Preparation of p2x3 antagonists

Abstract

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

Description

Background Art

[0001] P2X purinergic receptors are a family of ion channels activated by extracellular adenosine triphosphate (ATP). Purinergic receptors are associated with 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 method for synthesizing a P2X3 antagonist, wherein the P2X3 antagonist is (S)-methyl 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 cocrystal thereof. The various intermediates mentioned herein can be prepared according to the methods disclosed in WO 2021 / 161109 and WO 2023 / 021328.

[0003] One aspect described herein is a method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), comprising:

[0004] A) A compound having the following structure:

[0005] Reaction with 2,2,6,6-tetramethylpiperidinyl 1-oxyl or T3P generates compounds with the following structure:

[0006]

[0007] B) Then a compound having the following structure:

[0008] Reacts with a mixture of potassium carbonate and potassium bicarbonate or potassium phosphate to produce a compound with the following structure:

[0009]

[0010] C) Then a compound having the following structure:

[0011] Reaction with palladium on carbon and hydrogen produces a compound with the following structure:

[0012]

[0013] D) Then a compound having the following structure:

[0014] Reaction with hydrogen chloride in ethyl acetate produces a compound with the following structure:

[0015]

[0016] E) Then a compound having the following structure:

[0017] It reacts with methyl chloroformate and aqueous sodium bicarbonate to produce a compound with the following structure:

[0018]

[0019] F) Then a compound having the following structure:

[0020] It reacts with carbonyldiimidazole and methylamine or methylamine hydrochloride to generate a compound with the following structure:

[0021]

[0022] G) Then a compound having the following structure:

[0023] Reaction with N-bromosuccinimide and trifluoromethanesulfonic acid produces a compound with the following structure:

[0024]

[0025] H) Then a compound having the following structure:

[0026] Reaction with 4-methylpyridin-2-amine generates a compound with the following structure:

[0027]

[0028] Another aspect described herein is a method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), comprising:

[0029] A) A compound having the following structure:

[0030] Reaction with tosyl chloride and triethylamine produces a compound with the following structure:

[0031]

[0032] B) Then a compound having the following structure:

[0033] Reaction with dimethyl malonate, potassium iodide and cesium carbonate produces a compound with the following structure:

[0034]

[0035] C) Then a compound having the following structure:

[0036] Reaction with triethylamine / magnesium chloride produces a compound with the following structure:

[0037]

[0038] D) Then a compound having the following structure:

[0039] It reacts with lithium chloride and acetic acid to produce a compound with the following structure:

[0040]

[0041] E) Then a compound having the following structure:

[0042] It reacts with aqueous sodium hydroxide to produce a compound with the following structure:

[0043]

[0044] F) Then a compound having the following structure:

[0045] Reaction with hydrogen chloride in ethyl acetate generates a compound with the following structure:

[0046]

[0047] G) Then a compound having the following structure:

[0048] It reacts with methyl chloroformate and aqueous sodium bicarbonate to produce a compound with the following structure:

[0049]

[0050] H) Then a compound having the following structure:

[0051] It reacts with carbonyldiimidazole and methylamine or methylamine hydrochloride to generate a compound with the following structure:

[0052]

[0053] I) then a compound having the following structure:

[0054] Reaction with N-bromosuccinimide and trifluoromethanesulfonic acid produces a compound with the following structure:

[0055]

[0056] J) Then the compound having the following structure:

[0057] Reaction with 4-methylpyridin-2-amine generates a compound with the following structure:

[0058]

[0059] Another aspect described herein is a method of preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1):

[0060]

[0061] It includes reacting a compound having the following structure in the presence of a solvent:

[0062] and contacting with 4-methylpyridin-2-amine. In some embodiments, the solvent is selected from acetonitrile and aqueous acetonitrile.

[0063] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0064] is by including a compound having the following structure:

[0065] In some embodiments, the brominating agent is N-bromosuccinimide. In some embodiments, the brominating agent is CuBr2. In some embodiments, the brominating agent is N-bromosuccinimide in the presence of an acid. In some embodiments, the acid is trifluoromethanesulfonic acid. In some embodiments, (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylic acid methyl ester (Compound 1) is prepared with the following structure:

[0066] is by including a compound having the following structure:

[0067] In some embodiments, the solvent is DCM.

[0068] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0069] is by including a compound having the following structure:

[0070] The method of contacting an amide coupling reagent with methylamine or a methylamine salt. In some embodiments, the amide coupling reagent is carbonyl diimidazole. In some embodiments, the amide coupling reagent is propanephosphonic anhydride (T3P).

[0071] In some embodiments, (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1) is prepared, a compound having the following structure:

[0072] is by including a compound having the following structure:

[0073] The invention relates to a method of contacting an amide coupling reagent and methylamine or a methylamine salt 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).

[0074] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0075] is by including a compound having the following structure:

[0076] The method of contacting an amide coupling reagent with methylamine or a methylamine salt. In some embodiments, the amide coupling reagent is carbonyl diimidazole. In some embodiments, the amide coupling reagent is propanephosphonic anhydride (T3P).

[0077] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0078] is by including a compound having the following structure:

[0079] In some embodiments, the brominating agent is N-bromosuccinimide. In some embodiments, the brominating agent is CuBr2. In some embodiments, the brominating agent is N-bromosuccinimide in the presence of an acid. In some embodiments, the acid is trifluoromethanesulfonic acid.

[0080] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0081] is by including a compound having the following structure:

[0082] The method is prepared by contacting methyl chloroformate with a base. In some embodiments, the base is an aqueous sodium bicarbonate solution.

[0083] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0084] is by including a compound having the following structure:

[0085] The method of contacting with a deprotecting agent selected from the group consisting of: 1) hydrogen chloride in the presence of a solvent, 2) trifluoroacetic acid, and 3) phosphoric acid. In some embodiments, the deprotecting agent is hydrogen chloride in the presence of a solvent, and the solvent is ethyl acetate. In some embodiments, the deprotecting agent is trifluoroacetic acid. In some embodiments, the deprotecting agent is phosphoric acid.

[0086] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0087] is by including a compound having the following structure:

[0088] 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.

[0089] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0090] is by including a compound having the following structure:

[0091] With a compound having the following structure:

[0092] In some embodiments, the base is a mixture of an aqueous potassium bicarbonate solution and potassium carbonate. In some embodiments, the base is potassium phosphate.

[0093] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0094] is by including a compound having the following structure:

[0095] In some embodiments, the oxidant is selected from 2,2,6,6-tetramethylpiperidinyl 1-oxyl, T3P and trichloroisocyanuric acid (TCCA). In some embodiments, the oxidant is 2,2,6,6-tetramethylpiperidinyl 1-oxyl. In some embodiments, the oxidant is T3P. In some embodiments, the oxidant is trichloroisocyanuric acid (TCCA).

[0096] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0097] is by including a compound having the following structure:

[0098] In some embodiments, the alkali is aqueous sodium hydroxide. In some embodiments, the solvent is selected from tetrahydrofuran, N-methyl-2-pyrrolidone, methanol, isopropanol and tert-butyl alcohol. In some embodiments, the solvent is isopropanol.

[0099] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0100] is by including a compound having the following structure:

[0101] Prepared by contacting with lithium chloride and acetic acid.

[0102] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0103] is by including a compound having the following structure:

[0104] With a compound having the following structure:

[0105] and 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.

[0106] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0107] is by including a compound having the following structure:

[0108] The method of contacting 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.

[0109] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0110] is by including a compound having the following structure:

[0111] In some embodiments, the base is triethylamine. In some embodiments, the solvent is dichloromethane.

[0112] Further disclosed herein are compounds having the following structure:

[0113] or a pharmaceutically acceptable salt or co-crystal thereof.

[0114] Further disclosed herein are compounds having the following structure:

[0115] or a pharmaceutically acceptable salt or co-crystal thereof.

[0116] Further disclosed herein are compounds having the following structure:

[0117] or a pharmaceutically acceptable salt thereof.

[0118] Incorporated by Reference

[0119] 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. DETAILED DESCRIPTION OF THE INVENTION

[0121] Good manufacturing practices are often required for large-scale production of clinically useful drug candidates. Provided herein are certain processes and methods for producing the P2X3 antagonist (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylic acid methyl ester (Compound 1) or a pharmaceutically acceptable salt or cocrystal thereof.

[0122] definition

[0123] As used in the specification and the appended claims, unless otherwise indicated, the following terms have the meanings indicated below.

[0124] As used herein and in the appended claims, the singular forms "a," "an," "and," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "an agent" includes a plurality of such agents and reference to "the cell" includes reference to one or more cells (or a plurality of cells) and equivalents thereof.

[0125] When ranges are used herein for physical properties (eg, molecular weight) or chemical properties (eg, chemical formula), all combinations and subcombinations of ranges and specific embodiments therein are intended to be included.

[0126] When referring to a number or a numerical range, the term "about" means that the referenced number or numerical range is an approximation within the experimental variability (or within statistical experimental error), such that the number or numerical range varies between 1% and 15% of the described number or numerical range.

[0127] The term "comprising" (and related terms such as "including" or "having" or "including") is not intended to exclude those in certain other embodiments, such as embodiments of any composition of matter, composition, method or process, etc. described herein, "consisting of" or "consisting essentially of" the described features.

[0128] The term "subject" or "patient" encompasses mammals and non-mammals. Examples of mammals include, but are not limited to, any member of the class Mammalia: humans, non-human primates such as chimpanzees, and other apes and monkeys; farm animals such as cattle, horses, sheep, goats, pigs; livestock 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, etc. In one embodiment of the methods and compositions provided herein, the mammal is a human.

[0129] As used herein, "treatment" or "treating" or "alleviate" or "improve" are used interchangeably herein. These terms refer to methods of obtaining beneficial or desired results, including but not limited to therapeutic benefit and / or preventive benefit. "Therapeutic benefit" refers to the eradication or improvement of the underlying disorder being treated. Moreover, therapeutic benefit is achieved by eradication or improvement of one or more physiological symptoms associated with the underlying disorder, such that an improvement is observed in the patient, even though the patient still suffers from the underlying disorder. For preventive benefit, the composition is administered to a patient at risk of developing a particular disease, or to a patient reporting one or more physiological symptoms of a disease, even if a diagnosis of the disease has been made.

[0130] "Pharmaceutically acceptable salts" include acid addition salts and base addition salts. Pharmaceutically acceptable salts of any of the compounds described herein are intended to encompass any and all pharmaceutically suitable salt forms. Preferred pharmaceutically acceptable salts of the compounds described herein are pharmaceutically acceptable acid addition salts and pharmaceutically acceptable base addition salts.

[0131] "Pharmaceutically acceptable acid addition salts" refers to those salts which retain the biological effectiveness and properties of the free bases, which are not biologically or otherwise undesirable, and which are formed with inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, hydroiodic acid, hydrofluoric acid, phosphorous acid, and the like. 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, and the like, and including, for example, 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 sulfates, pyrosulfates, bisulfates, sulfites, bisulfites, nitrates, phosphates, monohydrogenphosphates, dihydrogenphosphates, metaphosphates, pyrophosphates, chlorides, bromides, iodides, acetates, trifluoroacetates, propionates, octanoates, isobutyrates, oxalates, malonates, succinates, suberates, sebacates, fumarates, maleates, mandelates, benzoates, chlorobenzoates, methylbenzoates, dinitrobenzoates, phthalates, benzenesulfonates, toluenesulfonates, phenylacetates, citrates, lactates, malates, tartrates, methanesulfonates, etc. Also contemplated are salts of amino acids, such as arginates, gluconates, and galacturonates (see, e.g., Berge S. M. et al., "Pharmaceutical Salts," Journal of Pharmaceutical Science, 66: 1-19 (1997)). The 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.

[0132] "Pharmaceutically acceptable base addition salts" refer to those salts which retain the biological effectiveness and properties of the free acids, which are not biologically or otherwise undesirable. These salts are prepared by the addition of inorganic or organic bases to the free acids. In some embodiments, pharmaceutically acceptable base addition salts are formed with metals or amines such as alkali metals and alkaline earth metals or organic amines. Salts derived from inorganic bases include, but are not limited to, sodium salts, potassium salts, lithium salts, ammonium salts, calcium salts, magnesium salts, iron salts, zinc salts, copper salts, manganese salts, aluminum salts, and the like. 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, and basic ion exchange resins, such as isopropylamine, trimethylamine, diethylamine, triethylamine, tripropylamine, ethanolamine, diethanolamine, 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.

[0133] The term "pharmaceutical combination" as used herein refers to a product produced by mixing or combining more than one active ingredient, and includes fixed and non-fixed combinations of active ingredients. The term "fixed combination" means that the active ingredients are all administered to the patient simultaneously in the form of a single entity or dosage. The term "non-fixed combination" refers to the administration of the active ingredients to the patient as separate entities simultaneously, in parallel or sequentially, without specific time interval restrictions, wherein such administration provides effective levels of the two compounds in the patient's body. The latter also applies to cocktail therapy, for example, the administration of three or more active ingredients.

[0134] As used herein, the terms "co-administered," "co-administered," and the like are intended to encompass 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.

[0135] The term "activator" as used in this specification refers to any molecular species that results in activation of a given receptor, whether or not the species itself binds to the receptor when the species is topically administered or whether or not a metabolite of the species binds to the receptor. Thus, an activator may be a ligand for a receptor or it may be an activator that is metabolized to a ligand for a receptor, i.e., a metabolite that is formed in the tissue and is the actual ligand.

[0136] As used herein, the term "antagonist" refers to a small molecule agent that binds to a nuclear hormone receptor and subsequently reduces agonist-induced nuclear hormone receptor transcriptional activity.

[0137] 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.

[0138] As used herein, the term "inverse agonist" refers to a small molecule agent that binds to a nuclear hormone receptor and subsequently reduces the basal level of nuclear hormone receptor transcriptional activity present in the absence of a known agonist.

[0139] As used herein, the term "modulate" means to interact directly or indirectly with a target protein to change the activity of the target protein, including, by way of example only, to inhibit the activity of the target, or to limit or reduce the activity of the target.

[0140] 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 certain 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 that 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.

[0141] Compound

[0142] In some embodiments, the P2X3 antagonist described herein is (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylic acid methyl ester (Compound 1) or a pharmaceutically acceptable salt or cocrystal thereof. Compound 1 has the following structure:

[0143]

[0144] In some embodiments, the intermediate in the synthesis of compound 1 is In some embodiments, the intermediate in the synthesis of compound 1 is In some embodiments, the intermediate in the synthesis of compound 1 is

[0145] Other forms of compounds

[0146] The compounds described herein may exist as diastereomers, enantiomers or other stereoisomeric forms in some cases. The compounds proposed herein include all diastereomers, enantiomers and epimeric forms and suitable mixtures thereof. The separation of stereoisomers can be carried out by chromatography or by forming diastereomers and separating by recrystallization or chromatography or any combination thereof. (Jean Jacques, Andre Collet, Samuel H. Wilen, "Enantiomers, Racemates and Resolutions", John Wiley And Sons, Inc., 1981, which is incorporated herein by reference for use in the present disclosure). Stereoisomers can also be obtained by stereoselective synthesis.

[0147] In certain cases, compounds may exist as tautomers. All tautomers are included within the formulae described herein.

[0148] Pharmaceutically acceptable salts

[0149] In some embodiments, the compounds described herein exist 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.

[0150] In some embodiments, the compounds described herein have acidic or basic groups and therefore react with any of a variety 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 a suitable acid or base and isolating the salt thus formed.

[0151] In some embodiments, the pharmaceutically acceptable salt of Compound 1 is acetate, benzoate, benzenesulfonate, bitartrate, carbonate, citrate, fumarate, gluconate, hydrobromide, hydrochloride, maleate, methanesulfonate, nitrate, phosphate, salicylate, succinate, sulfate or tartrate. In some embodiments, the pharmaceutically acceptable salt of Compound 1 is monohydrochloride. In further embodiments, the pharmaceutically acceptable salt of Compound 1 is monohydrochloride.

[0152] Solvate

[0153] 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.

[0154] Solvates contain a stoichiometric or non-stoichiometric amount of solvent, and in some embodiments, are formed during the process of crystallization with a pharmaceutically acceptable solvent such as water, ethanol, etc. Hydrates are formed when the solvent is water, or alcoholates are formed when the solvent is alcohol. Solvates of compounds described herein can be conveniently prepared or formed during the process described herein. For example only, hydrates of compounds described herein can be conveniently prepared by recrystallization from a water / organic solvent mixture using an organic solvent (including but not limited to dioxane, tetrahydrofuran or methanol). In addition, compounds provided herein exist in non-solvated forms and solvated forms. In general, for the purposes of compounds and methods provided herein, solvated forms are considered to be equivalent to non-solvated forms.

[0155] Labeled compounds

[0156] In some embodiments, the compounds described herein exist in their isotopically labeled form. In some embodiments, the methods disclosed herein include methods of treating diseases by administering such isotopically labeled compounds. In some embodiments, the methods disclosed herein include methods of treating diseases by administering such isotopically labeled compounds as pharmaceutical compositions. Therefore, in some embodiments, the compounds disclosed herein include isotopically labeled compounds that are identical to those described herein, but in fact one or more atoms are replaced by atoms having an atomic mass or mass number different from the atomic mass or mass number usually found in nature. Examples of isotopes incorporated into the compounds of the present invention include isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur, fluorine and chlorine, for example, respectively. 2 H. 3 H. 13 C. 14 C. 15 N. 18 O. 17 O. 31 P. 32 P. 35 S. 18 F and 36 Cl. Compounds described herein containing the above-mentioned isotopes and / or other isotopes of other atoms and pharmaceutically acceptable salts, esters, solvates, hydrates or derivatives thereof are within the scope of the present invention. Certain isotopically labeled compounds, such as those incorporating radioactive isotopes (e.g. 3 H and 14C) can be used in drug and / or substrate tissue distribution assays. 3 H) and carbon 14 (i.e. 14 C) isotopes are particularly preferred because of their ease of preparation and detectability. In addition, heavy isotopes such as deuterium (i.e. 2 H) substitutions produce certain therapeutic benefits due to greater metabolic stability, such as increased in vivo half-life or reduced dosage requirements. Compared to compound 1 with naturally occurring deuterium levels, the increased deuterium incorporation levels produce a detectable kinetic isotope effect (KIE), which can affect the pharmacokinetic, pharmacological and / or toxicological parameters of compound 1. In some embodiments, the isotopically labeled compound or a pharmaceutically acceptable salt thereof is prepared by any suitable method.

[0157] In some embodiments, at least one hydrogen in Compound 1 is replaced with deuterium.

[0158] 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.

[0159] Preparation process

[0160] In some embodiments, the synthesis of the compounds described herein is accomplished using methods described in the chemical literature, using methods described herein, or by a combination thereof. Additionally, solvents, temperatures, and other reaction conditions set forth herein may vary.

[0161] In other embodiments, starting materials and reagents used to synthesize compounds described herein are synthesized or obtained from commercial sources such as, but not limited to, Sigma-Aldrich, Fischer Scientific (Fischer Chemicals), and Acros Organics.

[0162] In further embodiments, the compounds described herein and other related compounds having different substituents are synthesized using the techniques and materials described herein as well as those recognized in the art, such as 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), March, Advanced Organic Chemistry 4 th Ed., (Wiley 1992); Carey and Sundberg, Advanced Organic Chemistry 4 th Ed.,Vols.A and B(Plenum 2000,2001),and Greenand Wuts,Protective Groups in Organic Synthesis 3 rd Ed., (Wiley 1999) (all of these disclosures are incorporated by reference). General methods for preparing the compounds disclosed herein can be derived from the reactions and the reactions can be modified by using appropriate reagents and conditions to introduce the various moieties found in the formulae provided herein.

[0163] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1):

[0164]

[0165] It includes reacting a compound having the following structure in the presence of a solvent:

[0166] and contacting with 4-methylpyridin-2-amine. In some embodiments, the solvent is selected from acetonitrile and aqueous acetonitrile. In some embodiments, the solvent is acetonitrile. In some embodiments, the solvent is aqueous acetonitrile.

[0167] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0168] is by including a compound having the following structure:

[0169] In some embodiments, the brominating agent is N-bromosuccinimide in the presence of an acid. In some embodiments, the acid is trifluoromethanesulfonic acid. In some embodiments, the brominating agent is copper (II) bromide.

[0170] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0171] is by including a compound having the following structure:

[0172] The method of contacting an amide coupling reagent with methylamine or a methylamine salt. In some embodiments, the amide coupling reagent is carbonyl diimidazole. In some embodiments, the amide coupling reagent is propanephosphonic anhydride (T3P).

[0173] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0174] is by including a compound having the following structure:

[0175] The method of contacting an amide coupling reagent with methylamine or a methylamine salt. In some embodiments, the amide coupling reagent is carbonyl diimidazole. In some embodiments, the amide coupling reagent is propanephosphonic anhydride (T3P).

[0176] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0177] is by including a compound having the following structure:

[0178] In some embodiments, the brominating agent is N-bromosuccinimide in the presence of an acid. In some embodiments, the acid is trifluoromethanesulfonic acid. In some embodiments, the brominating agent is copper (II) bromide. In some embodiments, the brominating agent is liquid bromine.

[0179] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0180] is by including a compound having the following structure:

[0181] The method is prepared by contacting methyl chloroformate with a base. In some embodiments, the base is an aqueous sodium bicarbonate solution.

[0182] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0183] is by including a compound having the following structure:

[0184] The method of contacting with a deprotecting agent selected from the group consisting of: 1) hydrogen chloride in the presence of a solvent, 2) trifluoroacetic acid, and 3) phosphoric acid. In some embodiments, the deprotecting agent is hydrogen chloride in the presence of a solvent, and the solvent is ethyl acetate. In some embodiments, the deprotecting agent is trifluoroacetic acid. In some embodiments, the deprotecting agent is phosphoric acid.

[0185] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0186] is by including a compound having the following structure:

[0187] Prepared by a method of contacting 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 oxide. In some embodiments, the hydrogenation catalyst is platinum on carbon.

[0188] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0189] is by including a compound having the following structure:

[0190] With a compound having the following structure:

[0191] In some embodiments, the base is a mixture of potassium bicarbonate aqueous solution 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.

[0192] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0193] is by including a compound having the following structure:

[0194] In some embodiments, the oxidant is selected from 2,2,6,6-tetramethylpiperidinyl 1-oxyl, T3P and trichloroisocyanuric acid (TCCA). In some embodiments, the oxidant is 2,2,6,6-tetramethylpiperidinyl 1-oxyl. In some embodiments, the oxidant is T3P. In some embodiments, the oxidant is trichloroisocyanuric acid (TCCA).

[0195] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0196] is by including a compound having the following structure:

[0197] In some embodiments, the alkali is aqueous sodium hydroxide solution. In some embodiments, the solvent is selected from tetrahydrofuran, N-methyl-2-pyrrolidone, methanol, isopropanol and tert-butyl alcohol. 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-butyl alcohol.

[0198] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0199] is by including a compound having the following structure:

[0200] Prepared by contacting with lithium chloride and acetic acid.

[0201] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0202] is by including a compound having the following structure:

[0203] With a compound having the following structure:

[0204] and a base in the presence of a solvent. In some embodiments, the base is selected from sodium hydride, bis (trimethylsilyl) lithium 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 bis (trimethylsilyl) lithium 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.

[0205] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0206] is by including a compound having the following structure:

[0207] Prepared by a method of contacting with dimethyl malonate, potassium iodide and a base. In some embodiments, the base is selected from sodium hydride, bis(trimethylsilyl) lithium amide, bis(trimethylsilyl) sodium amide, bis(trimethylsilyl) potassium 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 bis(trimethylsilyl) lithium amide. In some embodiments, the base is bis(trimethylsilyl) sodium amide. In some embodiments, the base is bis(trimethylsilyl) potassium amide. In some embodiments, the base is potassium carbonate. In some embodiments, the base is sodium carbonate.

[0208] In some embodiments of the method for preparing (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1), the compound having the following structure:

[0209] is by including a compound having the following structure:

[0210] In some embodiments, the base is triethylamine. In some embodiments, the solvent is dichloromethane.

[0211] Pharmaceutical compositions and methods of administration

[0212] Administration of the P2X3 antagonists described herein can be in any pharmacological form, including a therapeutically effective amount of the P2X3 antagonist alone or in combination with a pharmaceutically acceptable carrier.

[0213] Pharmaceutical compositions can be formulated in a conventional manner using one or more physiologically acceptable carriers (including excipients and adjuvants) that facilitate processing of the active compound into a pharmaceutically acceptable preparation. The appropriate formulation depends on the route of administration selected. Additional details about suitable excipients for pharmaceutical compositions described herein can be found in, for example, Remington: The Science and Practice of Pharmacy, Nineteenth Ed (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 Ed. (Lippincott Williams & Wilkins 1999), and such disclosures are incorporated herein by reference.

[0214] The pharmaceutical composition used herein refers to a mixture of compound 1 described herein and other chemical components (e.g., carriers, stabilizers, diluents, dispersants, suspending agents, thickeners and / or excipients). The pharmaceutical composition facilitates the administration of the compound to an organism. In the implementation of the treatment or use methods provided herein, a therapeutically effective amount of the compound described herein is administered as a pharmaceutical composition to a mammal suffering from a 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 efficacy of the compound used, and other factors. Compound 1 can be used alone or in combination with one or more therapeutic agents as a component of a mixture (e.g., in combination therapy).

[0215] The pharmaceutical formulations described herein can be administered to a subject by a variety of routes of administration, including but not limited to oral, parenteral (e.g., intravenous, subcutaneous, intramuscular), intranasal, buccal, topical, rectal or transdermal administration. In addition, the pharmaceutical compositions described herein comprising Compound 1 described herein can be formulated into any suitable dosage form, including but not limited to aqueous oral dispersions, liquids, gels, syrups, elixirs, slurries, suspensions, aerosols, controlled release formulations, fast melt formulations, effervescent formulations, lyophilized formulations, tablets, powders, pills, dragees, capsules, delayed release formulations, extended release formulations, pulsed release formulations, multi-particulate formulations, and mixed immediate release and controlled release formulations.

[0216] In some embodiments, Compound 1 is formulated as a tablet dosage form. In some embodiments, Compound 1 is formulated as a capsule dosage form. In some embodiments, Compound 1 is formulated as a suspension dosage form. In some embodiments, Compound 1 is formulated as a powder in a capsule dosage form. In some embodiments, Compound 1 is formulated as a powder in a bottle for reconstitution as a suspension.

[0217] Pharmaceutical compositions comprising the compounds described herein may be manufactured in a conventional manner, such as, by way of example only, by means of conventional mixing, dissolving, granulating, dragee-making, levigating, emulsifying, encapsulating, entrapping or compression processes.

[0218] Depending on the pharmacokinetic parameters of the dosage formulation and the route of administration used, the dosage administration may be repeated.

[0219] For ease of administration and uniformity of dosage, it is particularly advantageous to formulate the composition in dosage unit form. The dosage unit form used herein refers to a physically discrete unit suitable as a single dose for a mammalian subject to be treated; each unit contains a predetermined amount of active compound, which is calculated to produce the desired therapeutic effect in association with the desired pharmaceutical carrier. The specifications of the dosage unit form are determined by and directly depend on: (a) the unique characteristics of Compound 1 and the specific therapeutic effect to be achieved and (b) the inherent limitations in the field of preparing such active compounds for treating individual sensitivity. A person skilled in the art can easily calculate a specific dosage, for example, based on the patient's approximate weight or body surface area or the volume of body space to be occupied. The dosage will also be calculated based on the specific route of administration selected. Further refinement of the calculations required to determine the appropriate dosage for treatment is generally performed by a person skilled in the art. The exact dosage is determined in conjunction with a standard dose response study. It should be understood that the amount of the composition actually administered will be determined by a practicing physician based on relevant circumstances, including one or more conditions to be treated, the choice 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.

[0220] Methods of administration and treatment regimen

[0221] The compounds described herein can be used to prepare a medicament for regulating P2X3, or for treating a disease or condition that benefits at least in part from P2X3 regulation. In addition, a method for treating any disease or condition described herein in a subject in need of such treatment involves administering to the subject a pharmaceutical composition containing at least one compound described herein or a pharmaceutically acceptable salt thereof, or a pharmaceutically acceptable solvate or hydrate thereof in a therapeutically effective amount.

[0222] Compositions containing one or more compounds described herein can be administered for preventive and / or therapeutic treatments. In therapeutic applications, the composition is administered to a patient already suffering from a disease or condition in an amount sufficient to cure or at least partially inhibit the symptoms of the disease or condition. The amount effective for this use will depend on the severity and course of the disease or condition, previous therapy, the patient's health, weight and response to drugs, and the judgment of the attending physician.

[0223] In preventive applications, compositions containing the compounds described herein are administered to a patient susceptible to or otherwise at risk for 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 a patient, the effective amount for this use will depend on the severity and course of the disease, disorder or condition, previous therapy, the patient's health and response to drugs, and the judgment of the attending physician.

[0224] In the event that the patient's condition does not improve, at the physician's discretion, administration of the compound may be administered chronically, i.e., for an extended period of time, including throughout the patient's life span, in order to ameliorate or otherwise control or limit the symptoms of the patient's disease or condition.

[0225] In the event that the patient's condition does improve, at the physician's discretion, administration of the compound may be given continuously; alternatively, the dose of the administered drug may be temporarily reduced or temporarily suspended for a certain length of time (i.e., a "drug holiday"). The length of a drug holiday may vary between 2 days and 1 year, including, by way of example only, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 10 days, 12 days, 15 days, 20 days, 28 days, 35 days, 50 days, 70 days, 100 days, 120 days, 150 days, 180 days, 200 days, 250 days, 280 days, 300 days, 320 days, 350 days, or 365 days. The dose reduction during a drug holiday can be from about 10% to about 100%, including, by way of example only, 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%.

[0226] Once the patient's condition improves, a maintenance dose is administered if necessary. Subsequently, depending on the symptoms, the dosage or frequency of administration, or both, may be reduced to a level that maintains the improved disease, disorder, or condition. However, on a long-term basis upon any recurrence of symptoms, the patient may require long-term intermittent treatment.

[0227] The amount of a given medicament corresponding to such an amount will vary according to factors such as the specific compound, the disease or condition and its severity, the characteristics of the subject or host to be treated (e.g., body weight), but can still be determined in a manner recognized in the art according to the specific circumstances surrounding the case, including, for example, the specific medicament administered, the route of administration, the condition treated, and the subject or host treated. However, in general, the dosage for adult treatment is usually in the range of about 0.01 mg per day to about 5000 mg per day, in some embodiments, about 1 mg per day to about 1500 mg per day. The desired dosage can be conveniently provided in a single dose or administered as divided doses simultaneously (or over a short period of time) or at appropriate intervals, such as two, three, four or more divided doses per day.

[0228] The pharmaceutical compositions described herein can be unit dosage forms suitable for single administration of precise dosages. In unit dosage forms, the preparation is divided into unit doses containing an appropriate amount of one or more compounds. The unit dose can be a packaged form of a preparation containing a discrete amount. Non-limiting examples are packaged tablets or capsules, and powders in vials, capsules, bottles, or ampoules. The aqueous suspension composition can be packaged in a single dose non-reclosable container. Alternatively, a multi-dose reclosable container can be used, in which case a preservative is generally included in the composition. For example only, preparations for parenteral injection can be present in unit dosage forms (which include but are not limited to ampoules or multi-dose containers) and are added with a preservative. Example

[0229] All chemicals, reagents, and solvents were purchased from commercial sources and used without further purification when obtained.

[0230] Example 1: Synthesis of (S)-methyl 2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylate (Compound 1)

[0231]

[0232] Step 1: To a mixture of (S)-3,5-difluoro-4-(3-(4-(methoxycarbonyl)morpholin-2-yl)propanoyl)benzoic acid in 5V THF was added 2 equivalents of CDI at 20-30°C. The reaction mixture was stirred for 0.5-1 hour. 2.5 equivalents of DIPEA were then added dropwise, followed by 2.0 equivalents of MeNH2.HCl in batches. The reaction mixture was stirred at this temperature for 2-4 hours, and then quenched by adding 2.5V H2O dropwise 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 solvent of the organic layer was then replaced with EtOAc. The mixture was then stirred at 45-55°C for 1-2 hours, and then at 20-30°C for 1-2 hours. The resulting suspension was further cooled to 0-10°C and stirred at this temperature for 1-2 hours. The mixture was filtered and the wet cake was slurried in EtOAc. The mixture was then filtered and the wet cake was dried under vacuum at 35-55°C to give the intermediate (S)-2-(3-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-3-oxopropyl)morpholine-4-carboxylic acid methyl ester. LCMS (ESI, m / z): 371.1 [M+H] + . 1H NMR (400MHz, CDCl3) δ1.77-1.99(m,2H),2.67(br s,1H),2.91-3.10(m,6H),3.36-3.52(m,2H),3.72(s,3H),3.79-4.05(m,3H),6.25(br s,1H),7.31-7.40(m,2H).

[0233] Step 2: NBS (1.0 eq) was added to a solution of (S)-2-(3-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-3-oxopropyl)morpholine-4-carboxylic acid methyl ester in DCM. The reaction mixture was cooled to -5 to 5°C, and trifluoromethanesulfonic acid (1.0 eq.) was then added dropwise. The mixture was stirred at 25-30°C, and after completion of the reaction, 7% NaHCO3 aqueous solution was added at -5 to 5°C, and then ascorbic acid was added to adjust pH=5-6. The layers were separated, and the aqueous layer was then back-extracted twice with DCM. The combined organic layers were washed with water, and the resulting DCM solution of (2S)-2-(2-bromo-3-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-3-oxopropyl)morpholine-4-carboxylic acid methyl ester was used directly in the next step. LCMS (ESI, m / z): 449.2 and 451.1 [M+H] + . 1 H NMR (400MHz, CDCl3) δ1.57(br s,1H),2.04-2.24(m,1H),2.25-2.40(m,1H),2.56(brdd,J=13.51,10.38Hz,1H),2.77(br d,J=3.75Hz,1H),2.88-3.11(m,4H),3.35-3.59(m,2H),3.61-3.78(m,4H),3 .80-4.18(m,3H),5.18(td,J=10.19,3.50Hz,1H),6.08-6.65(m,1H),7.38(br t,J=7.38Hz,2H).

[0234] 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. 4-Methylpyridin-2-amine (10.0 eq) was added to the resulting solution and the reaction mixture was heated to 30°C and stirred at this temperature for 24 h. The reaction mixture was then heated to 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. DCM was added to the aqueous layer and the pH was adjusted to 3.0-3.5 with H2SO4 at 0-10°C. The layers were separated. DCM was added to the aqueous layer and the pH was adjusted to 2.0-2.5 with H2SO4 at 0-10°C. The layers were separated. The combined organic layer is concentrated, and the solvent is switched to THF. 10% NaOH aqueous solution (1.5eq) and NaBH4 (0.45eq) are added to the obtained THF solution. The mixture is stirred at 20 ° C for 2-5 hours. The reaction mixture is quenched with water at 0-10 ° C, and extracted with MTBE and then with DCM. DCM is added to the aqueous layer, and the pH is adjusted to 5.6-5.8 with 2N HCl at 0-10 ° C. Each layer is separated, and the aqueous layer is extracted three times with DCM. The combined organic layer is concentrated, and the solvent is switched to MeOH. The resulting mixture is stirred at 55-65 ° C for 0.5h, then cooled to -5-5 ° C and stirred at this temperature for 2h. Water (10V) is added dropwise and the mixture is stirred at this temperature for 3h. The suspension is filtered and the wet cake is washed with water, and then dissolved in MeOH (7V). The solution is heated to 55-65 ° C for 1h, then cooled to 20-30 ° C. The mixture is partially concentrated and then cooled to -5-5 ° C. Water was added dropwise at -5-5°C and the mixture was stirred at this temperature for 1 h. The suspension was filtered and the resulting wet cake was washed with water and then dried under vacuum at 55-65°C to give (S)-methyl 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 (400MHz, DMSO-d6) δppm 2.38 (s, 3H), 2.82 (d, J = 4.27Hz, 4H), 2.98-3.09 (m, 2H), 3.22 (td, J = 11.67, 2.76Hz, 1H), 3.47 (br d,J=3.51Hz,1H),3.55(s,3H),3.62(br d,J=9.29Hz,2H),3.73(br d,J=12.30Hz,1H),6.84(dd,J=7.03,1.51Hz,1H),7.35(s,1H),7.65(d,J=8.03Hz,2H),8.42(d,J=7.03Hz,1H),8.69(br d,J=4.52Hz,1H).

[0235] Example 2: Potency and selectivity of human P2X3 and P2X2 / 3 receptors

[0236] The ability of Compound 1 described herein to act as an antagonist of P2X3 and P2X2 / P2X3 channels (encoded by human P2RX2 and P2RX3 genes, stably expressed in HEK293 cells) was evaluated using the Fluo-8 calcium assay. Compound 1 was evaluated at 12 concentrations.

[0237] To evaluate the antagonist effect, cells were pre-incubated with compound 1 for 20 min and then stimulated with P2X3 and the P2X2 / P2X3 agonist α,β-methylene ATP (meATP) at final concentrations of 3 μM and 30 μM. Ionomycin was added at a final concentration of 5 μM 4 min 50 s after the addition of meATP to obtain maximal calcium influx and possible fluorescence signals from the cells. Fluorescence was recorded continuously for 10 min starting 10 s before the addition of meATP. The IC 50 This indicates that compound 1 is a selective P2X3 antagonist (P2X3 IC 50 =11nM; P2X2 / 3IC 50 >30 μM).

[0238] The examples and embodiments described herein are for illustrative purposes only, and in some embodiments, various modifications or changes are intended to be included within the scope of the disclosure and the scope of the appended claims.

Claims

1. A method for preparing (S)-methyl 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: Reaction with 2,2,6,6-tetramethylpiperidinyl 1-oxyl or T3P generates compounds with the following structure: B) Then a compound having the following structure: It reacts with a mixture of potassium carbonate and potassium bicarbonate or with potassium phosphate to produce a compound with the following structure: C) Then a compound having the following structure: Reaction with palladium on carbon and hydrogen produces a compound with the following structure: D) Then a compound having the following structure: Reaction with hydrogen chloride in ethyl acetate generates a compound with the following structure: E) Then a compound having the following structure: It reacts with methyl chloroformate and aqueous sodium bicarbonate to produce a compound with the following structure: F) Then a compound having the following structure: It reacts with carbonyldiimidazole and methylamine or methylamine hydrochloride to generate a compound with the following structure: G) Then a compound having the following structure: Reaction with N-bromosuccinimide and trifluoromethanesulfonic acid produces a compound with the following structure: H) Then a compound having the following structure: Reaction with 4-methylpyridin-2-amine generates a compound with the following structure:

2. A method for preparing (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-methylformate (Compound 1), comprising: A) A compound having the following structure: Reaction with tosyl chloride and triethylamine produces a compound with the following structure: B) Then a compound having the following structure: Reaction with dimethyl malonate, potassium iodide and cesium carbonate produces a compound with the following structure: C) Then a compound having the following structure: Reaction with triethylamine / magnesium chloride produces a compound with the following structure: D) Then a compound having the following structure: It reacts with lithium chloride and acetic acid to produce a compound with the following structure: E) Then a compound having the following structure: It reacts with aqueous sodium hydroxide to produce a compound with the following structure: F) Then a compound having the following structure: Reaction with hydrogen chloride in ethyl acetate generates a compound with the following structure: G) Then a compound having the following structure: It reacts with methyl chloroformate and aqueous sodium bicarbonate to produce a compound with the following structure: H) Then a compound having the following structure: It reacts with carbonyldiimidazole and methylamine or methylamine hydrochloride to generate a compound with the following structure: I) then a compound having the following structure: Reaction with N-bromosuccinimide and trifluoromethanesulfonic acid produces a compound with the following structure: J) Then the compound having the following structure: Reaction with 4-methylpyridin-2-amine generates a compound with the following structure:

3. Preparation of (S)-2-((2-(2,6-difluoro-4-(methylcarbamoyl)phenyl)-7-methylimidazo[1,2-a]pyridin-3-yl)methyl)morpholine-4-carboxylic acid methyl ester (Compound 1): Included are compounds having the following structure: The mixture is contacted with 4-methylpyridin-2-amine in the presence of a solvent.

4. The method of claim 3, wherein the solvent is acetonitrile or aqueous acetonitrile.

5. The method of claim 3 or claim 4, wherein the compound has the following structure: is by including a compound having the following structure: Prepared by contacting with a brominating agent.

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

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

8. The method of any one of claims 3-7, wherein the compound has the following structure: is by including a compound having the following structure: The compound is prepared by contacting an amide coupling reagent with methylamine or a methylamine salt.

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

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

11. The method of claim 3 or claim 4, wherein the compound has the following structure: is by including a compound having the following structure: The compound is prepared by contacting an amide coupling reagent with methylamine or a methylamine salt.

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

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

14. The method of any one of claims 11-13, wherein the compound has the following structure: is by including a compound having the following structure: Prepared by contacting with a brominating agent.

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

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

17. The method of any one of claims 3-16, wherein the compound has the following structure: is by including a compound having the following structure: Prepared by contacting with methyl chloroformate and base.

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

19. The method of any one of claims 3-18, wherein the compound has the following structure: is by including a compound having the following structure: The invention relates to a method for preparing a polyisocyanate by contacting the polyisocyanate with a deprotecting agent selected from the group consisting of: 1) hydrogen chloride in the presence of a solvent, 2) trifluoroacetic acid, and 3) phosphoric acid.

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

21. The method of any one of claims 3-20, wherein the compound has the following structure: is by including a compound having the following structure: The invention is prepared by a method of contacting with a hydrogenation catalyst and hydrogen.

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

24. The method of any one of claims 3-23, wherein the compound has the structure: is by including a compound having the following structure: With a compound having the following structure: Prepared by contacting with base.

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

26. The method of any one of claims 3-25, wherein the compound has the structure: is by including a compound having the following structure: Prepared by a method of contacting with an oxidant.

27. The method of claim 26, wherein the oxidizing agent is selected from the group consisting of 2,2,6,6-tetramethylpiperidinyl 1-oxyl, T3P, and trichloroisocyanuric acid (TCCA).

28. The method of any one of claims 3-20, wherein the compound has the structure: is by including a compound having the following structure: The compound is prepared by contacting the compound with a base in a solvent.

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

30. The method of claim 28 or claim 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 28-30, wherein the solvent is isopropanol.

32. The method of any one of claims 28-31, wherein the compound has the structure: is by including a compound having the following structure: Prepared by contacting with lithium chloride and acetic acid.

33. The method of any one of claims 28-32, wherein the compound has the structure: is by including a compound having the following structure: With a compound having the following structure: and a base in the presence of a solvent.

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

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

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

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

38. The method of any one of claims 33-37, wherein the compound has the structure: is by including a compound having the following structure: Prepared by contacting with dimethyl malonate, potassium iodide and base.

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

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

41. The method of any one of claims 33-40, wherein the compound has the structure: is by including a compound having the following structure: It can be prepared by contacting toluenesulfonyl chloride and a base in the presence of a solvent.

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

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

44. A compound having the structure: or a pharmaceutically acceptable salt or co-crystal thereof.

45. A compound having the structure: or a pharmaceutically acceptable salt or co-crystal thereof.

46. ​​A compound having the structure: or a pharmaceutically acceptable salt thereof.

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