Production of P2X3 antagonists

Abstract

Described herein is a process for the synthesis of a P2X3 antagonist, wherein the P2X3 antagonist is methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1) or a pharmaceutically acceptable salt or co-crystal thereof.

Description

[Technical Field]

[0001] P2X purinergic receptors are a family of ion channels activated by extracellular adenosine triphosphate (ATP). Purinergic receptors are involved in a variety of biological functions. The P2X3 receptor subunit is a member of this family. It was originally cloned from rat dorsal root ganglia (Chen et al., Nature, vol. 377, pp. 428-431 (1995)). The nucleotide and amino acid sequences of rat and human P2X3 are now known (Lewis, et al., Nature, vol. 377, pp. 432-435 (1995); and Garcia-Guzman, et al., Brain Res. Mol. Brain Res., vol. 47, pp. 59-66 (1997)). Summary of the Invention

[0002] Described herein is a process for the synthesis of a P2X3 antagonist, wherein the P2X3 antagonist is methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1) or a pharmaceutically acceptable salt or co-crystal thereof. Various intermediates described herein can be prepared according to the methods disclosed in WO2021 / 161109 and WO2023 / 021328.

[0003] One embodiment described herein is a process for preparing methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), comprising: A) A compound having the following structure: [ka] and 2,2,6,6-tetramethylpiperidine 1-oxyl or T3P, which has the following structure: [ka] reacting with; B) Then, a compound having the following structure: [ka] with a mixture of potassium carbonate and potassium bicarbonate or potassium phosphate to produce a compound of the following structure: [ka] to get; C) Then, a compound of the following structure: [ka] with palladium on carbon and hydrogen to produce a compound of the following structure: [ka] to get; D) Then, a compound of the following structure: [ka] with hydrogen chloride in ethyl acetate to give a compound of the following structure: [ka] to get; E) Then, a compound of the following structure: [ka] with methyl chloroformate and aqueous sodium bicarbonate to give a compound of the following structure: [ka] to get; F) Then, a compound of the following structure: [ka] with carbonyldiimidazole and methylamine or methylamine hydrochloride to give a compound of the following structure: [ka] to get; G) Then, a compound of the following structure: [ka] with N-bromosuccinimide and trifluoromethanesulfonic acid to give a compound of the following structure: [ka] to get; H) Then, a compound of the following structure: [ka] with 4-methylpyridin-2-amine to produce a compound of the following structure: [ka] to get; The method includes:

[0004] One embodiment described herein is a process for preparing methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), comprising: A) A compound of the following structure: [ka] with toluenesulfonyl chloride and triethylamine to give a compound of the following structure: [ka] to get; B) Then, a compound of the following structure: [ka] with dimethyl malonate, potassium iodide, and cesium carbonate to give a compound of the following structure: [ka] to get; C) Then, a compound of the following structure: [ka] with triethylamine / magnesium chloride to give a compound of the following structure: [ka] to get; D) Then, a compound of the following structure: [ka] with lithium chloride and acetic acid to produce a compound of the following structure: [ka] to get; E) Then, a compound of the following structure: [ka] with aqueous sodium hydroxide to produce a compound of the following structure: [ka] to get; F) Then, a compound of the following structure: [ka] with hydrogen chloride in ethyl acetate to give a compound of the following structure: [ka] to get; G) Then, a compound of the following structure: [ka] with methyl chloroformate and aqueous sodium bicarbonate to give a compound of the following structure: [ka] to get; H) Then, a compound of the following structure: [ka] with carbonyldiimidazole and methylamine or methylamine hydrochloride to give a compound of the following structure: [ka] to get; I) Then, a compound of the following structure: [ka] with N-bromosuccinimide and trifluoromethanesulfonic acid to give a compound of the following structure: [ka] to get; J) Then, a compound of the following structure: [ka] with 4-methylpyridin-2-amine to produce a compound of the following structure: [ka] to get; The method includes:

[0005] Another embodiment described herein is methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1): [ka] 1. A method for preparing a compound of the following structure: [ka] and 4-methylpyridin-2-amine in the presence of a solvent. In some embodiments, the solvent is selected from acetonitrile and acetonitrile-containing water.

[0006] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with a brominating reagent. In some embodiments, the brominating reagent is N-bromosuccinimide. In some embodiments, the brominating reagent is CuBr. In some embodiments, the brominating reagent is N-bromosuccinimide in the presence of an acid. In some embodiments, the acid is trifluoromethanesulfonic acid. In some embodiments of the method for preparing methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound of the following structure: [ka] However, a compound having the following structure: [ka] with a brominating reagent. In some embodiments, the solvent is DCM.

[0007] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with an amide coupling reagent and methylamine or a salt of methylamine. In some embodiments, the amide coupling reagent is carbonyldiimidazole. In some embodiments, the amide coupling reagent is propanephosphonic anhydride (T3P). In some embodiments of the method for preparing methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with an amide coupling reagent and methylamine or a salt of methylamine in the presence of a solvent and optionally in the presence of a base. In some embodiments, the solvent is THF. In some embodiments, the base is N,N-diisopropylethylamine (DIPEA).

[0008] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with an amide coupling reagent and methylamine or a salt of methylamine. In some embodiments, the amide coupling reagent is carbonyldiimidazole. In some embodiments, the amide coupling reagent is propanephosphonic anhydride (T3P).

[0009] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with a brominating reagent. In some embodiments, the brominating reagent is N-bromosuccinimide. In some embodiments, the brominating reagent is CuBr. In some embodiments, the brominating reagent is N-bromosuccinimide in the presence of an acid. In some embodiments, the acid is trifluoromethanesulfonic acid.

[0010] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with methyl chloroformate and a base. In some embodiments, the base is aqueous sodium bicarbonate.

[0011] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with a deprotecting reagent selected from 1) hydrogen chloride in the presence of a solvent, 2) trifluoroacetic acid, and 3) phosphoric acid. In some embodiments, the deprotecting reagent is hydrogen chloride in the presence of a solvent, and the solvent is ethyl acetate. In some embodiments, the deprotecting reagent is trifluoroacetic acid. In some embodiments, the deprotecting reagent is phosphoric acid.

[0012] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with a hydrogenation catalyst and hydrogen. In some embodiments, the hydrogenation catalyst is palladium on carbon, palladium hydroxide, rhodium on carbon, rhodium on alumina, platinum oxide, or platinum on carbon. In some embodiments, the hydrogenation catalyst is palladium on carbon.

[0013] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] and a compound of the following structure: [ka] with a base. In some embodiments, the base is a mixture of aqueous potassium bicarbonate and potassium carbonate. In some embodiments, the base is potassium phosphate.

[0014] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with an oxidizing reagent. In some embodiments, the oxidizing reagent is selected from 2,2,6,6-tetramethylpiperidine 1-oxyl, T3P, and trichloroisocyanuric acid (TCCA). In some embodiments, the oxidizing reagent is 2,2,6,6-tetramethylpiperidine 1-oxyl. In some embodiments, the oxidizing reagent is T3P. In some embodiments, the oxidizing reagent is trichloroisocyanuric acid (TCCA).

[0015] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with a base in a solvent. In some embodiments, the base is aqueous sodium hydroxide. In some embodiments, the solvent is selected from tetrahydrofuran, N-methyl-2-pyrrolidone, methanol, isopropanol, and tert-butanol. In some embodiments, the solvent is isopropanol.

[0016] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with lithium chloride and acetic acid.

[0017] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] and a compound of the following structure: [ka] with a base in the presence of a solvent. In some embodiments, the base is selected from sodium hydride, lithium bis(trimethylsilyl)amide, potassium tert-butoxide, and triethylamine / magnesium chloride. In some embodiments, the base is triethylamine / magnesium chloride. In some embodiments, the solvent is tetrahydrofuran or 2-methyltetrahydrofuran. In some embodiments, the solvent is 2-methyltetrahydrofuran.

[0018] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with dimethyl malonate, potassium iodide, and a base. In some embodiments, the base is selected from sodium hydride, lithium bis(trimethylsilyl)amide, sodium bis(trimethylsilyl)amide, potassium bis(trimethylsilyl)amide, potassium carbonate, sodium carbonate, and cesium carbonate. In some embodiments, the base is cesium carbonate.

[0019] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with toluenesulfonyl chloride and a base in the presence of a solvent. In some embodiments, the base is triethylamine. In some embodiments, the solvent is dichloromethane.

[0020] Further disclosed herein is a compound having the structure: [ka] or a pharmaceutically acceptable salt thereof or a cocrystal thereof.

[0021] Further disclosed herein is a compound having the structure: [ka] or a pharmaceutically acceptable salt thereof or a cocrystal thereof.

[0022] Further disclosed herein is a compound having the structure: [ka] or a pharmaceutically acceptable salt thereof.

[0023] Incorporation by Reference All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.

[0024] Good manufacturing practices are usually required for large-scale production of clinically useful drug candidates. Provided herein are specific processes and methods for the production of the P2X3 antagonist methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1) or its pharmaceutically acceptable salt or co-crystal.

[0025] definition As used in this specification and the appended claims, the following terms have the meanings indicated below unless otherwise specified.

[0026] As used in this specification and the appended claims, the singular forms "a," "and," and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, reference to an "agent" includes a plural of such agents, and reference to a "cell" includes reference to one or more cells (or cells) and equivalents thereof.

[0027] When ranges are used herein for physical properties, such as molecular weight, or chemical properties, such as chemical formula, all combinations and subcombinations of ranges and specific embodiments are intended to be included.

[0028] The term "about" when referring to a numerical value or numerical range means that the stated numerical value or numerical range is an approximation within experimental variation (or within statistical experimental error), such that the numerical value or numerical range varies between 1% and 15% of the stated numerical value or numerical range.

[0029] The term "comprising" (and related terms such as "comprise" or "comprises" or "having" or "including") is not intended to exclude certain other embodiments, such as those that "consist of" or "consist essentially of" the recited features, such as any of the compositions, methods, or processes described herein.

[0030] The term "subject" or "patient" encompasses mammals and non-mammals. Examples of mammals include, but are not limited to, any member of the mammalian class (humans, non-human primates such as chimpanzees, other apes and monkeys; livestock such as cows, horses, sheep, goats, and pigs; domestic animals such as rabbits, dogs, and cats; laboratory animals including rodents such as rats, mice, and guinea pigs, etc.). Examples of non-mammals include, but are not limited to, birds, fish, and the like. In one embodiment of the methods and compositions provided herein, the mammal is a human.

[0031] As used herein, "treatment" or "treating," or "palliative" or "amelioration," are used interchangeably. These terms refer to an approach to achieving a beneficial or desired result, including, but not limited to, therapeutic benefit and / or prophylactic benefit. "Therapeutic benefit" refers to the eradication or amelioration of the underlying disease being treated. A therapeutic benefit is also achieved by eradicating or ameliorating one or more physiological symptoms associated with the underlying disease, such that the patient experiences improvement even though the patient still suffers from the underlying disease. For prophylactic benefit, the composition is administered to a patient at risk of developing a particular disease or who, despite having been diagnosed with the disease, still experiences one or more physiological symptoms of the disease.

[0032] " Pharmaceutically acceptable salt " includes both acid and base addition salts. Any one of the pharmaceutically acceptable salts of the compounds described herein is intended to include any pharmaceutically suitable salt form. The preferred pharmaceutically acceptable salts of the compounds described herein are pharmaceutically acceptable acid addition salts and pharmaceutically acceptable base addition salts.

[0033] "Pharmaceutically acceptable acid addition salts" refers to salts formed with inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, hydroiodic acid, hydrofluoric acid, phosphoric acid, and the like, which retain the biological effectiveness and properties of the free bases and which are not biologically or otherwise undesirable. Also included are salts formed with organic acids such as aliphatic mono- and dicarboxylic acids, phenyl-substituted alkanoic acids, hydroxyalkanoic acids, alkanedioic acids, aromatic acids, aliphatic and aromatic sulfonic acids (e.g., acetic acid, trifluoroacetic acid, propionic acid, glycolic acid, pyruvic acid, oxalic acid, maleic acid, malonic acid, succinic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, cinnamic acid, mandelic acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, salicylic acid, and the like). Thus, exemplary salts include sulfate, pyrosulfate, bisulfate, sulfite, bisulfite, nitrate, phosphate, monohydrogenphosphate, dihydrogenphosphate, metaphosphate, pyrophosphate, chloride, bromide, iodide, acetate, trifluoroacetate, propionate, caprylate, isobutyrate, oxalate, malonate, succinate, suberate, sebacate, fumarate, maleate, mandelate, benzoate, chlorobenzoate, methylbenzoate, dinitrobenzoate, phthalate, benzenesulfonate, toluenesulfonate, phenylacetate, citrate, lactate, malate, tartrate, methanesulfonate, and the like. Also contemplated are salts of amino acids such as arginate, gluconate, galacturonate, and the like (see, e.g., Berge SM et al., "Pharmaceutical Salts," Journal of Pharmaceutical Science, 66:1-19 (1997)). Acid addition salts of basic compounds are prepared by contacting the free base form with a sufficient amount of the desired acid to produce the salt.

[0034] "Pharmaceutically acceptable base addition salts" refer to salts that retain the biological effectiveness and properties of the free acid and are not biologically or otherwise undesirable. These salts are prepared by the addition of an inorganic or organic base to the free acid. In some embodiments, pharmaceutically acceptable base addition salts are formed with metals or amines, such as alkali and alkaline earth metals or organic amines. Salts derived from inorganic bases include, but are not limited to, sodium, potassium, lithium, ammonium, calcium, magnesium, iron, zinc, copper, manganese, aluminum, and the like salts. Salts derived from organic bases include, but are not limited to, salts of primary, secondary, and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines, basic ion exchange resins (e.g., 2-dimethylaminoethanol, 2-diethylaminoethanol, dicyclohexylamine, lysine, arginine, histidine, caffeine, procaine, N,N-dibenzylethylenediamine, chloroprocaine, hydrabamine, choline, betaine, ethylenediamine, ethylenedianiline, N-methylglucamine, glucosamine, methylglucamine, theobromine, purines, piperazine, piperidine, N-ethylpiperidine, polyamine resins, and the like). See Berge et al., supra.

[0035] As used herein, the term "pharmaceutical combination" refers to a product resulting from the mixing or combining of two or more active ingredients, and includes both fixed and non-fixed combinations of active ingredients. The term "fixed combination" means that both active ingredients are administered to a patient simultaneously in the form of a single entity or dosage. The term "non-fixed combination" means that the active ingredients are administered to a patient as separate entities simultaneously, concurrently, or sequentially, with no specific time limit between them, such that effective levels of the two compounds are achieved in the patient's body. The latter also applies to cocktail therapy, e.g., the administration of three or more active ingredients.

[0036] As used herein, "co-administration" and like terms are meant to encompass the administration of selected therapeutic agents to a single patient and are intended to include treatment regimens in which the agents are administered by the same or different routes of administration or at the same or different times.

[0037] The term "activator" is used herein to refer to any molecular species that results in activation of a receptor of interest, whether the molecular species itself binds to the receptor or a metabolite of that molecular species binds to the receptor when the molecular species is administered locally. Thus, an activator can be a ligand for the receptor, or it can be an activator that is metabolized to a ligand for the receptor, i.e., a metabolite formed in the tissue that becomes the actual ligand.

[0038] As used herein, the term "antagonist" refers to a small molecule agent that binds to a nuclear hormone receptor and subsequently reduces agonist-induced transcriptional activity of the nuclear hormone receptor.

[0039] As used herein, the term "agonist" refers to a small molecule agent that binds to a nuclear hormone receptor and subsequently increases the transcriptional activity of the nuclear hormone receptor in the absence of a known agonist.

[0040] As used herein, the term "inverse agonist" refers to a small molecule drug that binds to a nuclear hormone receptor and subsequently reduces the baseline level of nuclear hormone receptor transcriptional activity present in the absence of a known agonist.

[0041] As used herein, the term "modulate" means to interact directly or indirectly with a target protein so as to alter the activity of the target protein, including, by way of example only, inhibiting the activity of the target protein or limiting or reducing the activity of the target protein.

[0042] As used herein, the term "modulator" refers to a compound that changes the activity of a target. For example, a modulator can cause an increase or decrease in the magnitude of a specific activity of a target compared to the magnitude of the activity in the absence of the modulator. In certain embodiments, a modulator is an inhibitor, which reduces the magnitude of one or more activities of a target. In certain embodiments, an inhibitor completely blocks one or more activities of a target.

[0043] compound In some embodiments, the P2X3 antagonist described herein is methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1) or a pharmaceutically acceptable salt or co-crystal thereof. Compound 1 has the following structure: [ka] It has.

[0044] In some embodiments, an intermediate in the synthesis of Compound 1 is: [ka] is. In some embodiments, an intermediate in the synthesis of Compound 1 is: [ka] is. In some embodiments, an intermediate in the synthesis of Compound 1 is: [ka] is.

[0045] Further compounds The compounds described herein may exist as diastereomers, enantiomers, or other stereoisomeric forms in some cases. The compounds presented herein include all diastereomeric, enantiomeric, and epimeric forms, as well as the appropriate mixtures thereof. Separation of stereoisomers can be carried out by chromatography, or by forming diastereomers and separating them by recrystallization, chromatography, or a combination thereof (Jean Jacques, Andre Collet, Samuel H. Wilen, "Enantiomers, Racemates and Resolutions", John Wiley and Sons, Inc., 1981, the disclosure of which is incorporated herein by reference). Stereoisomers can also be obtained by stereoselective synthesis.

[0046] In some situations, compounds may exist as tautomers, and all tautomers are included in the formulae provided herein.

[0047] Pharmaceutically acceptable salts In some embodiments, the compounds described herein are present as their pharmaceutically acceptable salts. In some embodiments, the methods disclosed herein include methods of treating diseases by administering such pharmaceutically acceptable salts. In some embodiments, the methods disclosed herein include methods of treating diseases by administering such pharmaceutically acceptable salts as pharmaceutical compositions.

[0048] In some embodiments, the compounds described herein possess acidic or basic groups and thus react with any of a number of inorganic or organic bases and inorganic and organic acids to form pharmaceutically acceptable salts. In some embodiments, these salts are prepared in situ during the final isolation and purification of the compounds of the invention, or by separately reacting the purified compound in free form with the appropriate acid or base and isolating the salt thus formed.

[0049] In some embodiments, the pharmaceutically acceptable salt of Compound 1 is acetate, benzoate, besylate, tartrate, carbonate, citrate, fumarate, gluconate, hydrobromide, hydrochloride, maleate, mesylate, nitrate, phosphate, salicylate, succinate, sulfate, or tartrate. In some embodiments, the pharmaceutically acceptable salt of Compound 1 is a monohydrochloride salt. In further embodiments, the pharmaceutically acceptable salt of Compound 1 is a monohydrochloride salt.

[0050] solvate In some embodiments, the compounds described herein exist as solvates. The present invention provides methods of treating diseases by administering such solvates. The present invention further provides methods of treating diseases by administering such solvates as pharmaceutical compositions.

[0051] Solvates contain stoichiometric or non-stoichiometric amounts of a solvent and, in some embodiments, are formed during crystallization using a pharmaceutically acceptable solvent, such as water or ethanol. Hydrates are formed when the solvent is water, and alcoholates are formed when the solvent is alcohol. Solvates of the compounds described herein are conveniently prepared or formed during the processes described herein. By way of example only, hydrates of the compounds described herein are conveniently prepared by recrystallization from an aqueous / organic solvent mixture using organic solvents, including, but not limited to, dioxane, tetrahydrofuran, or methanol. Furthermore, the compounds provided herein exist in unsolvated as well as solvated forms. In general, solvated forms are considered equivalent to unsolvated forms for the purposes of the compounds and methods provided herein.

[0052] labeled compound In some embodiments, the compounds described herein exist in isotopically labeled form. In some embodiments, the methods disclosed herein include methods of treating a disease by administering such isotopically labeled compounds. In some embodiments, the methods disclosed herein include methods of treating a disease by administering such isotopically labeled compounds as pharmaceutical compositions. Thus, in some embodiments, the compounds disclosed herein include isotopically labeled compounds, which are identical to the compounds described herein except that one or more atoms have been replaced with an atom having an atomic mass or mass number different from that normally found in nature. Examples of isotopes that may be incorporated into the compounds of the present invention include isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur, fluorine, and chloride, respectively. 2 H, 3 H, 13 C. 14 C. l5 N, 18 O. 17 O. 31 P, 32 P, 35 S, 18 F and36 Cl, etc. Compounds described herein and their pharmaceutically acceptable salts, esters, solvates, hydrates, or derivatives that contain the aforementioned isotopes and / or isotopes of other atoms are within the scope of the present invention. Certain isotopically labeled compounds, e.g. 3 H and 14 Compounds incorporating radioactive isotopes such as C are useful in drug and / or substrate tissue distribution assays. 3 H) and carbon-14 isotopes (i.e. 14 C) is particularly preferred because of its ease of preparation and detection. 2 Substitution with heavy isotopes such as H provides certain therapeutic advantages resulting from greater metabolic stability, e.g., increased in vivo half-life or reduced required dosage. Increased levels of deuterium incorporation can produce a detectable kinetic isotope effect (KIE) and affect the pharmacokinetic, pharmacological, and / or toxicological parameters of Compound 1 compared to Compound 1 having naturally occurring levels of deuterium. In some embodiments, the isotopically labeled compound or a pharmaceutically acceptable salt thereof is prepared by any suitable method.

[0053] In some embodiments, at least one hydrogen of Compound 1 is replaced with deuterium.

[0054] In some embodiments, the compounds described herein are labeled by other means, including, but not limited to, the use of chromophores or fluorescent moieties, bioluminescent labels, or chemiluminescent labels.

[0055] Manufacturing method In some embodiments, synthesis of the compounds described herein is accomplished using means described in the chemical literature, using methods described herein, or a combination thereof. Additionally, solvents, temperatures, and other reaction conditions presented herein may be varied.

[0056] In other embodiments, the starting materials and reagents used in the synthesis of the compounds described herein are synthesized or obtained from commercial sources (for example, but not limited to, Sigma-Aldrich, FischerScientific (Fischer Chemicals), and AcrosOrganics). In further embodiments, the compounds described herein, and other related compounds with different substituents, can be synthesized using techniques and materials described herein, as well as art-recognized techniques and materials (e.g., Fieser and Fieser's Reagents for Organic Synthesis, Volumes 1-17 (John Wiley and Sons, 1991); Rodd's Chemistry of Carbon Compounds, Volumes 1-5 and Supplementals (Elsevier Science Publishers, 1989); Organic Reactions, Volumes 1-40 (John Wiley and Sons, 1991), Larock's Comprehensive Organic Transformations (VCH Publishers Inc., 1989), Advanced Organic Chemistry 4 (March, 1994), and others). th Ed., (Wiley 1992); Carey and Sundberg, Advanced Organic Chemistry 4 th Ed., Vols. A and B (Plenum 2000, 2001), and Green and Wuts, Protective Groups in Organic Synthesis 3 rdEd., (Wiley 1999), the disclosures of which are incorporated herein by reference in their entirety. General methods for preparing compounds as disclosed herein can be derived from reactions which can be modified by the use of appropriate reagents and conditions for the introduction of various moieties found in the formulae as provided herein.

[0057] In some embodiments, methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1): [ka] 1. A method for preparing a compound of the following structure: [ka] with 4-methylpyridin-2-amine in the presence of a solvent. In some embodiments, the solvent is selected from acetonitrile and acetonitrile-containing water. In some embodiments, the solvent is acetonitrile. In some embodiments, the solvent is acetonitrile. In some embodiments, the solvent is acetonitrile-containing water.

[0058] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with a brominating reagent. In some embodiments, the brominating reagent is N-bromosuccinimide in the presence of an acid. In some embodiments, the brominating reagent is copper(II) bromide.

[0059] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with an amide coupling reagent and methylamine or a salt of methylamine. In some embodiments, the amide coupling reagent is carbonyldiimidazole. In some embodiments, the amide coupling reagent is propanephosphonic anhydride (T3P).

[0060] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with an amide coupling reagent and methylamine or a salt of methylamine. In some embodiments, the amide coupling reagent is carbonyldiimidazole. In some embodiments, the amide coupling reagent is propanephosphonic anhydride (T3P).

[0061] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with a brominating reagent. In some embodiments, the brominating reagent is N-bromosuccinimide in the presence of an acid. In some embodiments, the acid is trifluoromethanesulfonic acid. In some embodiments, the brominating reagent is copper(II) bromide. In some embodiments, the brominating reagent is liquid bromine.

[0062] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with methyl chloroformate and a base. In some embodiments, the base is aqueous sodium bicarbonate.

[0063] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with a deprotecting reagent selected from 1) hydrogen chloride in the presence of a solvent, 2) trifluoroacetic acid, and 3) phosphoric acid. In some embodiments, the deprotecting reagent is hydrogen chloride in the presence of a solvent, and the solvent is ethyl acetate. In some embodiments, the deprotecting reagent is trifluoroacetic acid. In some embodiments, the deprotecting reagent is phosphoric acid.

[0064] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with a hydrogenation catalyst and hydrogen. In some embodiments, the hydrogenation catalyst is palladium on carbon, palladium hydroxide, rhodium on carbon, rhodium on alumina, platinum oxide, or platinum on carbon. In some embodiments, the hydrogenation catalyst is palladium on carbon. In some embodiments, the hydrogenation catalyst is palladium hydroxide. In some embodiments, the hydrogenation catalyst is rhodium on carbon. In some embodiments, the hydrogenation catalyst is rhodium on alumina. In some embodiments, the hydrogenation catalyst is platinum hydroxide. In some embodiments, the hydrogenation catalyst is platinum on carbon.

[0065] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] and a compound of the following structure: [ka] with a base. In some embodiments, the base is a mixture of aqueous potassium bicarbonate and potassium carbonate. In some embodiments, the base is potassium bicarbonate. In some embodiments, the base is potassium carbonate. In some embodiments, the base is potassium phosphate.

[0066] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with an oxidizing reagent. In some embodiments, the oxidizing reagent is selected from 2,2,6,6-tetramethylpiperidine 1-oxyl, T3P, and trichloroisocyanuric acid (TCCA). In some embodiments, the oxidizing reagent is 2,2,6,6-tetramethylpiperidine 1-oxyl. In some embodiments, the oxidizing reagent is T3P. In some embodiments, the oxidizing reagent is trichloroisocyanuric acid (TCCA).

[0067] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with a base in a solvent. In some embodiments, the base is aqueous sodium hydroxide. In some embodiments, the solvent is selected from tetrahydrofuran, N-methyl-2-pyrrolidone, methanol, isopropanol, and tert-butanol. In some embodiments, the solvent is isopropanol. In some embodiments, the solvent is tetrahydrofuran. In some embodiments, the solvent is N-methyl-2-pyrrolidone. In some embodiments, the solvent is methanol. In some embodiments, the solvent is tert-butanol.

[0068] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with lithium chloride and acetic acid.

[0069] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] and a compound of the following structure: [ka] with a base in the presence of a solvent. In some embodiments, the base is selected from sodium hydride, lithium bis(trimethylsilyl)amide, potassium tert-butoxide, and triethylamine / magnesium chloride. In some embodiments, the base is triethylamine / magnesium chloride. In some embodiments, the base is sodium hydride. In some embodiments, the base is lithium bis(trimethylsilyl)amide. In some embodiments, the base is potassium tert-butoxide. In some embodiments, the solvent is tetrahydrofuran or 2-methyltetrahydrofuran. In some embodiments, the solvent is 2-methyltetrahydrofuran. In some embodiments, the solvent is tetrahydrofuran.

[0070] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with dimethyl malonate, potassium iodide, and a base. In some embodiments, the base is selected from sodium hydride, lithium bis(trimethylsilyl)amide, sodium bis(trimethylsilyl)amide, potassium bis(trimethylsilyl)amide, potassium carbonate, sodium carbonate, and cesium carbonate. In some embodiments, the base is cesium carbonate. In some embodiments, the base is sodium hydride. In some embodiments, the base is lithium bis(trimethylsilyl)amide. In some embodiments, the base is sodium bis(trimethylsilyl)amide. In some embodiments, the base is potassium bis(trimethylsilyl)amide. In some embodiments, the base is potassium carbonate. In some embodiments, the base is sodium carbonate.

[0071] In some embodiments of the method for making methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), a compound having the following structure: [ka] However, a compound having the following structure: [ka] with toluenesulfonyl chloride and a base in the presence of a solvent. In some embodiments, the base is triethylamine. In some embodiments, the solvent is dichloromethane.

[0072] Pharmaceutical Compositions and Methods of Administration Administration of the P2X3 antagonists described herein can be in any pharmaceutical form containing a therapeutically effective amount of the P2X3 antagonist alone or in combination with a pharmaceutically acceptable carrier.

[0073] Pharmaceutical compositions can be formulated in a conventional manner using one or more physiologically acceptable carriers, including excipients and auxiliary agents that facilitate the processing of active compounds into pharmaceutically usable preparations.Suitable formulation depends on the selected route of administration.More details about the excipients suitable for the pharmaceutical compositions described herein can be found in, for example, Remington: The Science and Practice of Pharmacy, Nineteenth Edition (Easton, Pa.: Mack Publishing Company, 1995); Hoover, John E., Remington's Pharmaceutical Sciences, Mack Publishing Co., Easton, Pennsylvania 1975; Liberman, HA and Lachman, L., Eds., Pharmaceutical Dosage Forms, Marcel Decker, New York, NY, 1980; and Pharmaceutical Dosage Forms and Drug Delivery Systems, Seventh Edition (Lippincott Williams & Wilkins1999), the disclosures of which are incorporated herein by reference.

[0074] As used herein, a pharmaceutical composition refers to a mixture of Compound 1 described herein with other chemical components, such as carriers, stabilizers, diluents, dispersants, suspending agents, thickeners, and / or excipients. Pharmaceutical compositions facilitate the administration of a compound to an organism. In practicing the treatment or use methods provided herein, a therapeutically effective amount of a compound described herein is administered in a pharmaceutical composition to a mammal having the disease, disorder, or condition to be treated. In some embodiments, the mammal is a human. The therapeutically effective amount can vary widely depending on the severity of the disease, the age and relative health of the subject, the potency of the compound used, and other factors. Compound 1 can be used alone or in combination with one or more therapeutic agents as components of a mixture (such as in combination therapy).

[0075] The pharmaceutical formulations described herein can be administered to a subject by multiple routes of administration, including, but not limited to, oral, parenteral (e.g., intravenous, subcutaneous, intramuscular), intranasal, buccal, topical, rectal, or transdermal routes of administration. Furthermore, the pharmaceutical compositions described herein, including Compound 1 described herein, can be formulated into any suitable dosage form, including, but not limited to, aqueous oral dispersions, solutions, gels, syrups, elixirs, slurries, suspensions, aerosols, controlled release formulations, fast-dissolve formulations, effervescent formulations, lyophilized formulations, tablets, powders, pills, dragees, capsules, delayed release formulations, sustained release formulations, pulsatile release formulations, multiparticulate formulations, and combinations of immediate release and controlled release formulations.

[0076] In some embodiments, Compound 1 is formulated in a tablet dosage form. In some embodiments, Compound 1 is formulated in a capsule dosage form. In some embodiments, Compound 1 is formulated in a suspension dosage form. In some embodiments, Compound 1 is formulated as a powder-containing capsule dosage form. In some embodiments, Compound 1 is formulated as a powder-containing bottle for reconstitution as a suspension.

[0077] Pharmaceutical compositions containing the compounds described herein may be manufactured in a conventional manner, for example, by way of example only, conventional mixing, dissolving, granulating, dragee-making, filling, emulsifying, encapsulating, entrapping or compressing processes.

[0078] Dosing may be repeated depending on the pharmacokinetic parameters of the formulation and the route of administration used.

[0079] For ease of administration and uniformity of dosage, it is particularly advantageous to prepare composition in dosage unit form.Dose unit form as used herein refers to the physically separate unit that is suitable as a unit dose for the mammalian subject that is treated; each unit contains a predetermined amount of active compound that is calculated to produce desired therapeutic effect in association with required pharmaceutical carrier. The specifications for the dosage unit form are determined by and directly depend on (a) the unique properties of Compound 1 and the specific therapeutic effect to be achieved, and (b) the limitations inherent in the technology of compounding such active compounds for individual treatment sensitivity. A specific dose can be easily calculated by one skilled in the art, for example, based on the patient's approximate body weight or body surface area, or the volume of the body cavity to be occupied. The dose is also calculated depending on the specific route of administration selected. Further refinement of the calculations necessary to determine the appropriate dose for treatment is routinely performed by those skilled in the art. The exact dose is determined in conjunction with standard dose-response studies. It will be understood that the amount of the composition actually administered will be determined by those skilled in the art in light of relevant circumstances, including the state or condition being treated, the selection of the composition to be administered, the age, weight, and response of the individual patient, the severity of the patient's symptoms, and the selected route of administration.

[0080] Administration Methods and Treatment Regimen The compound described herein can be used for the preparation of the medicine for the modulation of P2X3, or for the treatment of the disease or condition that is at least partially benefited from the modulation of P2X3.In addition, the method for treating any of the disease or condition described herein in the subject that needs such treatment comprises administering to said subject the pharmaceutical composition that comprises at least one compound described herein, or its pharmaceutically acceptable salt, or its pharmaceutically acceptable solvate or hydrate in a therapeutically effective amount.

[0081] Compositions containing the compound(s) described herein can be administered for prophylactic and / or therapeutic treatments. In therapeutic applications, compositions are administered to a patient already suffering from a disease or condition in an amount sufficient to cure or at least partially arrest the symptoms of the disease or condition. Amounts effective for this use will depend on the severity and course of the disease or condition, previous treatments, the patient's health status, weight, and response to the drugs, and the judgment of the treating physician.

[0082] In prophylactic applications, compositions containing the compounds described herein are administered to patients susceptible to or otherwise at risk of a particular disease, disorder, or condition. Such an amount is defined as a "prophylactically effective amount or dose." In this use, the precise amount also depends on the patient's health, weight, etc. When used in patients, the amount effective for this use will depend on the severity and course of the disease, disorder, or condition, previous treatments, the patient's health status and response to the drugs, and the judgment of the treating physician.

[0083] If the patient's condition does not improve, at the physician's discretion, the compounds can be administered chronically, i.e., long-term (including throughout the patient's lifetime), to ameliorate or otherwise control or limit the symptoms of the patient's disease or condition.

[0084] If the patient's condition improves, at the physician's discretion, administration of the compound can be continued, or the amount of drug administered can be temporarily reduced or discontinued for a period of time (i.e., a "drug holiday"). The length of a drug holiday can vary from 2 days to 1 year, and examples include 2, 3, 4, 5, 6, 7, 10, 12, 15, 20, 28, 35, 50, 70, 100, 120, 150, 180, 200, 250, 280, 300, 320, 350, 365 days, etc. The dose reduction during the drug holiday may be from about 10% to about 100%, including, by way of example, about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, or about 100%.

[0085] Once the patient's condition has improved, a maintenance dose is administered as needed. Thereafter, depending on the symptoms, the dosage and / or frequency of administration can be reduced to a level at which the improved disease, disorder, or condition is maintained. However, if symptoms recur, long-term intermittent treatment may be required.

[0086] The amount of a given agent corresponding to such an amount will vary depending on factors such as the particular compound, the disease or condition and its severity, the identity (e.g., body weight) of the subject or host requiring treatment, and the like, but can nevertheless be determined in an art-recognized manner depending on the particular circumstances surrounding the case, including, for example, the particular agent being administered, the route of administration, the condition being treated, and the subject or host being treated. In general, however, doses employed in adult human treatment will typically range from about 0.01 mg per day to about 5000 mg per day, and in some embodiments, from about 1 mg per day to about 1500 mg per day. The desired dose can conveniently be presented as a single dose or as divided doses administered simultaneously (or closely spaced), or at appropriate intervals (e.g., two, three, four or more subdoses per day).

[0087] The pharmaceutical compositions described herein may be in unit dosage form suitable for single administration of a precise dose. In dosage form, the formulation is divided into unit doses containing appropriate amounts of one or more compounds. The unit dose may be in the form of a package containing individual amounts of the formulation. Non-limiting examples include packaged tablets or capsules, and powders in vials, capsules, bottles, or ampoules. Aqueous suspension compositions may be packaged in single-dose non-reclosable containers. Alternatively, multi-dose reclosable containers can be used, in which case it is common to include a preservative in the composition. For example, parenteral injection formulations can be presented in unit dosage form (including but not limited to ampoules) or multi-dose containers with added preservatives. [Example]

[0088] All chemicals, reagents and solvents were purchased commercially when available and used without further purification.

[0089] Example 1: Synthesis of methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1) [ka]

[0090] Step 1: To a mixture of (S)-3,5-difluoro-4-(3-(4-(methoxycarbonyl)morpholin-2-yl)propanoyl)benzoic acid in 5 V of THF was added 2 equivalents of CDI at 20-30 °C. The reaction mixture was stirred for 0.5-1 h, then 2.5 equivalents of DIPEA were added dropwise, followed by 2.0 equivalents of MeNH2.HCl in portions. The reaction mixture was stirred at that temperature for 2-4 h and then quenched by the dropwise addition of 2.5 V of HO at 20-30 °C. The resulting mixture was extracted twice with DCM. The combined organic layers were washed twice with 2.5X 20% NH4Cl solution and twice with water. The organic layer was then solvent-exchanged to EtOAc. The mixture was stirred at 45-55 °C for 1-2 h, then at 20-30 °C for 1-2 h. The resulting suspension was further cooled to 0-10°C and stirred at that temperature for 1-2 hours. The mixture was filtered, and the wet cake was slurried in EtOAc. The mixture was filtered, and the wet cake was dried under vacuum at 35-55°C to give the intermediate methyl (S)-2-(3-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-3-oxopropyl)morpholine-4-carboxylate. LCMS (ESI, m / z): 371.1 [M+H] + . 1 H NMR (400 MHz, CDCl3) δ 1.77 - 1.99 (m, 2 H), 2.67 (br s, 1 H), 2.91 - 3.10 (m, 6 H), 3.36 - 3.52 (m, 2 H), 3.72 (s, 3 H), 3.79 - 4.05 (m, 3H), 6.25 (br s, 1 H), 7.31 - 7.40 (m, 2 H).

[0091] Step 2: To a solution of methyl (S)-2-(3-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-3-oxopropyl)morpholine-4-carboxylate in DCM, NBS (1.0 equiv.) was added. The reaction mixture was cooled to -5 to 5 °C, and trifluoromethanesulfonic acid (1.0 equiv.) was added dropwise. The mixture was stirred at 25 to 30 °C. Upon completion of the reaction, 7% aqueous NaHCO3 solution was added at -5 to 5 °C, and ascorbic acid was added to adjust the pH to 5 to 6. The layers were separated, and the aqueous layer was back-extracted twice with DCM. The combined organic layers were washed with water, and the resulting DCM solution of methyl (2S)-2-(2-bromo-3-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-3-oxopropyl)morpholine-4-carboxylate was used directly in the next step. LCMS (ESI, m / z): 449.2 and 451.1 [M+H] + . 1 H NMR (400 MHz, CDCl3) δ 1.57 (br s, 1 H), 2.04 - 2.24 (m, 1 H), 2.25 - 2.40 (m, 1 H), 2.56 (br dd, J=13.51, 10.38 Hz, 1 H), 2.77 (br d,J=3.75 Hz, 1 H), 2.88 - 3.11 (m, 4 H), 3.35 - 3.59 (m, 2 H), 3.61 - 3.78 (m, 4 H), 3.80 - 4.18 (m, 3 H), 5.18 (td, J=10.19, 3.50 Hz, 1 H), 6.08 - 6.65 (m, 1H), 7.38 (br t, J=7.38 Hz, 2 H).

[0092] Step 3: A solution of methyl (2S)-2-(2-bromo-3-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-3-oxopropyl)morpholine-4-carboxylate in DCM was concentrated to dryness and the solvent was switched to ACN. To the resulting solution was added 4-methylpyridin-2-amine (10.0 equiv.), and the reaction mixture was heated to 30 °C and stirred at this temperature for 24 h. The reaction mixture was then heated at 50 °C for 64 h. Upon completion, the reaction mixture was concentrated and the solvent was switched to DCM. Water was added, and the mixture was cooled to 0-10 °C. The pH was adjusted to 4.0-4.5 with H2SO4, and the layers were separated. To the aqueous layer was added DCM, and the pH was adjusted to 3.0-3.5 with H2SO4 at 0-10 °C. The layers were separated. To the aqueous layer was added DCM, and the pH was adjusted to 2.0-2.5 with H2SO4 at 0-10 °C. The layers were separated. The combined organic layers were concentrated and the solvent was switched to THF. The resulting THF solution was charged with 10% aqueous NaOH (1.5 equiv.) and NaBH4 (0.45 equiv.). The mixture was stirred at 20°C for 2-5 h. The reaction mixture was quenched with water at 0-10°C and extracted with MTBE followed by DCM. DCM was added to the aqueous layer, and the pH was adjusted to 5.6-5.8 with 2N HCl at 0-10°C. The layers were separated, and the aqueous layer was extracted three times with DCM. The combined organic layers were concentrated, and the solvent was switched to MeOH. The resulting mixture was stirred at 55-65°C for 0.5 h, then cooled to -5-5°C and stirred at that temperature for 2 h. Water (10 V) was added dropwise, and the mixture was stirred at this temperature for 3 h. The suspension was filtered, and the wet cake was washed with water and then dissolved in MeOH (7 V). The solution was heated to 55-65°C for 1 hour and then cooled to 20-30°C. The mixture was partially concentrated and cooled to -5-5°C. Water was added dropwise at -5-5°C, and the mixture was stirred at this temperature for 1 hour. The suspension was filtered, and the resulting wet cake was washed with water and then dried under vacuum at 55-65°C to give methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1) as a white solid. LCMS (ESI, m / z): 459.3 [M+H] + . 1H NMR (400 MHz, DMSO-d6) δ ppm 2.38 (s, 3 H), 2.82 (d, J=4.27 Hz, 4 H), 2.98 - 3.09 (m, 2 H), 3.22 (td, J=11.67, 2.76 Hz, 1 H), 3.47 (br d, J=3.51 Hz, 1 H), 3.55 (s, 3 H), 3.62 (br d, J=9.29 Hz, 2 H), 3.73 (br d, J=12.30 Hz, 1 H), 6.84 (dd, J=7.03, 1.51 Hz, 1 H), 7.35 (s, 1 H), 7.65 (d, J=8.03 Hz, 2 H), 8.42 (d, J=7.03 Hz, 1 H), 8.69 (br d, J=4.52 Hz, 1 H).

[0093] Example 2: Potency and selectivity for human P2X3 and P2X2 / 3 receptors The ability of Compound 1 described herein to act as an antagonist of P2X3 and P2X2 / P2X3 channels (encoded by the human P2RX2 and P2RX3 genes and stably expressed in HEK293 cells) was evaluated using a Fluo-8 calcium kit. Compound 1 was evaluated at 12 concentrations.

[0094] To evaluate the antagonist effect, cells were preincubated with compound 1 for 20 minutes and then stimulated with the P2X3 and P2X2 / P2X3 agonist α,β-methylene ATP (meATP) at final concentrations of 3 μM and 30 μM. Four minutes and 50 seconds after the addition of meATP, ionomycin was added at a final concentration of 5 μM to obtain the maximum possible calcium influx and fluorescence signal from the cells. Fluorescence was continuously recorded for 10 minutes, starting 10 seconds before the addition of meATP. The IC obtained by the above method was 50 have shown that compound 1 is a selective P2X3 antagonist (P2X3IC 50 =11nM; P2X2 / 3 IC 50 >30 μM).

[0095] The examples and embodiments described herein are for illustrative purposes only, and in some embodiments, various modifications or variations are within the scope of the disclosure and the appended claims.

Claims

1. 1. A process for preparing methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), comprising: A) A compound having the following structure: 【Chemical 1】 and 2,2,6,6-tetramethylpiperidine 1-oxyl or T3P, which has the structure: 【Chemistry 2】 reacting with; B) Then, a compound having the following structure: 【Chemistry 3】 with a mixture of potassium carbonate and potassium bicarbonate or potassium phosphate to produce a compound of the following structure: 【Chemistry 4】 to obtain; C) Then, a compound of the following structure: 【Chemistry 5】 with palladium on carbon and hydrogen to produce a compound of the following structure: 【Chemistry 6】 to obtain; D) Then, a compound of the following structure: 【Chemistry 7】 with hydrogen chloride in ethyl acetate to give a compound of the following structure: 【Chemistry 8】 to obtain; E) Then, a compound of the following structure: 【Chemistry 9】 with methyl chloroformate and aqueous sodium bicarbonate to give a compound of the following structure: 【Chemistry 10】 to obtain; F) Then, a compound of the following structure: 【Chemistry 11】 with carbonyldiimidazole and methylamine or methylamine hydrochloride to give a compound of the following structure: 【Chemistry 12】 to obtain; G) Then, a compound of the following structure: 【Chemistry 13】 with N-bromosuccinimide and trifluoromethanesulfonic acid to give a compound of the following structure: 【Chemistry 14】 to obtain; H) Then, a compound of the following structure: 【Chemistry 15】 with 4-methylpyridin-2-amine to produce a compound of the following structure: 【Chemistry 16】 to obtain; A method comprising:

2. 1. A process for preparing methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), comprising: A) A compound of the following structure: 【Chemistry 17】 with toluenesulfonyl chloride and triethylamine to give a compound of the following structure: 【Chemistry 18】 to obtain; B) Then, a compound of the following structure: 【Chemistry 19】 with dimethyl malonate, potassium iodide and cesium carbonate to give a compound of the following structure: 【Chemistry 20】 to obtain; C) Then, a compound of the following structure: 【Chemical Formula 21】 with triethylamine / magnesium chloride to give a compound of the following structure: 【Chemical 22】 to obtain; D) Then, a compound of the following structure: 【Chemical 23】 with lithium chloride and acetic acid to produce a compound of the following structure: 【Chemistry 24】 to obtain; E) Then, a compound of the following structure: 【Chemistry 25】 with aqueous sodium hydroxide to produce a compound of the following structure: 【Chemical 26】 to obtain; F) Then, a compound of the following structure: 【Chemical 27】 with hydrogen chloride in ethyl acetate to give a compound of the following structure: 【Chemical 28】 to obtain; G) Then, a compound of the following structure: 【Chemical 29】 with methyl chloroformate and aqueous sodium bicarbonate to give a compound of the following structure: 【Chemistry 30】 to obtain; H) Then, a compound of the following structure: 【Chemical 31】 with carbonyldiimidazole and methylamine or methylamine hydrochloride to give a compound of the following structure: 【Chemical 32】 to obtain; I) Then, a compound of the following structure: 【Chemical 33】 with N-bromosuccinimide and trifluoromethanesulfonic acid to give a compound of the following structure: 【Chemical 34】 to obtain; J) Then, a compound of the following structure: 【Chemistry 35】 with 4-methylpyridin-2-amine to produce a compound of the following structure: 【Chemical 36】 to obtain; A method comprising:

3. Methyl (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1): 【Chemical 37】 1. A method for preparing a compound of the following structure: 【Chemical 38】 contacting 4-methylpyridin-2-amine with a compound of formula (I) in the presence of a solvent; A method comprising:

4. 4. The method of claim 3, wherein the solvent is acetonitrile or acetonitrile-containing water.

5. A compound of the following structure: 【Chemical Formula 39】 is a compound of the following structure: 【Chemistry 40】 The method according to claim 3 or 4, wherein the compound is produced by a method comprising contacting a compound of formula (I) with a brominating reagent.

6. The method of claim 5, wherein the brominating reagent is N-bromosuccinimide in the presence of an acid.

7. 7. The method of claim 6, wherein the acid is trifluoromethanesulfonic acid.

8. A compound of the following structure: 【Chemistry 41】 is a compound of the following structure: 【Chemistry 42】 8. The method of any one of claims 3 to 7, wherein the compound is produced by a process comprising contacting the compound with an amide coupling reagent and methylamine or a salt of methylamine.

9. 9. The method of claim 8, wherein the amide coupling reagent is carbonyldiimidazole.

10. 9. The method of claim 8, wherein the amide coupling reagent is propanephosphonic anhydride (T3P).

11. A compound of the following structure: 【Chemistry 43】 is a compound of the following structure: 【Chemical 44】 5. The method of claim 3 or 4, wherein the compound is prepared by a process comprising contacting the compound with an amide coupling reagent and methylamine or a salt of methylamine.

12. 12. The method of claim 11, wherein the amide coupling reagent is carbonyldiimidazole.

13. 12. The method of claim 11, wherein the amide coupling reagent is propanephosphonic anhydride (T3P).

14. A compound of the following structure: 【Chemistry 45】 is a compound of the following structure: 【Chemistry 46】 The method according to any one of claims 11 to 13, wherein the compound is produced by a method comprising contacting a compound of formula (I) with a brominating reagent.

15. 15. The method of claim 14, wherein the brominating reagent is N-bromosuccinimide in the presence of an acid.

16. 16. The method of claim 15, wherein the acid is trifluoromethanesulfonic acid.

17. A compound of the following structure: 【Chemistry 47】 is a compound of the following structure: 【Chemistry 48】 17. The method of any one of claims 3 to 16, wherein the compound is produced by a process comprising contacting the compound with methyl chloroformate and a base.

18. 18. The method of claim 17, wherein the base is aqueous sodium bicarbonate.

19. A compound of the following structure: 【Chemistry 49】 is a compound of the following structure: 【Chemistry 50】 with a deprotecting reagent selected from 1) hydrogen chloride in the presence of a solvent, 2) trifluoroacetic acid, and 3) phosphoric acid.

20. 20. The method of claim 19, wherein the deprotecting reagent is hydrogen chloride in the presence of a solvent, and the solvent is ethyl acetate.

21. A compound of the following structure: 【Chemistry 51】 is a compound of the following structure: 【Chemistry 52】 The method according to any one of claims 3 to 20, wherein the olefin is produced by a process comprising contacting the olefin with a hydrogenation catalyst and hydrogen.

22. 22. The method of claim 21, wherein the hydrogenation catalyst is palladium on carbon, palladium hydroxide, rhodium on carbon, rhodium on alumina, platinum oxide, or platinum on carbon.

23. 23. The method of claim 22, wherein the hydrogenation catalyst is palladium on carbon.

24. A compound of the following structure: 【Chemistry 53】 is a compound of the following structure: 【Chemical Formula 54】 and a compound of the structure: 【Chemistry 55】 The method according to any one of claims 3 to 23, wherein the compound is produced by a process comprising contacting a compound of formula (I) with a base.

25. 25. The method of claim 24, wherein the base is a mixture of aqueous potassium bicarbonate and potassium carbonate, or the base is potassium phosphate.

26. A compound of the following structure: 【Chemical Formula 56】 is a compound of the following structure: 【Chemical 57】 The method according to any one of claims 3 to 25, wherein the compound is produced by a process comprising contacting a compound of formula (I) with an oxidation reagent.

27. 27. The method of claim 26, wherein the oxidation reagent is selected from 2,2,6,6-tetramethylpiperidine 1-oxyl, T3P, and trichloroisocyanuric acid (TCCA).

28. A compound of the following structure: 【Chemistry 58】 is a compound of the following structure: 【Chemical 59】 The method of any one of claims 3 to 20, wherein the compound is produced by a process comprising contacting a base in a solvent with the compound.

29. 29. The method of claim 28, wherein the base is aqueous sodium hydroxide.

30. 30. The method of claim 28 or 29, wherein the solvent is selected from tetrahydrofuran, N-methyl-2-pyrrolidone, methanol, isopropanol and tert-butanol.

31. The method of any one of claims 28 to 30, wherein the solvent is isopropanol.

32. A compound of the following structure: 【Chemistry 60】 is a compound of the following structure: 【Hua 61】 32. The method of any one of claims 28 to 31, wherein the hydroxybenzoate is produced by a process comprising contacting a hydroxybenzoate with lithium chloride and acetic acid.

33. A compound of the following structure: 【Hua 62】 is a compound of the following structure: 【Chemistry 63】 and a compound of the structure: 【Hua 64】 The method according to any one of claims 28 to 32, wherein the compound is produced by a process comprising contacting a base with a compound of formula (I) in the presence of a solvent.

34. 34. The method of claim 33, wherein the base is selected from sodium hydride, lithium bis(trimethylsilyl)amide, potassium tert-butoxide, and triethylamine / magnesium chloride.

35. 35. The method of claim 33 or 34, wherein the base is triethylamine / magnesium chloride.

36. The method of any one of claims 33 to 35, wherein the solvent is tetrahydrofuran or 2-methyltetrahydrofuran.

37. 37. The method of any one of claims 33 to 36, wherein the solvent is 2-methyltetrahydrofuran.

38. A compound of the following structure: 【Chemistry 65】 is a compound of the following structure: 【Hua 66】 38. The method of any one of claims 33 to 37, wherein the compound is produced by a process comprising contacting a compound selected from the group consisting of dimethyl malonate, potassium iodide and a base.

39. 39. The method of claim 38, wherein the base is selected from sodium hydride, lithium bis(trimethylsilyl)amide, sodium bis(trimethylsilyl)amide, potassium bis(trimethylsilyl)amide, potassium carbonate, sodium carbonate, and cesium carbonate.

40. 40. The method of claim 39, wherein the base is cesium carbonate.

41. A compound of the following structure: 【Hua 67】 is a compound of the following structure: 【Chemistry 68】 41. The method of any one of claims 33 to 40, wherein the compound is produced by a process comprising contacting the compound with toluenesulfonyl chloride and a base in the presence of a solvent.

42. 42. The method of claim 41, wherein the base is triethylamine.

43. 43. The method of claim 31 or 42, wherein the solvent is dichloromethane.

44. A compound having the following structure: 【Chemical Formula 69】 or a pharmaceutically acceptable salt thereof or a cocrystal thereof.

45. A compound having the following structure: 【Chemistry 70】 or a pharmaceutically acceptable salt thereof or a cocrystal thereof.

46. A compound having the following structure: 【Chemical 71】 or a pharmaceutically acceptable salt thereof.

Images