Deuterated (trifluoromethyl)pyrimidin-2-amine compounds as potentiators of the HMRGX1 receptor

Abstract

The present invention provides compounds of formula I: [Formula 1] TIFF2024540348000035.tif25128 or a pharma- ceutically acceptable salt thereof.

Description

[Technical field]

[0001] The present invention relates to compounds that are potentiators of the hMrgX1 receptor, pharmaceutical compositions containing the compounds, methods of treating pain using the compounds, and intermediates and processes useful in the synthesis of the compounds.

[0002] It is estimated that approximately 20% of adults in the United States suffer from chronic pain. Chronic pain is one of the most common reasons adults seek medical care and is associated with limited mobility and daily activities. Unfortunately, chronic pain is often refractory to current therapies, and many analgesics are associated with dose-limiting adverse events or serious risks of addiction and abuse, which can be substantial barriers to their use in the treatment of chronic pain.

[0003] US Patent No. 6,326,368 discloses certain 2-aryloxy and 2-arylthio substituted pyrimidines and triazines and their derivatives as corticotropin releasing factor (CRF) receptor antagonists useful for treating various disorders such as depression, anxiety, drug addiction, and inflammatory disorders. US Patent No. 5,100,459 discloses certain substituted sulfonylureas and their intermediates. W. Wangdong, et.al., ChemMedChem, vol 10(1), 57-61 (2015) discloses 2-(cyclopropanesulfonamido)-N-(2-ethoxyphenyl)benzamide, ML382, as a potent and selective positive allosteric modulator of MrgX1. US Patent No. 11,414,389 discloses (trifluoromethyl)pyrimidin-2-amine compounds as enhancers of human MrgX1.

[0004] There is a need for alternative treatments for pain, including chronic pain.In addition, there is a need for compounds that are potentiators of hMrgX1 receptor.Furthermore, it is desirable for hMrgX1 receptor potentiators to have certain properties that make them suitable for administration to humans, including favorable pharmacokinetic properties, such as favorable metabolic properties.In addition, it is desirable for hMrgX1 receptor potentiators to be CNS penetrating.The present invention provides compounds that address one or more of these needs.

[0005] Thus, in one embodiment, the present invention provides a compound of formula I, [ka] In the formula, R 1 is a compound, [ka] or a pharma- ceutically acceptable salt thereof.

[0006] A particular embodiment is a compound of formula Ia: [ka] or a pharma- ceutically acceptable salt thereof.

[0007] Additionally, a particular embodiment is a compound of formula Ia: [ka]

[0008] A particular embodiment is a compound of formula Ib: [ka] or a pharma- ceutically acceptable salt thereof.

[0009] Additionally, a particular embodiment is a compound of formula Ib: [ka]

[0010] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 20%, or a pharma- ceutically acceptable salt thereof.

[0011] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 30%, or a pharma- ceutically acceptable salt thereof.

[0012] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 40%, or a pharma- ceutically acceptable salt thereof.

[0013] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 50%, or a pharma- ceutically acceptable salt thereof.

[0014] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 60%, or a pharma- ceutically acceptable salt thereof.

[0015] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 70%, or a pharma- ceutically acceptable salt thereof.

[0016] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 80%, or a pharma- ceutically acceptable salt thereof.

[0017] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 85%, or a pharma- ceutically acceptable salt thereof.

[0018] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 90%, or a pharma- ceutically acceptable salt thereof.

[0019] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 93%, or a pharma- ceutically acceptable salt thereof.

[0020] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 95%, or a pharma- ceutically acceptable salt thereof.

[0021] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 99%, or a pharma- ceutically acceptable salt thereof.

[0022] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 20%.

[0023] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 30%.

[0024] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 40%.

[0025] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 50%.

[0026] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 60%.

[0027] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 70%.

[0028] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 80%.

[0029] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 85%.

[0030] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 90%.

[0031] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 93%.

[0032] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 95%.

[0033] In certain embodiments, each position designated as D in Formula I, Ia, or Ib has a deuterium enrichment of at least 99%.

[0034] In one embodiment, the present invention also provides a method for treating pain in a patient in need of such treatment, comprising administering to the patient an effective amount of a compound of formula I, Ia, or Ib, or a pharma- ceutically acceptable salt thereof. In one embodiment, the present invention further provides a method for treating chronic pain in a patient in need of such treatment, comprising administering to the patient an effective amount of a compound of formula I, Ia, or Ib, or a pharma- ceutically acceptable salt thereof. In one embodiment, the present invention further provides a method for treating chronic lower back pain in a patient in need of such treatment, comprising administering to the patient an effective amount of a compound of formula I, Ia, or Ib, or a pharma- ceutically acceptable salt thereof. In one embodiment, the present invention further provides a method for treating diabetic peripheral neuropathy pain in a patient in need of such treatment, comprising administering to the patient an effective amount of a compound of formula I, Ia, or Ib, or a pharma- ceutically acceptable salt thereof. In one embodiment, the invention further provides a method of treating osteoarthritis pain in a patient in need of such treatment, comprising administering to the patient an effective amount of a compound of Formula I, Ia, or Ib, or a pharma- ceutically acceptable salt thereof.

[0035] In one embodiment, the present invention further provides a compound of formula I, Ia, or Ib, or a pharma- ceutically acceptable salt thereof, for use in therapy. In one embodiment, the present invention provides a compound of formula I, Ia, or Ib, or a pharma- ceutically acceptable salt thereof, for use in the treatment of pain. In one embodiment, the present invention provides a compound of formula I, Ia, or Ib, or a pharma- ceutically acceptable salt thereof, for use in the treatment of chronic pain. In one embodiment, the present invention provides a compound of formula I, Ia, or Ib, or a pharma- ceutically acceptable salt thereof, for use in the treatment of chronic lower back pain. In one embodiment, the present invention provides a compound of formula I, Ia, or Ib, or a pharma- ceutically acceptable salt thereof, for use in the treatment of diabetic peripheral neuropathy pain. In one embodiment, the present invention provides a compound of formula I, Ia, or Ib, or a pharma- ceutically acceptable salt thereof, for use in the treatment of osteoarthritis pain.

[0036] In one embodiment, the present invention also provides the use of a compound of formula I, Ia, or Ib, or a pharma- ceutically acceptable salt thereof, for the manufacture of a medicament for treating pain. In one embodiment, the present invention provides the use of a compound of formula I, Ia, or Ib, or a pharma- ceutically acceptable salt thereof, for the manufacture of a medicament for treating chronic pain. In one embodiment, the present invention provides the use of a compound of formula I, Ia, or Ib, or a pharma- ceutically acceptable salt thereof, for the manufacture of a medicament for treating chronic lower back pain. In one embodiment, the present invention provides the use of a compound of formula I, Ia, or Ib, or a pharma- ceutically acceptable salt thereof, for the manufacture of a medicament for treating diabetic peripheral neuropathy pain. In one embodiment, the present invention provides the use of a compound of formula I, Ia, or Ib, or a pharma- ceutically acceptable salt thereof, for the manufacture of a medicament for treating osteoarthritis pain.

[0037] In one embodiment, the present invention further provides a pharmaceutical composition comprising a compound of formula I, Ia, or Ib or a pharma- ceutically acceptable salt thereof together with one or more pharma- ceutically acceptable carriers, diluents, or excipients. In one embodiment, the present invention further provides a pharmaceutical composition comprising a compound of formula I, Ia, or Ib together with one or more pharma- ceutically acceptable carriers, diluents, or excipients. In one embodiment, the present invention further provides a process for preparing a pharmaceutical composition comprising mixing a compound of formula I, Ia, or Ib or a pharma- ceutically acceptable salt thereof with one or more pharma- ceutically acceptable carriers, diluents, or excipients. In one embodiment, the present invention further provides a process for preparing a pharmaceutical composition comprising mixing a compound of formula I, Ia, or Ib with one or more pharma- ceutically acceptable carriers, diluents, or excipients. In one embodiment, the present invention also encompasses novel intermediates and processes for the synthesis of compounds of formula I, Ia, or Ib.

[0038] As used herein, the terms "treating," "treatment," or "treat" include inhibiting, slowing, arresting, or ameliorating the progression or severity of an existing condition or disorder.

[0039] As used herein, the term "patient" refers to mammals, particularly humans.

[0040] As used herein, the term "effective amount" refers to an amount or dosage of a compound of the present invention, or a pharma- ceutically acceptable salt thereof, that upon single or multiple administration to a patient, provides the desired effect in the patient being diagnosed or treated.

[0041] Effective amounts can be determined by those skilled in the art by using known techniques and observing results obtained under similar circumstances. In determining the effective amount for a patient, the attending physician will take into account several factors, including the patient's species; its size, age, and general health; the specific disease or disorder involved; the extent or involvement or severity of the disease or disorder; the response of the individual patient; the specific compound administered; the mode of administration; the bioavailability characteristics of the administered preparation; the selected dosage regimen; the use of concomitant drugs; and other relevant circumstances.

[0042] As used herein, the symbol "D" refers to a deuterium atom.

[0043] As used herein, "deuterium enrichment" refers to the percentage of deuterium atoms incorporated at a given position in a compound of formula I, Ia, or Ib, instead of hydrogen atoms. For example, at least 90% deuterium enrichment at a particular position means that 90% or more of the molecules in a sample contain deuterium at the particular position. The deuterium enrichment of a sample can be determined using standard analytical techniques and methods well known to those skilled in the art, including, but not limited to, mass spectrometry and nuclear magnetic resonance spectroscopy. In addition, unless otherwise specified, when a position is specifically designated as "D" or "deuterium", the position is understood to have a deuterium enrichment of at least 20%.

[0044] As used herein, "C 1~4"Alkyl" refers to an alkyl substituent having 1 to 4 carbon atoms which may be branched or unbranched and includes, for example, methyl, ethyl, propyl, isopropyl, butyl, and the like, with methyl and ethyl being preferred.

[0045] As used herein, "aryl" refers to a carbocyclic aromatic substituent containing 6 carbon atoms, which may be unsubstituted or substituted, and includes phenyl, 4-methyl-phenyl, and the like.

[0046] As used herein, "tosylate" refers to a p-toluenesulfonate substituent.

[0047] The compounds of the present invention are formulated as pharmaceutical compositions to be administered by any route that makes the compounds bioavailable. More preferably, such compositions are for oral administration. Such pharmaceutical compositions and processes for their preparation are well known in the art (e.g., Remington: The Science and Practice of Pharmacy, A. Adejare, Editor, 23rd Edition). nd Edition, published 2020, Elsevier Science).

[0048] Pharmaceutically acceptable salts of the compounds of the present invention can be formed, for example, by reaction of a suitable free base of the compounds of the present invention with a suitable pharma- ceutically acceptable acid in a suitable solvent, such as diethyl ether, under standard conditions well known in the art. See, for example, Gould, PL, "Salt selection for basic drugs," International Journal of Pharmaceutics, 33:201-217 (1986); Bastin, RJ, et al., "Salt Selection and Optimization Procedures for Pharmaceutical New Chemical Entities," Organic Process Research and Development, 4:427-435 (2000); and Berge, SM, et al., "Pharmaceutical Salts," Journal of Pharmaceutical Sciences, 66:1-19, (1977).

[0049] Certain abbreviations are defined as follows: "ACN" refers to acetonitrile, "MTBE" refers to methyl tert-butyl ether, "THF" refers to tetrahydrofuran, "DMF" refers to dimethylformamide, "EtOAc" refers to ethyl acetate, "BAM8-22" refers to bovine adrenal medulla peptide 8-22, "Cat.#" refers to catalog number, "CRC" refers to concentration-response curve, "DMEM" refers to Dulbecco's modified eagle media, "DMSO" refers to dimethyl sulfoxide, "DPBS" refers to Dulbecco's phosphate-buffered saline, and "EC 50" refers to the effective concentration of a drug that gives a half-maximal response between baseline and maximum after a specific exposure time, "EDTA" refers to ethylenediaminetetraacetic acid, "ESMS" refers to electrospray mass spectrometry, "FBS" refers to fetal bovine serum, "g" refers to grams, "h" refers to hours, "HEC" refers to hydroxyethylcellulose, "HEK293" refers to human embryonic kidney 293 cells, "HEPES" refers to (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid), "hMrgX1" refers to the human MrgX1 receptor, and "HTRF" refers to homogeneous time resolved fluorescence. "IP1" stands for inositol monophosphate, and "K p,uu" refers to unbound brain-to-plasma partition coefficient, "LC-ESMS" refers to Liquid Chromatography Electrospray Mass Spectrometry, "min" refers to minute, "mL" refers to milliliter, "mol" refers to mole, "mmol" refers to millimole, "nm" refers to nanometer, "nmol" refers to nanomole, "m / z" refers to mass-to-charge ratio for mass spectrometry, "n" refers to the number or number of runs tested, in the context of biological data, "PBS" refers to phosphate-buffered saline, "rpm" refers to revolutions per minute, "SD" refers to standard deviation, "SEM" refers to standard error of the mean, "U / mL" refers to units per milliliter, and "V" refers to volume, in the context of a solvent.

[0050] The compounds of the present invention or salts thereof may be prepared by various procedures known to those skilled in the art, some of which are illustrated in the following schemes, preparations, and examples. Those skilled in the art will recognize that the specific synthetic steps for each of the described routes can be combined in different ways or combined with steps from different schemes to prepare the compounds of the present invention or salts thereof. The products of each step in the following schemes can be recovered by conventional methods well known in the art, including extraction, evaporation, precipitation, chromatography, filtration, trituration, and crystallization. In the following schemes, all substituents are as previously defined unless otherwise indicated. The reagents and starting materials are readily available to those skilled in the art. The following schemes, preparations, examples, and assays further illustrate the present invention, but should not be construed as limiting the scope of the present invention in any way.

[0051] Scheme 1 [ka] R 1 OH is: [ka]

[0052] In Scheme 1, Step A, LG is a suitable leaving group, such as F, Cl, Br, I, tosylate, or -SO2R a where R a A compound of structure (1), where C is aryl or alkyl, e.g., phenyl or methyl (preferably Cl, e.g., 4-chloro-6-(trifluoromethyl)pyrimidin-2-amine), is dissolved in a suitable organic solvent, such as ACN, with stirring under an inert atmosphere, such as nitrogen, and then treated with about 1.1 equivalents of 3-dibromo-5,5-dimethyl-imidazolidine-2,4-dione. The reaction is stirred for about 12-24 hours. The product is then isolated using techniques well known in the art, such as dilution with water, extraction with a suitable organic solvent, such as EtOAc, drying the combined organic extracts over sodium sulfate, filtration, and concentration under reduced pressure to provide a compound of structure (2).

[0053] In scheme 1, step B, the compound of structure (2) is combined with about 1.1 equivalents of the compound of structure (3) in a suitable organic solvent such as ACN. The mixture is then treated with about 1.5 equivalents of a suitable base, such as cesium carbonate or potassium carbonate, and the reaction mixture is heated to reflux for about 3 hours. The reaction is then cooled to room temperature, and the product is isolated using standard techniques well known in the art, such as dilution with water, extraction with a suitable organic solvent such as EtOAc or MTBE, drying the combined organic extracts over sodium sulfate, filtration, and concentration under reduced pressure to obtain the compound of structure (4). This material can be purified using flash chromatography on silica gel with a suitable eluent such as EtOAc:hexane to obtain the purified compound of structure (4).

[0054] In Scheme 1, Step C, the compound of structure (4) is combined with about 1.25 equivalents of 5-(trideuteriomethyl)-1-aza-5-stannabicyclo[3.3.3]undecane and about 0.05 equivalents of a suitable catalyst, such as bis(tri-tert-butylphosphine)palladium(0), in an oven-dried Biotage 10-20 mL microwave vial containing a stir bar under an inert atmosphere, such as nitrogen. A suitable organic solvent, such as DMF, is added, the vial is capped, and heated at about 100° C. with stirring for about 1-2 hours. The reaction mixture is then combined with a suitable solvent mixture, such as MTBE and 1M aqueous KF. The organics are then separated and washed successively with 1M aqueous KF, water, and saturated aqueous NaCl. The organics are then dried over MgSO4, filtered, and the filtrate is concentrated under reduced pressure to provide the crude compound of formula I. This crude material is then purified using standard techniques well known in the art, for example, chromatography on silica gel with a suitable eluent such as EtOAc:hexanes, to provide purified compounds of Formula I, including within its scope Formula Ia and Formula Ib. One skilled in the art will recognize that the deuterium enrichment of the reagent used in this Step C, 5-(trideuteriomethyl)-1-aza-5-stannabicyclo[3.3.3]undecane, determines the deuterium enrichment of the final compounds of Formula I, Ia, and Ib.

[0055] Preparation 1 5-(Trideuteriomethyl)-1-aza-5-stannabicyclo[3.3.3]undecane [ka] 5-Chloro-1-aza-5-stannabicyclo[3.3.3]undecane (2.03 g, 6.90 mmol) and THF (50 mL) were added to an oven-dried flask containing a stir bar under nitrogen. The resulting slurry was cooled in a dry ice / ACN bath and methyl-d3-magnesium iodide (1 M in diethyl ether, 14 mL, 14 mmol, >99% deuterium enriched) was added over 10 min. The mixture was stirred in the dry ice / ACN bath for 2.5 h and then in the ice bath for 20 min. After 35 min, the ice bath was removed and the mixture was poured into a separatory funnel with water (100 mL) and MTBE (100 mL). The organic layer was further washed with brine (100 mL), dried over MgSO4, filtered and evaporated. The residue was dried under vacuum to give the title compound as a white solid, 1.71 g. 1 H and 13 The C NMR data was in general agreement with that reported in Angew. Chem. Int. Ed. 2015, 54, 5488-5492.

[0056] Preparation 2 5-Bromo-4-chloro-6-(trifluoromethyl)pyrimidin-2-amine [ka] Scheme 1, Step A: A room temperature solution of 4-chloro-6-(trifluoromethyl)pyrimidin-2-amine (20 g, 98.2 mmol) in ACN (200 mL) was treated portionwise with 1,3-dibromo-5,5-dimethyl-imidazolidine-2,4-dione (31.52 g, 108 mmol) and the reaction was stirred under nitrogen overnight. An orange slurry formed which was diluted with water and extracted three times with ethyl acetate. The organic extracts were combined and dried over sodium sulfate. Filtration and evaporation of the resulting filtrate under reduced pressure gave a crude solid which was triturated in hexane / ethyl acetate and filtered to give the title compound (13.82 g, 54% yield). ESMS (m / z, 79 Br / 81 Br):370 / 372[M+H].

[0057] Preparation 3 5-Bromo-4-(2,6-difluorophenoxy)-6-(trifluoromethyl)pyrimidin-2-amine [ka] Scheme 1, Step B: 5-Bromo-4-chloro-6-(trifluoromethyl)pyrimidin-2-amine (19.46 g, 69 mmol) and 2,6-difluorophenol (9.87 g, 75.9 mmol) were combined in ACN (200 mL). Cesium carbonate (33.72 g, 103.5 mmol) was added and heated to reflux for 3 h. The reaction mixture was cooled, diluted with water and extracted three times with ethyl acetate. The organic extracts were combined and dried over sodium sulfate. Filtration and evaporation of the resulting filtrate under reduced pressure gave a crude solid which was purified by flash chromatography on silica gel eluting with 5-100% ethyl acetate in hexane to give the title compound (16.57 g, 61% yield) after solvent evaporation of the desired chromatographic fractions. ESMS (m / z, 79 Br / 81 Br):274 / 276[MH].

[0058] Preparation 4 4-((2-amino-5-bromo-6-(trifluoromethyl)pyrimidin-4-yl)oxy)-3,5-difluorobenzonitrile

[0059] TIFF0007656780000012.tif28128 Scheme 1, Step B: 5-Bromo-4-chloro-6-(trifluoromethyl)pyrimidin-2-amine (2.01 g, 7.27 mmol), 3,5-difluoro-4-hydroxy-benzonitrile (2.25 g, 14.5 mmol), potassium carbonate (2.02 g, 14.6 mmol), and DMF (20 mL) were placed in a flask equipped with a stir bar and heated on a stir block at 80 °C for 3 h. The mixture was cooled to room temperature and then added to a separatory funnel along with water and MTBE. The organic layer was then washed with two more portions of water followed by saturated aqueous sodium chloride. The organics were dried over Na2SO4 and evaporated. The product was then purified by flash chromatography on silica gel using 0% to 30% ethyl acetate in hexanes. After concentration of the product fractions, the residue was repurified by flash chromatography on silica gel using 0% to 30% MTBE in hexanes. Evaporation of the desired fractions gave the title compound as 2.50 g of a white solid. ESMS (m / z, 79 Br / 81 Br):395 / 397[M+H].

[0060] Example 1 4-[2-amino-5-(trideuteriomethyl)-6-(trifluoromethyl)pyrimidin-4-yl]oxy-3,5-difluoro-benzonitrile [ka] Scheme 1, step C: 4-((2-amino-5-bromo-6-(trifluoromethyl)pyrimidin-4-yl)oxy)-3,5-difluorobenzonitrile (600 mg, 1.52 mmol), 5-(trideuteriomethyl)-1-aza-5-stannabicyclo[3.3.3]undecane (530 mg, 1.91 mmol; at least 95% deuterium enriched in each deuterium) and bis(tri-tert-butylphosphine)palladium(0) (45 mg, 0.088 mmol) were added as solids under nitrogen to an oven-dried Biotage 10-20 mL microwave vial containing a stir bar. DMF (9.0 mL) was added and the vial was capped. The vial was heated in a 100 °C block with stirring for 105 min. The mixture was then added to a separatory funnel along with MTBE (100 mL) and 1 M aqueous KF solution (100 mL). The organics were separated and then washed successively with 1M aqueous KF (100 mL), water (100 mL), and brine (100 mL). The organics were dried over MgSO4 and filtered through a 1-inch silica plug. The plug was rinsed with MTBE, and the combined filtrates were evaporated. The residue was dissolved in DCM and adsorbed onto silica gel. The product was then purified by chromatography on silica gel using 20%-30% ethyl acetate in hexanes. Evaporation of the desired fractions followed by drying under vacuum at 60° C. afforded the title compound as 327 mg of a white solid. Deuterium enrichment of at least 95% at each deuterium; ESMS (m / z): 334 [M+H].

[0061] After purification, one batch of the compound of Example 1 was subjected to proton NMR to quantify deuterium incorporation. The signal from the methyl group was integrated to <0.005, compared to a value of 3.00 obtained for the protonated group, indicating greater than 99% deuterium incorporation.

[0062] Example 2 4-(2,6-difluorophenoxy)-5-(trideuteriomethyl)-6-(trifluoromethyl)pyrimidin-2-amine [ka] Scheme 1, step C: 5-Bromo-4-(2,6-difluorophenoxy)-6-(trifluoromethyl)pyrimidin-2-amine (576 mg, 1.56 mmol), 5-(trideuteriomethyl)-1-aza-5-stannabicyclo[3.3.3]undecane (535 mg, 1.93 mmol; at least 95% deuterium enriched in each deuterium) and bis(tri-tert-butylphosphine)palladium(0) (57 mg, 0.11 mmol) were added as solids under nitrogen to an oven-dried Biotage 10-20 mL microwave vial containing a stir bar. DMF (9.0 mL) was added and the tube was capped. The vial was heated in a 100 °C block with stirring for 3 h. The mixture was then added to a separatory funnel along with MTBE (100 mL) and 1 M aqueous KF solution (100 mL). The organics were separated and then washed successively with 1M aqueous KF (100 mL), water (100 mL), and brine (100 mL). The organics were filtered through a 1" silica plug. The plug was rinsed with MTBE and the combined filtrates were evaporated. The residue was dissolved in DCM and adsorbed onto silica gel. The product was then purified by chromatography on silica gel using 20%-25% ethyl acetate in hexanes. Evaporation of the desired fractions followed by drying under vacuum at 60°C afforded the title compound as 376 mg of a white solid. Deuterium enrichment of at least 95% at each deuterium; ESMS (m / z): 309 [M+H].

[0063] Scheme 2 [ka]

[0064] Preparation 5 Ethyl 4,4,4-trifluoro-3-oxo-2-(trideuteriomethyl)butanoate [ka] Scheme 2, step D: A mixture of 1,2-dimethoxyethane (2500 mL) and sodium hydride (24 g, 600.1 mmol) was cooled to 0° C. and treated dropwise with a solution of ethyl 4,4,4-trifluoro-3-oxo-butanoate (100 g, 543.15 mmol) in 1,2-dimethoxyethane (300 mL) over 20 min. The mixture was stirred at 25° C. for 30 min, then trideuterio(iodo)methane (158 g, 1090 mmol) was added at 25° C. and the reaction was heated to 90° C. and stirred for 3 h. The reaction was cooled, quenched with aqueous NH4Cl (200 mL) and extracted with MTBE (200 mL×2). The combined organic layers were washed with brine (100 mL) and dried over Na2SO4. The combined organic layers were filtered through filter paper to give a filtrate, which was concentrated under vacuum at 35° C. to give 100 g (91%) of the title product as a yellow oil. 19 F(DMSO-d6)=-81.85ppm

[0065] Preparation 6 2-Amino-5-(trideuteriomethyl)-6-(trifluoromethyl)pyrimidin-4-ol [ka] Scheme 2, Step E: A 0° C. solution of ethyl 4,4,4-trifluoro-3-oxo-2-(trideuteriomethyl)butanoate (60 g, 298.3 mmol) in methanol (600 mL) was treated with guanidine hydrochloride (30 g, 314.0 mmol) followed by a solution of sodium methoxide in methanol (100 mL, 400 mmol) at 25° C. The reaction was heated to 90° C. and stirred for 3 h. The reaction mixture was cooled and concentrated in vacuo to remove methanol. The crude was acidified with acetic acid (27.5 mL, 480 mmol) in water (600 mL) and stirred at 25° C. for 10 min to give a precipitated white solid which was filtered and washed with water (100 mL×2) to give a filter cake which was dried under vacuum at 40° C. to give 41 g (64%) of the title product. ESMS (m / z): 197 [M+H]

[0066] Preparation 7 4-Chloro-5-(trideuteriomethyl)-6-(trifluoromethyl)pyrimidin-2-amine [ka] Scheme 2, Step F: A 0° C. mixture of 2-amino-5-(trideuteriomethyl)-6-(trifluoromethyl)pyrimidin-4-ol (16 g, 81.57 mmol) in acetonitrile (160 mL) was treated with triethylamine (11.4 mL, 81.8 mmol) and then treated dropwise with phosphoryl chloride (8.4 mL, 90 mmol). The reaction was heated to 80° C. and stirred for 12 h. The reaction mixture was concentrated in vacuo to remove phosphoryl chloride to a volume of approximately 100 mL, added dropwise to water (500 mL) and stirred at 25° C. for 0.5 h to give a solid which was filtered and the filter cake was dried under vacuum at 40° C. to give 8 g (45%) of the title product. ESMS (m / z, 35 Cl / 37 Cl):215 / 217[M+H]

[0067] Example 1 (alternative preparation) 4-[2-amino-5-(trideuteriomethyl)-6-(trifluoromethyl)pyrimidin-4-yl]oxy-3,5-difluoro-benzonitrile [ka] Scheme 2, Step G: A solution of 4-chloro-5-(trideuteriomethyl)-6-(trifluoromethyl)pyrimidin-2-amine (37 g, 172.4 mmol) and 3,5-difluoro-4-hydroxybenzonitrile (54 g, 348.15 mmol) in N,N-dimethylacetamide (370 mL) was treated with potassium phosphate tribasic (187 g, 863.3 mmol) and heated to 100° C. for 12 h. The reaction mixture was added dropwise to water (50 V) over 10 min to give a white solid precipitate that was filtered. The filter cake was dried under vacuum to give the crude product, which was triturated in acetonitrile (2 V) and filtered to give 35 g of a solid. The solid was recrystallized with EA (3 V) and heptane (10 V), filtered, and the filter cake was dried under vacuum to give 30 g of a solid, which was recrystallized again with EA (3 V) / heptane (10 V) to give 26 g (45%) of the title product. ESMS (m / z): 344 [M+H].

[0068] EC against hMrgX1 by HTRF 50 IP1 cell assay for determination Cell plating:HEK293 cells stably expressing recombinant human MrgX1 receptor were cultured in growth medium (GIBCO™, Cat. # 11960-04) containing DMEM with glutamine supplemented with 10% heat-inactivated FBS (HyClone™, Cat. # CH30073), 1% penicillin / streptomycin (HyClone™, Cat. # SV30010, 10,000 U / mL penicillin, 10,000 μg / mL streptomycin in 0.85% NaCl), 20 mM HEPES (GIBCO™, Cat. # 15630122), and 0.3 mg / mL G418 (GIBCO™, Cat. # 11811031). 4) in culture flasks (Corning, T150). When the cell monolayer reached a level of 80-90% confluence, the monolayer was washed once with 10 mL of DPBS (HyClone™, Cat. #14190-144) and dissociated using TrypLE™ Express Enzymatic Cell Dissociation Medium (GIBCO™, Cat. #12605-010) and diluted by adding 10 mL of DPBS. The dissociated cells were transferred to a sterile 50 mL conical tube, pelleted by centrifugation at 300 x g to remove the growth and dissociation medium, and diluted to 1 M cells / mL in DMEM for plating.

[0069] Determination of IP1 potency and efficacy: Test compounds were dissolved in DMSO to a concentration of 10 mM and serially diluted in DMSO to obtain a 10-point concentration-response stock dilution plate. Growth medium was removed from the cell plates and the stock 10-point dilution plate was diluted in medium and stamped onto the cell plates at concentrations 2-fold higher than the final test concentration up to 30 μM. The endogenous agonist BAM8-22 (Tocris-BioScience®, Cat. #1763) was used to measure the EC50 concentration, determined independently with a minimum of n=3. 15The anti-IP1 cryptate and d2-labeled IP1 in half the volume of lysis buffer provided by the IP-One Gq Kit (CisBio Cat.#62IPAPEC) were then added to the cell plate to initiate cell lysis and incubated for 60 min at room temperature in the dark. Fluorescence was then determined at 620 and 665 nm (approximately 100 μs after laser excitation).

[0070] Data Analysis: Fluorescence ratios were determined as the ratio of fluorescence emission at 665 nm to 620 nm and converted to IP1 concentrations using an IP1 standard curve generated on a separate plate according to the manufacturer's instructions. IP1 concentrations were then plotted as a function of compound concentration. Enhancer potency (EC 50 ) to E.C. 15 is defined as the compound concentration that results in a 50% increase in IP1 concentration achieved by a saturating concentration of BAM8-22 in the presence of the endogenous agonist BAM8-22, and was determined by using Genedata software (GeneData AG, Basel Switzerland) fitting the following equation to a 10-point CRC: y is the IP1 concentration determined for a given compound concentration, [L] indicates the concentration of the test compound, and Max is the maximum increase achieved by a saturating concentration of BAM8-22. Y=Max * [L] / (EC 50 +[L]) EC 50 Values ​​are reported as geometric means (SEM, n) in nM.

[0071] [Table 1]

[0072] Table 1 shows the relative EC20 values ​​achieved in assays essentially as described above for the compounds of Examples 1 and 2. 50 and maximal stimulation, indicating that these compounds are enhancers of hMrgX1.

[0073] K in mice p,uu,brain In vivo determination of Unbound brain-plasma partition coefficient (K p,uu,brain ) is one of the important pharmacokinetic parameters to assess a compound's ability to cross the blood-brain barrier (BBB). It is typically measured in preclinical species using the following methodology: p,uu,brain Values ​​indicate the percentage of free drug in plasma that distributes across the BBB.

[0074] subject: The subjects of these studies were 12 male CD1 (ICR) mice (Envigo, Indianapolis, IN, USA) aged 5-7 weeks at the time of testing. Mice were housed in groups of 4 in high-density plastic home cages. Food and water were available ad libitum. The room was maintained at 73°F with 30-70% relative humidity and on a 6:00-18:00 light / dark cycle.

[0075] Drugs: The compound of Example 1 was prepared at 10 mg / ml in 1% HEC, 0.25% TWEEN® 80, 0.05% DOWSIL™ vehicle in water. The prepared compound was sonicated in a water bath for 30 min until a suspension was formed. Mice were orally administered a 100 mg / kg dose at 10 ml / kg.

[0076] Dosing and tissue collection: In this experiment, 10 mice were orally administered 100mg / kg of the compound of Example 1. Mice were then euthanized by CO2 asphyxiation 2 hours after administration, plasma samples were collected by cardiac puncture, and mouse brains were removed, weighed, and frozen on dry ice. Blood samples were stored in EDTA tubes on wet ice and centrifuged at 15k rpm for 10min. Plasma was collected, plated in 96-well plates, and frozen at -80℃.

[0077] Pharmacokinetic Sampling:The resulting plasma and brain samples were analyzed for Example 1 using an LC-MS / MS method (Q2 Solutions, Indianapolis, IN, USA). Plasma samples were extracted using protein precipitation. The lower limit of quantification was 25 ng / mL and the upper limit of quantification was 5000 ng / mL. Brain samples were homogenized and analytes were extracted using protein precipitation. The lower limit of quantification was 4 ng / g and the upper limit of quantification was 200000 ng / g.

[0078] Plasma and brain protein binding determinations: Mouse plasma and brain homogenate protein binding was determined in vitro using equilibrium dialysis as described elsewhere (Zamek-Gliszczynski et al., J Pharm Sci, 101:1932-1940, 2012). Results showed that plasma (f u,plasma ) and the brain (f u,brain ) as the unbound fraction and then calculated as K p,uu,brain The f of the mouse in Example 1 is used to calculate u,plasma and f u,brain were determined to be 0.0667 and 0.011, respectively.

[0079] Analysis and Results: K p,uu,brain is calculated at each time point from the following expression, the individual components being derived from a combination of in vitro and in vivo measurements performed as described above:

number

[0080] [Table 2] * As mentioned above, the f of 0.011 for miceu,brain value and ^ f of 0.0667 of mouse u,plasma Use the value.

[0081] The average unbound brain to unbound plasma ratio (Kp,uu-brain) for the compound of Example 1 was 0.586, suggesting that the compound has good penetration into the CNS and that active transport mechanisms are not operative in mouse brain tissue.

[0082] In vitro determination of intrinsic clearance in mouse and human hepatocytes Cryopreserved hepatocytes are used to determine the in vitro metabolic clearance of drug candidates. To compare the compound of Example 1 with its non-deuterated analogue (hereafter referred to as Compound A), the following assay was performed. [ka]

[0083] Compound A is described in US Pat. No. 11,414,389, the entire contents of which are incorporated herein by reference.

[0084] To compare the metabolic clearance of the compound of Example 1 and Compound A, human and mouse cryopreserved hepatocytes were removed from liquid nitrogen storage, thawed in a 37°C water bath, placed in 50mL Cryopreserved Hepatocyte Recovery Media (CHRM), centrifuged at 100×g for 10 minutes for humans and 65×g for mice, and then resuspended in Hepatocyte Maintenance Media (HMM). Compound incubations (0.3 μM substrate concentration) were then performed in a 96-well plate format at 37°C, 200,000 cells / well, with shaking at approximately 600 rpm. Incubations were initiated by directly adding 2 μL of substrate compound. At 0, 15, 30, 60, and 90 minutes, 20 μL of incubation samples were quenched with 80 μL of acetonitrile containing internal standard. The quenched plates were sealed with foil, centrifuged at 4000 rpm for 30 min, and analyzed for substrate by liquid chromatography with tandem mass spectrometry (LC-MS / MS).

[0085] The intrinsic clearance values ​​of the compound of Example 1 and Compound A in mouse and human hepatocytes are shown in Table 3.

[0086] [Table 3]

[0087] Intrinsic clearance is a measure of the maximum potential hepatic metabolism of a compound if not limited by blood flow or protein binding. This intrinsic clearance is expressed as the excretion rate constant (k dep min -1 ) which is determined by the following equation: CL int (μL / min1 / 10 6 cell)=k dep (min -1 ) * 0.2mL incubated / 0.2×10 6 cell *1000 μL / mL was used and was measured from disappearance of substrate over time of incubation.

[0088] Determination of pharmacokinetics in mice subject: Subjects in these studies were male CD-1 mice from either Envigo (Indianapolis, IN, USA) or Charles River Laboratories, Inc. (Raleigh, NC, USA), aged 4-12 weeks at the time of testing. Each dosing group had three animals with free access to food and water.

[0089] Dosing and Sample Collection: Test compounds were administered intravenously (IV) at 1 mg / kg via the tail vein (using vehicle: Dimethylacetamide (DMA) 25% (v / v), EtOH 15% (v / v), Propylene Glycol (PG) 10% (v / v), 2-Pyrrolidone (2-P) 25%, and purified water 25%) and orally (PO) at 10 mg / kg via a gavage needle (using a vehicle of Hydroxyethylcellulose 1% (w / v), Polysorbate 80 0.25% (w / v), Antifoam 1510-US 0.05% (v / v) in sufficient purified water. Dried blood spots were Blood (approximately 20 μL) for collection of DBS (blood spot) was collected from each available animal via the saphenous vein using K2EDTA capillary tubes and stored at ambient temperature until analysis. Serial blood samples are collected at 0.08, 0.25, 0.5, 1, 2, 4, 8, 12, 24, and 48 h after the IV bolus dose and at 0.25, 0.5, 1, 2, 4, 8, 12, 24, and 48 h after oral dosing.

[0090] Sample Analysis:The DBS cards (3 mm punch) of the samples or standards were mixed with 180 uL of methanol:acetonitrile (1 / 1, v / v) solution containing the internal standard, respectively, to extract the analytes, followed by 2-fold dilution with water. 10 uL aliquots of the samples or standards were analyzed using the LC-MS / MS method. For compound A, the lower limit of quantification (LLQ) was 5 ng / mL, and the upper limit of quantification (ULQ) was 2500 ng / mL. For the compound of Example 1, the LLQ was 10 ng / mL, and the ULQ was 10,000 ng / mL.

[0091] Calculation of pharmacokinetic parameters: Test article concentration data was uploaded into the Thermo Scientific™ Watson LIMS™ system, which used non-compartmental analysis to calculate the Area Under the Curve (AUC) for both the IV and PO groups, as well as the Mean Residence Time (MRT) from the IV group.

[0092] Bioavailability (F%) was calculated as follows: F%=(AUC PO ×Dose IV ) / (AUC IV ×Dose PO ) x 100.

[0093] IV Clearance (CL IV ) was calculated as follows: CL=Dose / AUC IV

[0094] The volume of distribution at steady state (Vd,ss) was calculated as follows: Vd,ss=CL * MRT

[0095] The pharmacokinetic parameters determined from the above assays are shown in Table 4.

[0096] [Table 4]

[0097] Hepatocyte assays demonstrate that both the compound of Example 1 and Compound A have low turnover, but surprisingly, in vivo studies in mice showed that the compounds have different pharmacokinetic profiles, with the compound of Example 1 exhibiting lower clearance and higher oral bioavailability. These data suggest that, despite similarly low intrinsic clearance, the deuterated compounds of the present disclosure may allow for lower dose amounts and / or frequency while still achieving therapeutic levels of target binding compared to Compound A.

Claims

1. A compound of the formula: 【Chemistry 1】 wherein R １ but the following: 【Chemistry 2】 or a pharma- ceutically acceptable salt thereof.

2. A compound of the formula: 【Chemistry 3】 2. The compound of claim 1, wherein:

3. A compound of the formula: 【Chemistry 4】 2. The compound of claim 1, wherein:

4. A compound of the formula: 【Chemistry 5】

5. A compound of the formula: 【Chemistry 6】

6. 2. The compound of claim 1, or a pharma- ceutically acceptable salt thereof, wherein each position designated as D has a deuterium enrichment of at least 50%.

7. 2. The compound of claim 1, or a pharma- ceutically acceptable salt thereof, wherein each position designated as D has a deuterium enrichment of at least 80%.

8. 2. The compound of claim 1, or a pharma- ceutically acceptable salt thereof, wherein each position designated as D has a deuterium enrichment of at least 90%.

9. 2. The compound of claim 1, or a pharma- ceutically acceptable salt thereof, wherein each position designated as D has a deuterium enrichment of at least 95%.

10. 2. The compound of claim 1, or a pharma- ceutically acceptable salt thereof, wherein each position designated as D has a deuterium enrichment of at least 99%.

11. A compound of the formula: 【Chemistry 7】 wherein each position designated as D has a deuterium enrichment of at least 50%.

12. 12. The compound of claim 11, wherein each position designated as D has a deuterium enrichment of at least 80%.

13. 12. The compound of claim 11, wherein each position designated as D has a deuterium enrichment of at least 90%.

14. 12. The compound of claim 11, wherein each position designated as D has a deuterium enrichment of at least 95%.

15. 12. The compound of claim 11, wherein each position designated as D has a deuterium enrichment of at least 99%.

16. A compound of the formula: 【Chemistry 8】 wherein each position designated as D has a deuterium enrichment of at least 50%.

17. 17. The compound of claim 16, wherein each position designated as D has a deuterium enrichment of at least 80%.

18. 17. The compound of claim 16, wherein each position designated as D has a deuterium enrichment of at least 90%.

19. 17. The compound of claim 16, wherein each position designated as D has a deuterium enrichment of at least 95%.

20. 17. The compound of claim 16, wherein each position designated as D has a deuterium enrichment of at least 99%.

21. A therapeutic agent for pain, comprising the compound according to any one of claims 1 to 20, or a pharma- ceutically acceptable salt thereof.

22. A therapeutic agent for chronic pain, comprising the compound according to any one of claims 1 to 20, or a pharma- ceutically acceptable salt thereof.

23. A therapeutic agent for chronic lower back pain, comprising the compound according to any one of claims 1 to 20, or a pharma- ceutically acceptable salt thereof.

24. A therapeutic agent for diabetic peripheral neuropathy pain, comprising the compound according to any one of claims 1 to 20, or a pharma- ceutically acceptable salt thereof.

25. A therapeutic agent for osteoarthritis pain, comprising a compound according to any one of claims 1 to 20, or a pharma- ceutically acceptable salt thereof.

26. 21. Use of a compound according to any one of claims 1 to 20, or a pharma- ceutically acceptable salt thereof, for the manufacture of a medicament for treating pain.

27. 21. Use of a compound according to any one of claims 1 to 20, or a pharma- ceutically acceptable salt thereof, for the manufacture of a medicament for treating chronic pain.

28. 21. Use of a compound according to any one of claims 1 to 20, or a pharma- ceutically acceptable salt thereof, for the manufacture of a medicament for treating chronic lower back pain.

29. 21. Use of a compound according to any one of claims 1 to 20, or a pharma- ceutically acceptable salt thereof, for the manufacture of a medicament for treating diabetic peripheral neuropathic pain.

30. 21. Use of a compound according to any one of claims 1 to 20, or a pharma- ceutically acceptable salt thereof, for the manufacture of a medicament for treating osteoarthritis pain.

31. 21. A pharmaceutical composition comprising a compound according to any one of claims 1 to 20, or a pharma- ceutically acceptable salt thereof, together with one or more pharma- ceutically acceptable carriers, diluents, or excipients.

32. A pharmaceutical composition comprising a compound according to any one of claims 1 to 20, together with one or more pharma- ceutically acceptable carriers, diluents or excipients.

33. 21. A process for preparing a pharmaceutical composition, comprising mixing a compound according to any one of claims 1 to 20, or a pharma- ceutically acceptable salt thereof, with one or more pharma- ceutically acceptable carriers, diluents or excipients.

34. 21. A process for preparing a pharmaceutical composition, comprising mixing a compound according to any one of claims 1 to 20 with one or more pharma- ceutically acceptable carriers, diluents or excipients.

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