl)-1H-imidazole-5-carbonitrile (26.6 g; compound 43a) was obtained as a gray solid and used directly in the next step without further purification. MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 229.2.

Step 2. Preparation of 6-amino-9-(p-tolylmethyl)-2-sulfanyl-7H-purin-8-one (compound 43b)

Compound 43b was prepared in analogy to step 2 of method A of Example 1, substituting 4-amino-2-oxo-3-(p-tolylmethyl)-1H-imidazole-5-carbonitrile (compound 43a) for 4-amino-3-benzyl-2-oxo-1H-imidazole-5-carbonitrile (compound 1a). 6-Amino-9-(p-tolylmethyl)-2-sulfanyl-7H-purin-8-one (20.0 g; compound 43b) was obtained as a yellow solid. MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 288.

Step 3. Preparation of 6-amino-2-ethylsulfanyl-9-(p-tolylmethyl)-7H-purin-8-one (compound 43c)

Compound 43c was prepared in analogy to step 3 of method A of Example 1, using 6-amino-9-(p-tolylmethyl)-2-sulfanyl-7H-purin-8-one (compound 43b) and iodoethane instead of 6-amino-9-benzyl-2-sulfanyl-7H-purin-8-one (compound 1b) and bromopropane. 6-Amino-2-ethylsulfanyl-9-(p-tolylmethyl)-7H-purin-8-one (13 g; compound 43c) was obtained as a yellow solid. MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 316.

Step 4. Preparation of 6-amino-2-ethylsulfinyl-9-(p-tolylmethyl)-7H-purin-8-one (compound 43d)

Compound 43d was prepared in analogy to step 4 of method A from Example 1, substituting 6-amino-2-ethylsulfanyl-9-(p-tolylmethyl)-7H-purin-8-one (compound 43c) for 6-amino-9-benzyl-2-methylsulfanyl-7H-purin-8-one (compound 1c). 6-Amino-2-ethylsulfinyl-9-(p-tolylmethyl)-7H-purin-8-one (3.5 g; compound 43d) was obtained as a yellow solid. MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 332.

Step 5. Preparation of 6-amino-2-(ethylsulfonimidoyl)-9-(p-tolylmethyl)-7H-purin-8-one (compound 43e)

Compound 43e was prepared in analogy to step 4 of method A from Example 1, using 6-amino-2-ethylsulfinyl-9-(p-tolylmethyl)-7H-purin-8-one (compound 43d) instead of 6-amino-9-benzyl-2-methylsulfinyl-7H-purin-8-one (compound 1d). 6-Amino-2-(ethylsulfonimidoyl)-9-(p-tolylmethyl)-7H-purin-8-one (530 mg; compound 43e) was obtained as a yellow solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 10.53 (s, 1H), 7.24 (d, J=8.03 Hz, 2H), 7.13 (d, J=8.03 Hz, 2H), 6.94 (br. s., 2H), 4.91 (s, 2H), 4.03 (s, 1H), 3.36-3.41 (m, 2H), 2.26 (s, 3H), 1.18 (t, J=7.28 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 347.

After separation of the chiral HPLC mixture representing compound 43e, compound 43e-A (faster eluting; 56.8 mg) and compound 43e-B (slower eluting; 56.7 mg) were obtained as a white solid using 5%-40% methanol with (0.05% DEA)/CO ₂ on a ChiralPak AD-3 column.

Compound 43e-A: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 10.52 (br. s., 1H), 7.23 (d, J=8.0 Hz, 2H), 7.13 (d, J=7.9 Hz, 2H), 6.94 (br. s., 2H), 4.90 (s, 2H), 4.03 (s, 1H), 3.42-3.33 (m, 2H), 2.25 (s, 3H), 1.17 (t, J=7.3 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 347.

Compound 43e-B: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 10.56 (br. s., 1H), 7.23 (d, J=8.0 Hz, 2H), 7.13 (d, J=8.0 Hz, 2H), 6.95 (br. s., 2H), 4.90 (s, 2H) 4.03 (s, 1H), 3.44-3.29 (m, 2H), 2.25 (s, 3H), 1.17 (t, J=7.3 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 347.

Step 6. Preparation of 6-amino-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-9-(p-tolylmethyl)purine-7-carboxamide (compounds from Example 43-A) and 6-amino-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-9-(p-tolylmethyl)purine-7-carboxamide (compounds from Example 43-B)

The compound from Example 43-A was prepared in analogy to step 6 of method A of Example 1, substituting compound 43e-A for 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e). 6-Amino-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-9-(p-tolylmethyl)purine-7-carboxamide (the compound from Example 43-A; 58.1 mg; faster eluting; 5% to 40% isopropanol with (0.05% DEA)/CO ₂ on a ChiralPak AD-3 column) was obtained as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.28 (d, J=7.8 Hz, 2H), 7.15 (d, J=7.8 Hz, 2H), 6.88 (br. s., 2H), 5.03-4.87 (m, 2H), 4.19 (s, 1H), 3.61-3.36 (m, 4H), 3.11-2.96 (m, 3H), 2.26 (s, 3H), 1.72-1.45 (m, 2H), 1.20 (t, J=7.2 Hz, 3H), 0.97-0.65 (m, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 446.

The compound of Example 43-B was prepared in analogy to step 6 of Method A of Example 1, using compound 43e-B instead of 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e). 6-Amino-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-9-(p-tolylmethyl)purine-7-carboxamide (the compound from Example 43-B; 40.1 mg; slower eluting, 5% to 40% isopropanol with (0.05% DEA)/CO ₂ on a ChiralPak AD-3 column) was obtained as a white solid: ¹ H NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.28 (d, J=7.5 Hz, 2H), 7.15 (d, J=7.5 Hz, 2H), 6.89 (br. s., 2H), 5.03-4.86 (m, 2H), 4.19 (s, 1H), 3.49-3.37 (m, 4H), 3.08-3.00 (m, 3H), 2.27 (s, 3H), 1.70-1.48 (m, 2H), 1.20 (t, J=7.2 Hz, 3H), 0.95-0.71 (m, 3H). MS: detected (ES ⁺ ) [(M+H) ⁺ ]: 446.3.

The stereochemical conformation for the compound of Example 43-B was determined using single crystal X-ray diffraction as shown in Fig. 3.

Example 44-A and example 44-B

6-Amino-N-ethyl-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-9-(p-tolylmethyl)purine-7-carboxamide (the compound from Example 44-A) and 6-amino-N-ethyl-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-9-(p-tolylmethyl)purine-7-carboxamide (the compound from Example 44-B)

The compound of Example 44-A was prepared in analogy to Step 6 of Method A of Example 1, substituting compound 43e-B and N-ethyl-N-methylcarbamoyl chloride for 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e) and N-methyl-N-propylcarbamoyl chloride (intermediate AA). 6-Amino-N-ethyl-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-9-(p-tolylmethyl)-purine-7-carboxamide (the compound of Example 44-A; 73.1 mg) was obtained as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.28 (d, J=7.8 Hz, 2H), 7.15 (d, J=7.8 Hz, 2H), 6.90 (br. s., 2H), 4.95 (s, 2H), 4.19 (br. s., 1H), 3.48-3.39 (m, 4H), 3.06-3.00 (m, 3H), 2.27 (s, 3H), 1.29-1.04 (m, 6H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 432.

The compound of Example 44-B was prepared in analogy to step 6 of Method A of Example 1, using compound 43e-A and N-ethyl-N-methyl-carbamoyl chloride instead of 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e) and N-methyl-N-propyl-carbamoyl chloride (intermediate AA).

6-Amino-N-ethyl-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-9-(p-tolylmethyl)-purine-7-carboxamide (the compound from Example 44-B; 46.7 mg) was obtained as a white solid: ¹ H NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.28 (d, J=7.9 Hz, 2H), 7.15 (d, J=7.9 Hz, 2H), 6.90 (br. s., 2H), 4.95 (s, 2H), 4.19 (br. s., 1H), 3.50-3.39 (m, 4H), 3.10-2.96 (m, 3H), 2.27 (s, 3H), 1.27-1.10 (m, 6H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 432.

Example 45-A and Example 45-B

6-Amino-2-[S(R)ethylsulfonimidoyl]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide and 6-amino-2-[S(S)-ethylsulfonimidoyl]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide

Step 1. Preparation of 4-amino-3-[(4-fluorophenyl)methyl]-2-oxo-1H-imidazole-5-carbonitrile (compound 45a)

Compound 45a was prepared in analogy to step 1 of method A from Example 1, using 4-fluorobenzylisocyanate instead of benzyl isocyanate. 4-Amino-3-[(4-fluorophenyl)methyl]-2-oxo-1H-imidazole-5-carbonitrile (48 g; compound 45a) was obtained as a light yellow solid and used directly in the next step without further purification. MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 233.

Step 2. Preparation of 6-amino-9-[(4-fluorophenyl)methyl]-2-sulfanyl-7H-purin-8-one (compound 45b)

Compound 45b was prepared in analogy to step 2 of method A of Example 1, substituting 4-amino-3-[(4-fluorophenyl)methyl]-2-oxo-1H-imidazole-5-carbonitrile (compound 45a) for 4-amino-3-phenylmethyl-2-oxo-1H-imidazole-5-carbonitrile (compound 1a). 6-Amino-9-[(4-fluorophenyl)methyl]-2-sulfanyl-7H-purin-8-one (32.0 g; compound 45b) was obtained as a yellow solid. MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 292.

Step 3. Preparation of 6-amino-2-ethylsulfanyl-9-[(4-fluorophenyl)methyl]-7H-purin-8-one (compound 45c)

Compound 45c was prepared in analogy to step 3 of method A of Example 1, using 6-amino-9-[(4-fluorophenyl)methyl]-2-sulfanyl-7H-purin-8-one (compound 45b) and iodoethane instead of 6-amino-9-benzyl-2-sulfanyl-7H-purin-8-one (compound 1b) and bromopropane. 6-Amino-2-ethylsulfanyl-9-[(4-fluorophenyl)methyl]-7H-purin-8-one (5.6 g; compound 45c) was obtained as a yellow solid. MS: found (ESI ⁺ ) [(M + H) ⁺ ]: 320.

Step 5. Preparation of 6-amino-2-ethylsulfinyl-9-[(4-fluorophenyl)methyl]-7H-purin-8-one (compound 45d)

Compound 45d was prepared in analogy to step 4 of method A from Example 1, substituting 6-amino-2-ethylsulfanyl-9-[(4-fluorophenyl)methyl]-7H-purin-8-one (compound 45c) for 6-amino-9-benzyl-2-propylsulfanyl-7H-purin-8-one (compound 1c). 6-Amino-2-ethylsulfinyl-9-[(4-fluorophenyl)methyl]-7H-purin-8-one (4.8 g; compound 45d) was obtained as a yellow solid. MS: found (ESI ⁺ ) [(M+H) ⁺ ]: 332.

Step 6. Preparation of 6-amino-2-(ethylsulfonimidoyl)-9-[(4-fluorophenyl)methyl]-7H-purin-8-one (compound 45e)

Compound 45e was prepared in analogy to step 4 of method A of Example 1, using 6-amino-2-ethylsulfinyl-9-[(4-fluorophenyl)methyl]-7H-purin-8-one (compound 45d) instead of 6-amino-9-benzyl-2-propylsulfinyl-7H-purin-8-one (compound 1d). 6-Amino-2-(ethylsulfonimidoyl)-9-[(4-fluorophenyl)methyl]-7H-purin-8-one (2.9 g; compound 45e) was obtained as a yellow solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 10.57 (br. s., 1H), 7.40 (dd, J=8.5; 5.5 Hz, 2H), 7.16 (t, J=8.9 Hz, 2H), 6.97 (br. s., 2H), 4.94 (s, 2H), 4.07 (s, 1H), 3.43-3.36 (m, 2H), 1.17 (t, J=7.4 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 351.

After separation of the chiral HPLC mixture representing compound 45e, compound 45e-A (faster eluting; 85.4 mg) and compound 45e-B (slower eluting; 36.4 mg) were obtained as a white solid using 5%-40% methanol with (0.05% DEA)/CO ₂ on a ChiralPak AD-3 column.

Compound 45e-A: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 10.53 (br. s., 1H), 7.41 (dd, J=8.5; 5.5 Hz, 2H), 7.17 (t, J=8.9 Hz, 2H), 6.98 (br. s., 2H), 4.95 (s, 2H), 4.07 (s, 1H), 3.45-3.36 (m, 2H), 1.17 (t, J=7.3 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 351.

Compound 45e-B: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 10.53 (br. s., 1H), 7.41 (dd, J=8.5; 5.5 Hz, 2H), 7.17 (t, J=8.9 Hz, 2H), 6.98 (br. s., 2H), 4.95 (s, 2H), 4.07 (s, 1H), 3.44-3.37 (m, 2H) 1.17 (t, J=7.3 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 351.

Step 7. Preparation of 6-amino-2-(ethylsulfonimidoyl)-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide (the compound of Example 45), 6-amino-2-[S(R)ethylsulfonimidoyl]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide, and 6-amino-2-[S(S)-ethylsulfonimidoyl]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide (the compound of Example 45-A and the compound of Example 45-B)

The compound of Example 45 was prepared in analogy to step 6 of method A of Example 1, substituting 6-amino-2-(ethylsulfonimidoyl)-9-[(4-fluorophenyl)methyl]-7H-purin-8-one (compound 45e) for 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e). 6-Amino-2-(ethylsulfonimidoyl)-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide (162.4 mg; the compound of Example 45) was obtained as a white solid.

After separation of the chiral HPLC mixture of the compound from Example 45, the compound from Example 45-A (faster eluting; 85.3 mg) and the compound from Example 45-B (slower eluting; 52 mg) were obtained as a white solid using 5%→40% methanol with (0.05% DEA)/CO ₂ on a ChiralPak AD-3 column.

Compound from example 45-A: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.53-7.38 (m, 2H), 7.18 (t, J=8.9 Hz, 2H), 6.90 (br.s., 2H), 4.99 (s, 2H), 4.21 (s, 1H), 3.48-3.37 (m, 4H), 3.10-3.01 (m, 3H), 1.69-1.49 (m, 2H), 1.25-1.14 (m, 3H), 0.94-0.72 (m, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 450.

Compound from Example 45-B: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.54-7.38 (m, 2H), 7.18 (t, J=8.9 Hz, 2H), 7.01-6.72 (m, 2H), 4.99 (s, 2H), 4.21 (s, 1H), 3.46-3.38 (m, 4H), 3.10-3.01 (m, 3H), 1.76-1.50 (m, 2H), 1.25-1.16 (m, 3H), 0.99-0.69 (m, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 450.

Example 46-A and example 46-B

6-Amino-N-ethyl-2-(ethylsulfonimidoyl)-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-purine-7-carboxamide (the compound of Example 46), 6-amino-N-ethyl-2-[S(S)-(ethylsulfonimidoyl)]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-purine-7-carboxamide and 6-amino-N-ethyl-2-[S(R)-(ethylsulfonimidoyl)]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-purine-7-carboxamide (the compound of Example 46-A and the compound of Example 46-B)

The compound of Example 46 was prepared in analogy to step 6 of method A of Example 1, substituting 6-amino-2-(ethylsulfonimidoyl)-9-[(4-fluorophenyl)methyl]-7H-purin-8-one (compound 45e) and N-ethyl-N-methylcarbamoyl chloride instead of 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e) and N-methyl-N-propylcarbamoyl chloride (intermediate AA). 6-Amino-N-ethyl-2-(ethylsulfonimidoyl)-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-purine-7-carboxamide (51 mg; the compound of Example 46) was obtained as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.46-7.43 (m, 2H), 7.20-7.15 (m, 2H), 6.90 (br. s., 2H), 4.98 (s, 2H), 4.18 (s, 1H), 3.47-3.32 (m, 4H), 3.05-3.01 (m, 3H), 1.21-1.14 (m, 6H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 436.

After separation of the chiral HPLC mixture of the compound from Example 46, the compound from Example 46-A (faster eluting; 72 mg) and the compound from Example 46-B (slower eluting; 45 mg) were obtained as a white solid using 5%→40% methanol with (0.05% DEA)/CO ₂ on a ChiralPak AD-3 column.

Compound from example 46-A: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.46-7.43 (m, 2H), 7.20-7.16 (m, 2H), 6.90 (br. s., 2H), 4.98 (s, 2H), 4.18 (s, 1H), 3.47-3.32 (m, 4H), 3.05-3.01 (m, 3H), 1.21-1.14 (m, 6H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 436.

Compound from example 46-B: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.46-7.43 (m, 2H), 7.20-7.14 (m, 2H), 6.92 (br. s., 2H), 4.98 (s, 2H), 4.20 (br. s., 1H), 3.47-3.32 (m, 4H), 3.05-3.01 (m, 3H), 1.23-1.19 (m, 6H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 436.

Example 47-A and example 47-B

6-Amino-9-[(4-bromophenyl)methyl]-2-(ethylsulfonimidoyl)-N-methyl-8-oxo-N-propyl-purine-7-carboxamide (the compound of Example 47), 6-amino-2-[S(R)-ethylsulfonimidoyl]-9-[(4-bromophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide and 6-amino-2-[S(S)-ethylsulfonimidoyl]-9-[(4-bromophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide

Step 1. Preparation of 4-amino-3-[(4-bromophenyl)methyl]-2-oxo-1H-imidazole-5-carbonitrile (compound 47a)

Compound 47a was prepared in analogy to step 1 of method A from Example 1, substituting 4-bromobenzyl isocyanate for benzyl isocyanate. 4-Amino-3-[(4-bromophenyl)methyl]-2-oxo-1H-imidazole-5-carbonitrile (500 mg; compound 47a) was obtained as a light yellow solid and used directly in the next step without further purification. ¹ H NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 9.94 (s, 1H), 7.55-7.53 (d, J=8.0 Hz, 2H), 7.20-7.18 (d, J=8.0 Hz, 2H), 6.52 (br. s., 2H), 4.74 (s, 2H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 293.

Step 2. Preparation of 6-amino-9-[(4-bromophenyl)methyl]-2-sulfanyl-7H-purin-8-one (compound 47b)

Compound 47b was prepared in analogy to step 2 of method A of Example 1, substituting 4-amino-3-[(4-bromophenyl)methyl]-2-oxo-1H-imidazole-5-carbonitrile (compound 47a) for 4-amino-3-phenylmethyl-2-oxo-1H-imidazole-5-carbonitrile (compound 1a). 6-Amino-9-[(4-bromophenyl)methyl]-2-sulfanyl-7H-purin-8-one (300 mg; compound 47b) was obtained as a yellow solid. MS: found (ESI ⁺ ) [(M + H) ⁺ ]: 352.

Step 3. Preparation of 6-amino-2-ethylsulfanyl-9-[(4-bromophenyl)methyl]-7H-purin-8-one (compound 47c)

Compound 47c was prepared in analogy to step 3 of method A from Example 1, using 6-amino-9-[(4-bromophenyl)methyl]-2-sulfanyl-7H-purin-8-one (compound 45b) and iodoethane instead of 6-amino-9-benzyl-2-sulfanyl-7H-purin-8-one (compound 1b) and bromopropane. 6-Amino-2-ethylsulfanyl-9-[(4-bromophenyl)methyl]-7H-purin-8-one (5.6 g; compound 47c) was obtained as a yellow solid. MS: found (ESI ⁺ ) [(M + H) ⁺ ]: 380.

Step 4. Preparation of 6-amino-9-[(4-bromophenyl)methyl]-2-ethylsulfinyl-7H-purin-8-one (compound 47d)

Compound 47d was prepared in analogy to step 6 of method B of Example 1, substituting 6-amino-9-[(4-bromophenyl)methyl]-2-ethylsulfanyl-7H-purin-8-one (compound 47c) for 6-amino-9-benzyl-2-(2-propylsulfanyl)-7H-purin-8-one (compound 1c). 6-Amino-9-[(4-bromophenyl)methyl]-2-ethylsulfinyl-7H-purin-8-one (3.2 g; compound 47d) was obtained as a white solid. MS: found (ESI ⁺ ) [(M + H) ⁺ ]: 396.

Step 5. Preparation of 6-amino-9-[(4-bromophenyl)methyl]-2-(ethylsulfonimidoyl)-7H-purin-8-one (compound 47e)

Compound 47e was prepared in analogy to step 7 of method B of Example 1, substituting 6-amino-9-[(4-bromophenyl)methyl]-2-ethylsulfinyl-7H-purin-8-one (compound 47d) for 6-amino-9-benzyl-2-propylsulfinyl-7H-purin-8-one (compound 1d). 6-Amino-9-[(4-bromophenyl)methyl]-2-(ethylsulfonimidoyl)-7H-purin-8-one (4.0 g; compound 47e) was obtained as a white solid. MS: found (ESI ⁺ ) [(M + H) ⁺ ]: 411.

After separation of the chiral HPLC mixture representing compound 47e, compound 47e-A (faster eluting; 112 mg) and compound 47e-B (slower eluting; 99 mg) were obtained as white solids using 5%→40% methanol with (0.05% DEA)/CO ₂ on a ChiralPak AD-3 column.

Compound 47e-A: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 10.58 (br. s., 1H), 7.52-7.54 (d, J=8.0 Hz, 2H), 7.31-7.29 (t, J=8.0 Hz, 2H), 6.54 (br. s., 2H), 4.93 (s, 2H), 4.05 (s, 1H), 3.42-3.31 (m, 2H), 1.15 (t, J=7.3 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 411.

Compound 47e-B: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 10.58 (br. s., 1H), 7.54-7.52 (d, J=8.0 Hz, 2H), 7.31-7.29 (t, J=8.0 Hz, 2H), 6.98 (br. s., 2H), 4.93 (s, 2H), 4.06 (s, 1H), 3.40-3.37 (m, 2H), 1.15 (t, J=7.3 Hz, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 411.

Step 6. Preparation of 6-amino-9-[(4-bromophenyl)methyl]-2-(ethylsulfonimidoyl)-N-methyl-8-oxo-N-propyl-purine-7-carboxamide (the compounds of Example 47), 6-amino-9-[(4-bromophenyl)methyl]-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide, and 6-amino-9-[(4-bromophenyl)methyl]-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide (the compounds of Example 47-A and the compound of Example 47-B)

The compound of Example 47 was prepared in analogy to step 6 of method A of Example 1, substituting 6-amino-9-[(4-bromophenyl)methyl]-2-(ethylsulfonimidoyl)-7H-purin-8-one (compound 47e) for 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e). 6-Amino-9-[(4-bromophenyl)methyl]-2-(ethylsulfonimidoyl)-N-methyl-8-oxo-N-propyl-purine-7-carboxamide (570 mg; the compound of Example 47) was obtained as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.56-7.53 (m, 2H), 7.36-7.34 (m, 2H), 6.92 (br. s., 2H), 4.97 (s, 2H), 4.18 (s, 1H), 3.45-3.38 (m, 4H), 3.05-3.02 (m, 3H), 1.65-1.56 (m, 2H), 1.19 (t, J=8.0 Hz, 3H), 0.93-0.75 (m, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 510.

After separation of the chiral HPLC mixture of the compound from Example 47, the compound from Example 47-A (faster eluting; 260 mg) and the compound from Example 47-B (slower eluting; 266 mg) were obtained as a white solid using 5%→40% methanol with (0.05% DEA)/CO ₂ on a ChiralPak AD-3 column.

Compound from Example 47-A: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.56-7.54 (d, J=8.0 Hz, 2H), 7.36-7.33 (d, J=8.0 Hz, 2H), 6.90 (br. s., 2H), 4.97 (s, 2H), 4.21 (s, 1H), 3.46-3.41 (m, 4H), 3.05-3.02 (m, 3H), 1.65-1.54 (m, 2H), 1.24-1.16 (m, 3H), 0.93-0.75 (m, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 510.

Compound from Example 47-B: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.54-7.53 (d, J=8.0 Hz, 2H), 7.36-7.33 (d, J=8.0 Hz, 2H), 6.90 (br. s., 2H), 4.97 (s, 2H), 4.21 (s, 1H), 3.46-3.41 (m, 4H), 3.06-3.02 (m, 3H), 1.65-1.54 (m, 2H), 1.20-1.16 (m, 3H), 0.93-0.75 (m, 3H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 510.

Example 48-A and example 48-B

6-Amino-9-[(4-bromophenyl)methyl]-N-ethyl-2-(ethylsulfonimidoyl)-N-methyl-8-oxo-purine-7-carboxamide (the compound of Example 48), 6-amino-9-[(4-bromophenyl)methyl]-N-ethyl-2-[S(S)-(ethylsulfonimidoyl)]-N-methyl-8-oxo-purine-7-carboxamide and 6-amino-9-[(4-bromophenyl)methyl]-N-ethyl-2-[S(R)-(ethylsulfonimidoyl)]-N-methyl-8-oxo-purine-7-carboxamide (the compound of Example 48-A and the compound of Example 48-B)

The compound of Example 48 was prepared in analogy to step 6 of method A of Example 1, substituting 6-amino-9-[(4-bromophenyl)methyl]-2-(ethylsulfonimidoyl)-7H-purin-8-one (compound 47e) and N-ethyl-N-methylcarbamoyl chloride for 6-amino-9-benzyl-2-(propylsulfonimidoyl)-7H-purin-8-one (compound 1e) and N-methyl-N-propylcarbamoyl chloride (intermediate AA). 6-Amino-9-[(4-bromophenyl)methyl]-2-(ethylsulfonimidoyl)-N-methyl-8-oxo-N-propylpurine-7-carboxamide (469 mg; the compound of Example 48) was obtained as a white solid. ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.56-7.54 (d, J=8.0 Hz, 2H), 7.36-7.34 (d, J=8.0 Hz, 2H), 6.98 (br. s., 2H), 4.97 (s, 2H), 3.53-3.46 (m, 4H), 3.05-3.01 (m, 3H), 1.22-1.16 (m, 6H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 496.

After separation of the chiral HPLC mixture of the compound from Example 48, the compound from Example 48-A (faster eluting; 198 mg) and the compound from Example 48-B (slower eluting; 202 mg) were obtained as a white solid using 5%→40% methanol with (0.05% DEA)/CO ₂ on a ChiralPak AD-3 column.

Compound from Example 48-A: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.56-7.54 (d, J=8.0 Hz, 2H), 7.36-7.34 (d, J=8.0 Hz, 2H), 6.92 (br. s., 2H), 4.97 (s, 2H), 4.19-4.18 (m, 1H), 3.46-3.41 (m, 4H), 3.05-3.01 (m, 3H), 1.20-1.14 (m, 6H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 496.

Compound from Example 48-B: ¹ H-NMR (400 MHz, DMSO-d ₆ ) δ ^ppm : 7.56-7.54 (d, J=8.0 Hz, 2H), 7.36-7.34 (d, J=8.0 Hz, 2H), 6.92 (br. s., 2H), 4.97 (s, 2H), 4.24 (br. s., 1H), 3.58-3.41 (m, 4H), 3.05-3.01 (m, 3H), 1.26-1.01 (m, 6H). MS: detected (ESI ⁺ ) [(M+H) ⁺ ]: 496.

Example 49

Activity of Compounds and Example Compounds in an Assay Using Human TLR-7-Bearing Human Embryonic Kidney Cells (HEK293-hTLR-7)

Assay using HEK293-Blue-hTLR-7 cells

The stable HEK293-Blue-hTLR-7 cell line was purchased from InvivoGen (catalog #: hkb-htlr7; San Diego, CA, USA). These cells were designed to study human TLR7 stimulation by monitoring NF-κB activation. The SEAP (secreted embryonic alkaline phosphatase) reporter gene was placed under the control of the minimal IFN-β promoter fused to five binding sites for NF-κB and AP-1 (activator protein 1). SEAP was induced by NF-κB and AP-1 activation by stimulation of HEK-Blue-hTLR7 cells with TLR7 ligands. Therefore, reporter expression was regulated by the NF-κB promoter after stimulation with human TLR7 for 20 h. SEAP reporter activity in cell culture supernatant was detected using the QUANTIBlue™ kit (Cat. No. rep-qb1; Invivogen, San Diego, CA, USA) at 640 nm containing detection medium that turned purple or blue in the presence of alkaline phosphatase.

HEK293-Blue-hTLR7 cells were incubated for 24 h at a density of 250,000-450,000 cells/mL in a volume of 180 μL in a 96-well plate in Dulbecco's modified Eagle's medium (DMEM) containing glucose (4.5 g/L), penicillin (50 U/mL), streptomycin (50 mg/mL), normocin (100 mg/mL), 2 mM L-glutamine, 10% (v/v) heat-inactivated fetal calf serum. Then, HEK293-Blue-hTLR-7 cells were incubated with 20 μl of the test compound solution taken in serial dilution in the presence of DMSO at a final concentration of 1% and incubated at 37°C in a _CO2 incubator for 20 h. Then, 20 μl of the supernatant from each well was incubated with 180 μl of Quantiblue substrate solution at 37°C for 2 h and the absorbance was measured at 620-655 nm using a spectrophotometer. The signal transduction pathway by which TLR7 activation leads to subsequent NF-κB activation is well recognized, and therefore a similar reporter gene assay has also been widely used to evaluate TLR7 agonist (Tsuneyasu Kaisho and Takashi Tanaka, Trends in Immunology, volume 29, issue 7, July 2008, pages 329.sci; Hiroaki Hemmi et al., Nature Immunology, 3, 196–200 (2002)).

The compounds and compounds of the Examples of the present invention were tested in an assay using HEK293-hTLR-7 cells for their TLR7 agonist activity as described herein and the results are shown in Table 1. The prodrugs of the Examples were found to have an EC ₅₀ of from about 2.1 μM to about 1000 μM, and the active forms of the compounds were found to have an EC ₅₀ of less than 0.2 μM. The calculated EC _50(prodrug) /EC _{50(active form)} ratios ranged from 32 to about 7600.

Example 50

Metabolism of prodrugs of the compound of formula (I)

A study was conducted to evaluate the metabolic conversion of prodrugs of the compound of formula (I) into their corresponding active form. The compounds of formula (I), provided that they function as prodrugs, can be metabolized in the body to the active compound or other compounds of the invention. Human liver microsomes are often used to evaluate the degree of metabolic conversion of prodrugs in the body of an animal or a human.

Materials

The NADPH cofactor system (reduced form of NADP), including β-nicotinamide adenine dinucleotide phosphate (NADP), isocitric acid, and isocitrate dehydrogenase, was purchased from Sigma-Aldrich Co. (St. Louis, MO, USA). Human liver microsomes (catalog #452117, lot #38290) were purchased from Corning (Woburn, MA, USA). Mouse liver microsomes (catalog #M1000, lot #1310028) were purchased from Xenotech.

Working solution of compounds and other solution

Compounds were dissolved in DMSO to prepare concentrated 10 mM solutions. 10 μl of the concentrated solution was diluted with acetonitrile (990 μl) to obtain a 100 μM working solution.

Incubation

Microsomes were pre-incubated with the test compound for 10 min at 37°C in 100 mM potassium phosphate buffer, pH 7.4. Reactions were initiated by adding the NADPH-regenerating system to obtain a final incubation volume of 200 μl, and the mixtures were shaken in a water bath at 37°C. Incubation mixtures contained liver microsomes (0.5 mg microsomal protein/ml), substrates (1.0 μM) and NADP (1 mM), isocitrate dehydrogenase (1 unit/ml), and isocitric acid (6 mM).

Preparation of samples for analysis

After 30 min, the reaction was quenched by adding 600 μL of cold acetonitrile (containing tolbutamide (100 ng/mL) and labetalol (100 ng/mL) as internal standard). Samples were centrifuged at 4000 rpm for 20 min and the resulting supernatants were subjected to LC-MS/MS analysis.

Samples for the calibration curve were prepared as follows. Liver microsomes (100 μl/well) and NADPH regenerating system solution (98 μl/well) were added to a 96-well plate. First, 600 μl of the quenching solution was added, followed by 2 μl of the standard curve solution and the working QC solution.

Biological analysis

Quantification of compounds was performed on an API4000 LC-MS/MS instrument with ESI in positive ion mode using multiple reaction monitoring (MRM).

A study was conducted to evaluate the metabolic conversion of prodrugs (1 μM), namely, the compounds of Example 1, Example 1-A, Example 1-B, Example 2, Example 2-A, Example 2-B, Example 3, Example 4, Example 5, Example 6, Example 7, Example 8, Example 9, Example 10, Example 11, Example 12, Example 13, Example 14, Example 15, Example 16, Example 17, Example 21, Example 22, Example 23, Example 25, Example 26, Example 27, Example 28, Example 29, Example 30, Example 31, Example 32, Example 33, Example 34-A, Example 34-B, Example 36-A, Example 36-B, Example 37-A, Example 37-B, Example 38-A, Example 38-B, Example 39, Example 40, Example 41, Example 41-A, Example 41-B, Example 42, Example 42-A, Example 42-B, Example 43, Example 43-A, Example 43-B, Example 44, Example 44-A, Example 44-B and Example 45-A, Example 46-A, Example 46-B, Example 47-A, Example 47-B, Example 48-A, Example 48-B, into the corresponding active forms, namely, Compound 1e, Compound 1e-A, Compound 1e-B, Compound 34e-A, Compound 34e-B, Compound 36g-A, Compound 36g-B, Compound 36g, Compound 41c, Compound 41c-B, Compound 41c-A, Compound 43e, Compound 43e-A, Compound 43e-B, Compound 45e-A, compound 45e-B, compound 47e-A and compound 47e-B, in the presence of human liver microsomes. The results are summarized and shown in Table 2.

Example 51

In vivo antiviral efficacy of compound from Example 43-A in AAV-HBV mouse model

Animal model

Pathogen-free male C57BL/6 mice aged 4–6 weeks were purchased from the Shanghai Laboratory Animal Center, Chinese Academy of Sciences (SLAC) and housed in an animal care facility in individually ventilated cages under temperature- and light-controlled conditions according to the guidelines of the Animal Care and Institution Committee. AAV-HBV virus was obtained from the Beijing FivePlus Molecular Medicine Institute (Beijing, China). The recombinant virus carries 1.3 copies of the HBV genome packaged in AAV capsids, serotype 8 (AAV8). C57BL/6 mice were injected via the tail vein with 200 μl of the recombinant virus preparation diluted in buffered saline. On day 14, mice were bled to measure HBV surface antigen (HBsAg) and HBV genomic DNA in serum, and animals were then randomized into groups according to these HBV biomarkers.

Measurement of HBV biomarkers

Serum HBsAg and HBeAg levels were measured using chemiluminescence immunoassay (CLIA) kits (Autobio Diagnostics Co., Ltd., Zhengzhou, China) according to the manufacturer's instructions. The lower limit of detection for HBsAg was 0.05 international units (IU)/mL. A 500-fold dilution of serum was used to obtain values within the linear range of the standard curve.

HBV DNA was extracted from serum using the MagNA Pure 96 DNA and Viral NA Small Volume Kit (Roche) following the manufacturer's instructions. DNA samples were analyzed by real-time quantitative PCR (qPCR) using a set of HBV-specific primers and probe to specifically amplify and detect a 128-base pair (bp) region of the HBV genome, starting from nucleotide 2969 to 3096. The primer and probe sequences were:

forward primer: AAGAAAAACCCCGCCTGTAA;

reverse primer: CCTGTTCTGACTACTGCCTCTCC;

HBV probe: 5'TAMRA-CCTGATGTGATGTTCTCCATGTTCAGC-BHQ2-3'.

Anti-HBsAg antibodies in serum were tested using anti-HBsAg CLIA kits (Autobio Diagnostics Co., Ltd., Zhengzhou, China) and mouse anti-immunoglobulin G (IgG) biotin-conjugated antibody (0.5 mg/mL) from Mabtech B Elispot. The anti-IgG-biotin conjugate was diluted in PBS (phosphate-buffered saline) to a final concentration of 1 μg/mL. 25 μL of the mouse anti-IgG solution was mixed with the serum samples in the wells of the antiHBs CLIA kit for 1-hour incubation. The plate was then washed and streptavidin-HRP (horseradish peroxidase) was added for a 1-hour incubation at room temperature. After repeating the washing step, CLIA Substrate A and B were mixed and 50 µl of this mixture was added to each well. After 5 minutes of incubation at room temperature, the plate was read on an Envision plate reader (PerkinElmer) to measure luminescence.

Research plan and results

A mouse model with high levels of expression of both HBV DNA and HBsAg was generated by inoculating C57BL/6 mice with a recombinant adeno-associated virus (AAV) carrying a replicating HBV genome (AAV-HBV). In the case of long-term HBV viremia and a fully competent immune system, the AAV-HBV mouse model was used to evaluate the antiviral efficacy of TLR7 agonists, following the study plan shown in Table 3.

Specifically, Groups 2 and 3 were orally administered the compound of Example 43-A at a dose of 10 mg/kg once every other day (QOD) and once a week (QW), respectively, while control Group 1 received vehicle only. At an administration volume of 10 mL/kg, a sample based on the compound of Example 43-A (1 mg/mL) was prepared as an adduct containing 2% Klucel brand LF, 0.5% TPGS (tocopheryl polyethylene glycol 1000 succinate), 0.09% methylparabens, 0.01% propylparabens in water. Throughout the study, animals were treated for a total of 42 days and were bled twice a week from the submandibular vein to obtain serum. Serum samples were analyzed for HBV biomarkers.

As shown in Fig. 4, treatment with the compound of Example 43-A at 10 mg/kg QOD resulted in a dramatic reduction in HBV DNA (>3 log) and HBsAg (>2.8 log) levels. By the end of the 42-day treatment, the levels of these viral markers were undetectable and below the lower limit of quantification (LLOQ). Even at less frequent dosing on a QW schedule, administration of the compound of Example 43-A significantly reduced both HBV DNA (>2 log) and HBsAg (>2.8 log) levels. In addition, treatment with the compound of Example 43-A at 10 mg/kg, regardless of administration on a QOD or QW schedule, induced the production of antibodies to HBsAg to a significant level. In conclusion, the compound from Example 43-A demonstrated good anti-HBV activity in vivo, reducing the level of HBV viral markers and stimulating the production of HBV-specific antibodies.

Example 52

In vivo antiviral efficacy of compound from Example 41-A in AAV-HBV mouse model

The antiviral efficacy of the compound of Example 41-A was assessed in the same AAV-HBV model following the study design outlined in Table 4, with the same methods for measuring HBV biomarkers as described in Example 51.

Specifically, Groups 2, 3, and 4 were orally administered the compound of Example 41-A at doses of 1, 3, and 10 mg/kg QOD, respectively. Group 5 was treated at 10 mg/kg QW, while Group 1 received vehicle only. At a dose volume of 10 mL/kg, a sample of the compound of Example 41-A (0.1, 0.3, and 1 mg/mL) was prepared as an adduct containing 2% Klucel brand LF, 0.5% TPGS, 0.09% methylparabens, 0.01% propylparabens in water. Animals were treated for a total of 42 days throughout the study and were bled twice weekly from the submandibular vein to obtain serum. Serum samples were analyzed for HBV biomarkers.

As shown in Fig. 5, treatment with the compound of Example 41-A at doses of 1, 3, and 10 mg/kg QOD reduced HBV DNA and HBsAg levels in a dose-dependent manner. By the end of the 42-day treatment, all three doses were able to reduce the levels of these viral markers to levels below or close to the LLOQ. Even at less frequent dosing on a QW schedule, administration of the compound of Example 41-A at a dose of 10 mg/kg also reduced HBV DNA and HBsAg levels to undetectable levels by the end of treatment. In addition, treatment with the compound of Example 41-A induced the production of antibodies to HBsAg to significantly higher levels than the diluent treatment. In conclusion, the compound of Example 41-A demonstrated good anti-HBV activity in vivo, reducing the level of HBV viral markers and stimulating the production of HBV-specific antibodies.

Example 53

In vivo antiviral efficacy of compound from Example 42-A in AAV-HBV mouse model

The antiviral efficacy of the compound of Example 42-A was assessed in the same AAV-HBV model following the study design outlined in Table 5, with the same methods for measuring HBV biomarkers as described in Example 51.

Specifically, Groups 2, 3, and 4 were orally administered the compound of Example 42-A at doses of 1, 3, and 10 mg/kg QOD, respectively, while Group 1 received vehicle only. At a dose volume of 10 mL/kg, a sample of the compound of Example 42-A (0.1, 0.3, and 1 mg/mL) was prepared as an adduct containing 2% Klucel brand LF, 0.5% TPGS, 0.09% methylparabens, 0.01% propylparabens in water. Animals were treated for a total of 42 days throughout the study and were bled twice weekly from the submandibular vein to obtain serum. Serum samples were analyzed for HBV biomarkers.

As shown in Fig. 6, treatment with the compound of Example 42-A at doses of 1, 3 and 10 mg/kg QOD was effective in reducing HBV DNA and HBsAg levels in all cases. Although the higher doses promoted faster clearance of HBV DNA and HBsAg, by the end of the 42-day treatment, all three doses were able to reduce the levels of these viral markers to levels below or close to the LLOQ. Significantly high levels of anti-HBsAg antibodies were observed in all groups treated with the compound of Example 42-A. In conclusion, the compound of Example 42-A demonstrated good anti-HBV activity in vivo, reducing the level of HBV viral markers and stimulating the production of HBV-specific antibodies.

Example 54

In vivo antiviral efficacy of compound from Example 41-B in AAV-HBV mouse model

The antiviral efficacy of the compound from Example 41-B was assessed in the same AAV-HBV model following the study design outlined in Table 6, with the same methods for measuring HBV biomarkers as described in Example 51.

Specifically, Groups 2, 3, and 4 were orally administered the compound of Example 41-B at doses of 1, 3, and 10 mg/kg QOD, respectively, while Group 1 received vehicle only. At a dose volume of 10 mL/kg, a sample of the compound of Example 42-A (0.1, 0.3, and 1 mg/mL) was prepared as an adduct containing 2% Klucel brand LF, 0.5% TPGS, 0.09% methylparabens, 0.01% propylparabens in water. Animals were treated for a total of 42 days throughout the study and were bled twice weekly from the submandibular vein to obtain serum. Serum samples were analyzed for HBV biomarkers.

As shown in Fig. 7, treatment with the compound of Example 41-B at doses of 1, 3 and 10 mg/kg QOD was effective in reducing HBV DNA and HBsAg levels in all cases. By the end of the 42-day treatment, all three doses were able to reduce the levels of these viral markers to levels below the LLOQ. High levels of anti-HBsAg antibodies were observed in all groups treated with the compound of Example 41-B compared to the group receiving the vehicle. In conclusion, the compound of Example 41-B demonstrated anti-HBV activity in vivo, reducing the level of HBV viral markers and stimulating the production of HBV-specific antibodies.

Example 55

Single-dose PK study in male Wister-Han rats

To evaluate the pharmacokinetic properties of the test compounds, a single dose PK study was performed in male Wister-Han rats. Two groups of animals were administered the respective compound via oral gavage (OGW). Blood samples (approximately 20 µl) were collected via the jugular vein or from an alternate site at 15 min, 30 min, 1 h, 2 h, 4 h, 7 h and 24 h after dosing the groups. The blood samples were placed in tubes containing EOTA (ethylenediaminetetraacetic acid) _-K2 anticoagulant and centrifuged at 5000 rpm for 6 min at 4°C to obtain plasma from the samples. After centrifugation, the obtained plasma was transferred to fresh tubes for bioassay of both the prodrug and the active form by LC/MS/MS. In the prodrug-administered groups, the concentration of prodrugs in plasma samples was below the detection limit. The "Test compound" in Table 8 was used as the internal standard for the in vivo study of the metabolite (active form) of the "administered compound". The pharmacokinetic parameters were calculated using the non-compartmental analysis module of WinNonlin® Professional 6.2 software. The maximum concentration (C _max ) was recorded directly from the experimental observations. The area under the plasma concentration-time curve (AUC _0-t ) was calculated using the linear trapezoidal rule up to and including the last detectable concentration.

C _max and AUC _0-last are two important PK parameters related to the in vivo efficacy of the test compound. Compounds with higher C _max and AUC _0-last values will have better in vivo efficacy. The results obtained for the PK parameters after oral administration of the active forms and competitor compounds are summarized in Table 7. The PK parameters for prodrugs are summarized in Table 8.

After oral administration of the prodrugs, the presence of active forms was observed in the blood plasma and therefore they were tested. The exemplified prodrugs of the present invention (compounds of Examples 41-B, 42-A, 42-B, 43-A, 45-A and 45-B) unexpectedly showed many-fold higher C _max (5- to 175-fold increase) and AUC _0-last (2.5- to 56-fold increase) values compared to the reference compounds (GS9620, S-2 and S-3) and the compounds mentioned in the present invention (compounds 41c-A, 41c-B and 43e-A), all of which are active forms. These results clearly demonstrated the unexpected superiority of the prodrugs over the active forms in PK parameters, resulting in better in vivo efficacy.

Example 56

Solubility study using LYSA

The LYSA (lyophilized solubility assay) assay is used to determine the aqueous solubility of test compounds. Samples were prepared in duplicate from a 10 mM stock solution in DMSO. After evaporation of DMSO using a centrifugal vacuum evaporator, the compounds were dissolved in 0.05 M phosphate buffer (pH 6.5), stirred for one hour, and shaken for two hours. After one night, the solutions were filtered using a microtiter filter plate. The filtrate and a 1/10 dilution of the same were then analyzed using HPLC with ultraviolet detection (HPLC-UV). In addition, dilutions were prepared from 10 mM stock solutions to obtain a four-point calibration curve and used to determine the solubility of the compounds. The results are expressed as μg/mL. When the percentage of sample measured in solution after evaporation divided by the calculated maximum amount of sample exceeded 80%, the solubility was said to exceed this value.

The LYSA results are shown in Table 9. It was clear that the solubility of the active forms was unexpectedly increased by a factor of 10 to more than 200 when converted into various prodrugs.

Example 57

Portal Vein Study The aim of this study was to understand whether the prodrug remains unchanged when absorbed through the intestine into the portal circulation and to demonstrate the primary site where the conversion occurs.

Surgical procedure of portal vein cannulation (PVC) and carotid artery cannulation (CAC)

The operation was performed under pentobarbital/isoflurane anesthesia. Briefly, after disinfection of the peritoneal area with betadine and 70% isopropyl alcohol, a small abdominal midline incision was made. The cecum was retracted, the mesenteric vein was identified, and approximately 5 mm of the vessel was isolated. A loose ligature was placed proximally and the distal end of the vein was ligated. A small incision (just large enough to allow catheter insertion) was made in the isolated vein and a polyurethane (PU) catheter was inserted towards the liver to an appropriate length. The catheter was secured in place by tying the loose ligature around the cannulated vessel. The cecum was replaced into the peritoneal cavity. A hole was made in the right abdominal wall to allow free passage of the catheter tip. The catheter was secured to the abdominal wall with suture material. The abdominal muscle incision was closed using suture material. A small incision was made in the scapular region to serve as the exit site for the catheter. The catheter was tunneled subcutaneously and brought out through the scapular incision. A fixation suture was placed in the scapular region. The patency of the catheter was checked and then it was brought out of the subcutaneous space into the dorsal region of the neck. After gently wiping the surface, the abdominal cavity was closed. The left carotid artery was then cannulated using a PE50 polyethylene catheter. Both catheters were temporarily brought to the surface of the body, firmly fixed in the dorsal region of the neck and immobilized. The animals were then left in their cages to recover and used for research for at least 3 days after surgery. To maintain patency, all catheters were flushed once a day with a strong stream using heparinized saline.

Oral PK study in rats with dual PVC/CAC cannulation

Animals were fasted overnight (n=3) and then given compounds (10 mg/kg, 10 ml/kg) orally via gavage. Blood samples (60 μl) were collected simultaneously from the portal vein and carotid artery catheters at 0.083; 0.25; 0.5; 1, 2, 4, 7, 24 h. All blood samples were transferred to microcentrifuge tubes containing 2 μl of _K2 -EDTA (0.5 M) as an anticoagulant and placed on natural ice. Blood samples were then processed by centrifugation at approximately 4°C, 3000 g for 0.5 h to obtain plasma. Blood plasma samples should be stored in polypropylene tubes, quickly frozen on dry ice and at -70±10°C until LC/MS/MS analysis.

Pharmacokinetic parameters (mean ± standard deviation (SD), n=3) were determined and analyzed for the prodrugs and active forms in portal vein and carotid artery samples following oral administration of the prodrugs (10 mg/kg) to portal vein-cannulated rats. The results of testing the compounds of Examples 1-B, 41-A, 41-B, 42-A, and 43-A are summarized below.

Based on the above results, it was concluded that the primary site of prodrug conversion was likely the liver rather than the intestine, since the AUC _active /AUC _total ratio was higher in carotid artery samples compared to AUC _active /AUC _total in portal vein samples.

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SEQUENCE LIST

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Claims (38)

A method for stimulating the production of HBV-specific antibodies using a compound selected from: 6-amino-9-benzyl-N-methyl-8-oxo-N-propyl-2-(propylsulfonimidoyl)purine-7-carboxamide 6-amino-9-[(4-chlorophenyl)methyl]-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide 6-amino-9-[(4-chlorophenyl)methyl]-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide 6-amino-9-[(4-chlorophenyl)methyl]-N-ethyl-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-purine-7-carboxamide 6-amino-9-[(4-chlorophenyl)methyl]-N-ethyl-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-purine-7-carboxamide 6-amino-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-9-(p-tolylmethyl)purine-7-carboxamide 6-amino-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-N-propyl-9-(p-tolylmethyl)purine-7-carboxamide 6-amino-N-ethyl-2-[S(S)-ethylsulfonimidoyl]-N-methyl-8-oxo-9-(p-tolylmethyl)purine-7-carboxamide 6-amino-N-ethyl-2-[S(R)-ethylsulfonimidoyl]-N-methyl-8-oxo-9-(p-tolylmethyl)purine-7-carboxamide 6-amino-2-(ethylsulfonimidoyl)-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide 6-amino-2-[S(R)-ethylsulfonimidoyl]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide 6-amino-2-[S(S)-ethylsulfonimidoyl]-9-[(4-fluorophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide 6-amino-9-[(4-bromophenyl)methyl]-2-(ethylsulfonimidoyl)-N-methyl-8-oxo-N-propyl-purine-7-carboxamide 6-amino-2-[S(R)-ethylsulfonimidoyl]-9-[(4-bromophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide 6-amino-2-[S(S)-ethylsulfonimidoyl]-9-[(4-bromophenyl)methyl]-N-methyl-8-oxo-N-propyl-purine-7-carboxamide 6-Amino-9-[(4-bromophenyl)methyl]-N-ethyl-2-(ethylsulfonimidoyl)-N-methyl-8-oxo-purine-7-carboxamide 6-amino-9-[(4-bromophenyl)methyl]-N-ethyl-2-[S(S)-(ethylsulfonimidoyl)]-N-methyl-8-oxo-purine-7-carboxamide 6-amino-9-[(4-bromophenyl)methyl]-N-ethyl-2-[S(R)-(ethylsulfonimidoyl)]-N-methyl-8-oxo-purine-7-carboxamide or their pharmaceutically acceptable salts, enantiomers or diastereomers.