Patent Grant
9469647
The present invention relates to acid addition salts and salt crystals of (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one, composition comprising the same and the method of making and using such salts and salt crystals.
The compound (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one is disclosed in WO 2009/075784 (U.S. Pub. No. 2010/0273754). This compound has been found to be a potent and selective phosphodiesterase 1 (PDE 1) inhibitor useful for the treatment or prophylaxis of disorders characterized by low levels of cAMP and/or cGMP in cells expressing PDE1, and/or reduced dopamine D1 receptor signaling activity (e.g., Parkinson's disease, Tourette's Syndrome, Autism, fragile X syndrome, ADHD, restless leg syndrome, depression, cognitive impairment of schizophrenia, narcolepsy); and/or any disease or condition that may be ameliorated by the enhancement of progesterone signaling. This list of disorders is exemplary and not intended to be exhaustive.
The publication WO 2009/075784 discloses (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one in free base form and generally in pharmaceutically acceptable salt form, but no specific salt was shown to have particular stability or desired properties. Because many pharmaceutical compounds can exist in different physical forms (e.g., liquid or solid in different crystalline, amorphous, polymorphous, hydrate or solvate forms) which can vary the stability, solubility, bioavailability or pharmacokinetics (absorption, distribution, metabolism, excretion or the like) and/or bioequivalency of a drug, it is of critical importance in the pharmaceutical development to identify a pharmaceutical compound of optimal physical form (e.g., free base or salt in solid, liquid, crystalline, hydrate, solvate, amorphous or polymorphous forms).
Using twelve acids and eight different solvent systems, our scientists have surprisingly found that (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one forms stable acid addition salts and in certain instances, forms crystallinic acid addition salts with particular acids. These salts and salt crystals are especially advantageous in the preparation of galenic formulations of various and diverse kind. Therefore, in the first aspect, the invention provides the following:
It has also been surprisingly found that particular Salts of the Present Invention are in crystalline form, and therefore are preferred for galenic and/or therapeutic use. Therefore, in the second embodiment, the invention provides the following:
The invention also provides a process for the production of Salt of the Invention, e.g., selected from the group consisting of fumarate, hydrochloric, (1-hydrox-2)-naphthoate, benzosulfonate, phosphate, mesylate, tartrate, sulphate and hydrobromate salt crystals, comprising the steps of reacting (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one with an acid, e.g., selected from the group consisting of fumaric acid, hydrochloric acid, (1-hydroxy-2)-naphthoic acid, benzenesulfonic acid, phosphoric acid, methanesulphonic acid, tartaric acid, sulphuric acid and hydrobromic acid in a solvent and isolating the salt obtained. Preferably, the salt is a phosphate salt and the acid is phosphoric acid, e.g., aqueous phosphoric acid, phosphoric acid hydrate or phosphoric acid crystal in a solvent. In a particular embodiment, the invention provides the following:
In the third aspect, the invention provides the following:
As use herein, the term “crystal” or “crystals” or “crystalline” or “crystallinic” refers to any solid that has a short or long range order of the molecules, atoms or ions in a fixed lattice arrangement. Salt Crystals of the Present Invention may be in a single crystal form. Therefore, the Salt Crystals of the Present Invention may be in a triclinic, monoclinic, orthorhombic, tetragonal, rhombohedral, hexagonal or cubic crystal form or mixtures thereof. In particular, the Salt Crystals of the Present Invention are in dry crystalline form. In another embodiment, the Salt Crystals of the Present Invention are in needle form. In still another embodiment, the Salt Crystals of the Present Invention are in plate-like form. In a particular embodiment, the Salt Crystals of the Present Invention are substantially free of other forms, e.g., free of amorphous or other crystal forms.
The term “substantially free” of other crystal forms refer to less than about 10 wt. %, preferably less than about 5 wt. %, more preferably less than about 2 wt. %, still preferably less than about 1 wt. %, still preferably less than about about 0.1%, most preferably less than about 0.01 wt. % of other forms or other crystal forms, e.g., amorphous or other crystal forms.
The term “predominantly” or “substantially entirely in a single form” refers to less than about 10 wt. %, preferably less than about 5 wt. %, more preferably less than about 2 wt. %, still preferably less than about 1 wt. %, still preferably less than about about 0.1%, most preferably less than about 0.01 wt. % of other crystal forms, e.g., amorphous or other crystal forms.
In particular embodiment, the Salt Crystals of the invention may contain trace amounts of solvent, e.g., in solvate form, or trace amounts of water, e.g., in hydrate form. Preferably, the Salt Crystals of the invention are in non-solvate form. Still preferably, the Salt Crystals of the invention are in non-solvate and non-hydrate form.
The Salt Crystals of the invention may have a free base to acid ratio of 1 to 1, 1 to 0.5 or 1 to >1, e.g., 1 to 1.3 or 1 to 2, etc. For example, the phosphate salt crystal of the invention may comprise 1 molar equivalent of the free base to 1 molar equivalent of the phosphoric acid. Preferably, the phosphate salt crystal of the invention comprises 1 molar equivalent of the free base to 1 molar equivalent of the phosphoric acid Wherein the acid is a di-acid, such as fumaric acid or tartaric acid, the ratio of free base to acid may be 1 molar equivalent of free base to 0.5 equivalent of the di-acid, e.g., to form a hemi-fumarate or hemi-tartrate salt.
The term “solvate” refers to crystalline solid adducts containing either stoichiometric or nonstoichiometric amounts of a solvent incorporated within the crystal structure. Therefore, the term “non-solvate” form herein refers to salt crystals that are free or substantially free of solvent molecules within the crystal structures of the invention. Similarly, the term “non-hydrate” form herein refers to salt crystals that are free or substantially free of water molecules within the crystal structures of the invention.
The term “amorphous” form refers to solids of disordered arrangements of molecules and do not possess a distinguishable crystal lattice.
The crystallinity or the morphology of the Salt Crystals of the Present Invention may be determined by a number of methods, including, but not limited to single crystal X-ray diffraction, X-ray powder diffraction, polarizing optical microscopy, thermal microscopy, differential scanning Calorimetry (DSC), thermogravimetric analysis (TGA), infrared adsorption spectroscopy and Raman spectroscopy. Characterization of solvates or hydrates or lack thereof may also be determined by DSC and/or TGA.
It is to be understood that X-ray powder diffraction pattern or the differential scanning calorimetry pattern of a given sample may vary a little (standard deviation) depending on the instrument used, the time and temperature of the sample when measured and standard experimental errors. Therefore, the temperature or the 2-theta values, d-spacing values, heights and relative intensity of the peaks as setforth herein in Tables 1-3 or in
The term “about” in front of a numerical value refers to the numerical value itself ±20%, ±15%, ±10%, preferably ±5%, preferably ±3%, preferably ±2%, preferably ±1% of that value. When referencing temperature, the term about refers to the temperature value itself ±10° C., preferably ±5° C., preferably ±3° C. of the reference temperature. In another example, when referencing 2-theta angle values, the term “about” refers to the numerical 2-theta angle value itself ±0.2 degrees of the reference 2-theta angle value. In still another example, when referencing d-spacing values, the term “about” refers to the numerical 2-theta angle value itself ±0.2 Å of of the reference d-spacing value.
The Salt Crystals of the invention are selective PDE1 inhibitors. Therefore, the Salt Crystals of the invention are useful for the treatment of PDE1 related disorders as setforth in e.g., WO 2009/075784, WO 2010/132127, WO 2006/133261 and WO 2011/153129, the contents of each of which are incorporated by reference in their entirety.
The term “patient” includes human and non-human. In one embodiment, the patient is a human. In another embodiment, the patient is a non-human.
A stock solution of (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one in methanol (80 mg/ml in MeOH) is prepared. The mixture of 3.301 ml of the stock solution, 0.36 ml water and 22.5 μl (˜50 mg) methanesulfonic acid is stirred at room temperature, resulting a clear solution. The mixture/solution is subjected to temperature cycling (40° C./RT, each for 4 h) for overnight (no solid material crashed out). 14 ml Diethyl Ether (anti-solvent) is added, white solid materials is produced gradually and isolated.
X-Ray Powder Diffraction: The XRPD of the mesylate salt crystals is obtained as described or similarly described herein. Approximately 2 mg of the sample is gently compressed on the XRPD zero back ground single obliquely cut silica sample holder. The sample is then loaded into a Philips X-Pert MPD diffractometer and analysed using the following experimental conditions.
Method 1
Tube anode: Cu
Generator tension: 40 kV
Tube current: 40 mA
Wavelength alpha1: 1.5406 A
Wavelength alpha2: 1.5444 A
Start angle [2 theta]: 5.000
End angle [2 theta]: 50.003
Step size: 0.0167113
Time per step: 30.480 seconds
No of step: 2693
Total tine (h:m:s): 00:11:19
For an analysis of XRPD, some material is checked using Method 2 (see below). If S/N (signal to noise ratio) is not good enough then XRPD was repeated using Method 1.
Method 2
Start angle [2 theta]: 5.000
End angle [2 theta]: 49.992
Step size: 0.016
Time per step2.00 seconds
No of step: 2812
Total tine (h:m:s): 00:1:33
The XRPD pattern of the mesylate Salt Crystals is depicted in
Thermogravimetic Analysis (TGA) & Differential Thermal Analysis (DTA) of the mesylate salt crystal of Example 1 is obtained as described or similarly described herein and the DTA is depicted in
180 mg of (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one[0.354 mmole] is dissolved in MeOH (2 mL) with heating. Fumaric acid (41 mg) [0.354 mmole] is added to the hot solution. The solution is left at room temperature for 45 minutes for crystallization. The solids are isolated by vacuum filtration. The solids are dried in an oven at 50° C. for 24 hours.
The XRPD of the fumarate salt crystals is obtained as described or similarly described herein. Approximately 20 mg of sample is gently compressed on the XRPD zero back ground single obliquely cut silica sample holder. The sample was then loaded into a Philips X-Pert PRO diffractometer and analysed using the following experimental conditions.
Tube anode: Cu
Generator tension: 40 kV
Tube current: 40 mA
Wavelength alpha1: 1.5406 A
Wavelength alpha2: 1.5444 A
Start angle [2 theta]: 4
End angle [2 theta]: 40
Time per step: 2.5 seconds
Scan step size: 0.016
The XRPD pattern of the fumarate Salt Crystals is depicted in
Differential Scanning Calorimetry (DSC) thermograph of the fumarate Salt Crystals is obtained as described or similarly described herein and the DSC is depicted in
The mono-phosphate salt crystals of the invention may be prepared as described or similarly described herein. A 3 L three-neck round bottom flask in a heating mantle with a mechanical stirrer, thermocouple, nitrogen inlet, addition funnel, reflux condenser and a drying tube is prepared. (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one free base (147 g, SM) and acetonitrile (1470 mL, 10 mL/g SM) is charged to the flask and stirred. The resulting solution is heated to 40-45° C. A solution of 85 wt. % phosphoric acid (33.4 g, 0.227 g/g SM) in acetonitrile (265 mL, 1.8 mL/g SM) is slowly added over a minimum of 1 hour, maintaining the reaction mixture at 40-45° C. The addition funnel is rinsed with acetonitrile (29 mL, 0.2 mL/g SM). Heating is removed and the reaction mixture is stirred under nitrogen at ambient temperature over 12-24 hours. The solids are filtered and rinsed with acetonitrile (2×294 mL; 2×2 mL/g SM). The product is dried in a vacuum oven at 70-75° C. with nitrogen bleed over a minimum of 12 hours to yield a constant weight.
The XRPD of the mono-phosphate salt crystals is obtained as described or similarly described herein. The result is depicted in
Tube anode: Cu
Generator tension: 40 kV
Tube current: 40 mA
Wavelength alpha1: 1.5406 A
Wavelength alpha2: 1.5444 A
Start angle [2 theta]: 4
End angle [2 theta]: 40
Time per step: 2.5 seconds
Scan step size: 0.016
The XRPD pattern of the mono-phosphate Salt Crystals is depicted in
Thermogravimetic Analysis (TGA) & Differential Thermal Analysis (DTA) of the mono-phosphate salt crystals is obtained as described or similarly described herein and the DTA is depicted in
Differential Scanning Calorimetry (DSC) thermograph of the mono-phosphate Salt Crystals is obtained as described or similarly described herein and the DSC is depicted in
The mono-phosphate Salt Crystals are particularly stable, has good solubility, low hygroscopicity, high melting point, has plate-like morphology and are non-solvate, none-hydrate, all of which are desirable properties for galenic formulation.
Alternative to the process described above, the monophosphate salt crystals may also be prepared by dissolving the (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one free base in non-solvate or solvate (e.g., mono-ethanol, methanol, n-propanol, isopropanol, n-butanol solvate or non-solvate) crystal form in a suitable solvent (e.g., in acetonitrile at 50° C. or in acetone at 38° C.). Active charcoal is added and the mixture is stirred at the same temperature for 0.5 h. After removing the active charcoal by filtration, the fitrate is warmed to 50° C. (if acetonitrile is used) or 32-39° C. (if acetone is used). An equimolar amount of 85 wt. % phosphoric acid in a suitable solvent (e.g., acetonitrile or acetone) is added. After addition of water, the mixture is stirred at 20-70° C., e.g., 50° C. or 40° C. The mono-phosphate crystals are then isolated by filtration.
The free base crystals may be prepared by (1) stirring (6aR,9aS)-3-chloro-2-(4-(6-fluoropyridin-2-yl)benzyl)-5-methyl-5,6a,7,8,9,9a-hexahydrocyclopenta[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one in a suitable solvent (e.g., combination of DMAc and xylene) in the presence of base (e.g. potassium carbonate), aniline, palladium catalyst (e.g., Pd(OAc)2) and ligand (e.g., xantphos), then separating organic layer; (2) adding the solvent corresponding to objective solvate form (e.g., adding ethanol to form an ethanol solvate) to the organic layer obtained in the step 1). n-Heptane may be added at 70° C. and then cooled to 5° C. and stirred. The crystals may be separated by filtration. Preferably, step (1) is carried out under nitrogen atmosphere and the separated organic layer is washed with a suitable solution (DMAc or xylene) and then treated with charcoal to remove residual palladium catalyst. The free base crystal may also be prepared by using seed crystals of (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one in non-solvate form.
The method of making the Compound (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one is generally described in WO 2009/075784, the contents of which are incorporated by reference in their entirety. This compound can also be prepared as summarized or similarly summarized in the following reaction scheme.
In particular, (6aR,9aS)-3-chloro-2-(4-(6-fluoropyridin-2-yl)benzyl)-5-methyl-5,6a,7,8,9,9a-hexahydrocyclopenta[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one may be prepared as described or similarly described below.
The mixture of Na2CO3 (121 g), water (500 mL), THF (650 mL), PdCl2(PPh3)2 (997 mg), 2-bromo-6-fluoropyridine (100 g) and 4-(hydroxymethyl)phenylboronic acid (90.7 g) is stirred at 65° C. for 4 h under the nitrogen atmosphere. After cooling to room temperature, THF (200 mL) is added. The organic layer is separated and washed with 5% NaCl solution twice. The organic layer is concentrated to 400 mL. After the addition of toluene (100 mL), heptane (500 mL) is added at 55° C. The mixture is cooled to room temperature. The crystals are isolated by filtration, washed with the mixture of toluene (100 mL) and heptane (100 mL) and dried to give (4-(6-fluoropyridin-2-yl)phenyl)methanol (103 g). 1H NMR (500 MHz, CDCl3) δ 1.71-1.78 (m, 1H), 4.74-4.79 (m, 2H), 6.84-6.88 (m, 1H), 7.44-7.50 (m, 2H), 7.61-7.65 (m, 1H), 7.80-7.88 (m, 1H), 7.98-8.04 (m, 2H).
The solution of thionylchloride (43.1 mL) in AcOEt (200 mL) is added to the mixture of (4-(6-fluoropyridin-2-yl)phenyl)methanol (100 g), DMF (10 mL) and AcOEt (600 mL) at room temperature. The mixture is stirred at room temperature for 1 h. After cooling to 10° C., 15% Na2CO3 solution is added. The organic layer is separated and washed with water (500 mL) and 5% NaCl solution (500 mL) twice. The organic layer is concentrated to 500 mL. After the addition of EtOH (500 mL), the mixture is concentrated to 500 mL. After addition of EtOH (500 mL), the mixture is concentrated to 500 mL. After the addition of EtOH (500 mL), the mixture is concentrated to 500 mL. After addition of EtOH (200 mL), water (700 mL) is added at 40° C. The mixture is stirred at room temperature. The crystals are isolated by filtration and dried to give 2-(4-(chloromethyl)phenyl)-6-fluoropyridine (89.5 g). 1H NMR (500 MHz, CDCl3) δ 4.64 (s, 2H), 6.86-6.90 (m, 1H), 7.47-7.52 (m, 2H), 7.60-7.65 (m, 1H), 7.82-7.88 (m, 1H), 7.98-8.03 (m, 2H).
The mixture of 6-chloro-3-methyluracil (100 g), p-methoxybenzylchloride (107 g), K2CO3 (86.1 g) and DMAc (600 mL) is stirred at 75° C. for 4 h. Water (400 mL) is added at 45° C. and the mixture is cooled to room temperature. Water (800 mL) is added and the mixture is stirred at room temperature. The crystals are isolated by filtration, washed with the mixture of DMAc and water (1:2, 200 mL) and dried to give 6-chloro-1-(4-methoxybenzyl)-3-methylpyrimidine-2,4(1H,3H)-dione (167 g). 1H NMR (500 MHz, CDCl3) δ 3.35 (s, 3H), 3.80 (s, 3H), 5.21 (s, 2H), 5.93 (s, 1H), 6.85-6.89 (m, 2H), 7.26-7.32 (m, 2H).
The mixture of 6-chloro-1-(4-methoxybenzyl)-3-methylpyrimidine-2,4(1H,3H)-dione (165 g), IPA (990 mL), water (124 mL) and hydrazine hydrate (62.9 mL) is stirred at room temperature for 1 h. The mixture is warmed to 60° C. and stirred at the same temperature for 4 h. Isopropyl acetate (1485 mL) is added at 45° C. and the mixture is stirred at the same temperature for 0.5 h. The mixture is cooled at 10° C. and stirred for 1 h. The crystals are isolated by filtration, washed with the mixture of IPA and isopropyl acetate (1:2, 330 mL) and dried to give 6-hydrazinyl-1-(4-methoxybenzyl)-3-methylpyrimidine-2,4(1H,3H)-dione (153 g). 1H NMR (500 MHz, DMSO-d6) δ 3.12 (s, 3H), 3.71 (s, 3H), 4.36 (s, 2H), 5.01 (s, 2H), 5.14 (s, 1H), 6.87-6.89 (m, 2H), 7.12-7.17 (m, 2H), 8.04 (s, 1H).
To the mixture of DMF (725 mL) and 6-hydrazinyl-1-(4-methoxybenzyl)-3-methylpyrimidine-2,4(1H,3H)-dione (145 g) is added POCl3 (58.5 mL) at 5° C. The mixture is stirred at room temperature for 1 h. Water (725 mL) is added at 50° C. and the mixture is stirred at room temperature for 1 h. The crystals are isolated by filtration, washed with the mixture of DMF and water (1:1, 290 mL) and dried to give 7-(4-methoxybenzyl)-5-methyl-2H-pyrazolo[3,4-d]pyrimidine-4,6(5H,7H)-dione (145 g). 1H NMR (500 MHz, DMSO-d6) δ 3.23 (s, 3H), 3.71 (s, 3H), 5.05 (s, 2H), 6.82-6.90 (m, 2H), 7.28-7.36 (m, 2H), 8.48 (s, 1H), 13.51 (br, 1H).
The mixture of 2-(4-(chloromethyl)phenyl)-6-fluoropyridine (100 g), 7-(4-methoxybenzyl)-5-methyl-2H-pyrazolo[3,4-d]pyrimidine-4,6(5H,7H)-dione (129 g), K2CO3 (62.3 g) and DMAc (1500 mL) is stirred at 45° C. for 5 h. Water (1500 mL) is added at 40° C. and the mixture is stirred at room temperature for 1 h. The crystals are isolated by filtration, washed with the mixture of DMAc and water (1:1, 500 mL) and dried to give 2-(4-(6-fluoropyridin-2-yl)benzyl)-7-(4-methoxybenzyl)-5-methyl-2H-pyrazolo[3,4-d]pyrimidine-4,6(5H,7H)-dione (207 g). 1H NMR (500 MHz, DMSO-d6) δ 3.21 (s, 3H), 3.66 (s, 3H), 4.98 (s, 2H), 5.45 (s, 2H), 6.77-6.82 (m, 2H), 7.13-7.16 (m, 1H), 7.25-7.30 (m, 2H), 7.41-7.44 (m, 2H), 7.92-7.96 (m, 1H), 8.04-8.11 (m, 3H), 8.68 (s, 1H).
The mixture of 2-(4-(6-fluoropyridin-2-yl)benzyl)-7-(4-methoxybenzyl)-5-methyl-2H-pyrazolo[3,4-d]pyrimidine-4,6(5H,7H)-dione (105 g), CF3COOH (300 mL) and CF3SO3H (100 g) is stirred at room temperature for 10 h. Acetonitrile (1000 mL) is added. The mixture is added to the mixture of 25% NH3 (1000 mL) and acetonitrile (500 mL) at 10° C. The mixture is stirred at room temperature for 1 h. The crystals are isolated by filtration, washed with the mixture of acetonitrile and water (1:1, 500 mL) and dried to give the crude product. The mixture of the crude product and AcOEt (1200 mL) is stirred at room temperature for 1 h. The crystals are isolated by filtration, washed with AcOEt (250 mL) and dried to give 2-(4-(6-fluoropyridin-2-yl)benzyl)-5-methyl-2H-pyrazolo[3,4-d]pyrimidine-4,6(5H,7H)-dione (75.3 g). 1H NMR (500 MHz, DMSO-d6) δ 3.16 (s, 3H), 3.50-4.00 (br, 1H), 5.40 (s, 2H), 7.13-7.16 (m, 1H), 7.41-7.44 (m, 2H), 7.91-7.94 (m, 1H), 8.04-8.10 (m, 3H), 8.60 (s, 1H).
The mixture of BOP reagent (126 g), 2-(4-(6-fluoropyridin-2-yl)benzyl)-5-methyl-2H-pyrazolo[3,4-d]pyrimidine-4,6(5H,7H)-dione (80 g), DBU (136 mL) and THF (1120 mL) is stirred at room temperature for 1 h. (1R,2R)-2-Aminocyclopentanol hydrochloride (37.6 g) and THF (80 mL) are added and the mixture is stirred at room temperature for 5 h. After the addition of 5% NaCl (400 mL) and AcOEt (800 mL), the organic layer is separated. The organic layer is washed with 10% NaCl (400 mL), 1M HCl 15% NaCl (400 mL), 5% NaCl (400 mL), 5% NaHCO3 (400 mL) and 5% NaCl (400 mL) successively. After treatment with active charcoal, the organic layer is concentrated to 400 mL. After the addition of acetonitrile (800 mL), the mixture is concentrated to 400 mL. After the addition of acetonitrile (800 mL), seed crystals are added at 40° C. The mixture is concentrated to 400 mL. Water (800 mL) is added at room temperature and the mixture is stirred for 2 h. The crystals are isolated by filtration, washed with the mixture of acetonitrile and water (1:2, 400 mL) and dried to give 2-(4-(6-fluoropyridin-2-yl)benzyl)-6-(((1R,2R)-2-hydroxycyclopentyl)amino)-5-methyl-2H-pyrazolo[3,4-d]pyrimidin-4(5H)-one (81.7 g). 1H NMR (500 MHz, CDCl3) δ 1.47-1.59 (m, 1H), 1.68-1.93 (m, 3H), 2.02-2.12 (m, 1H), 2.24-2.34 (m, 1H), 3.42 (s, 3H), 3.98-4.12 (m, 2H), 4.68-4.70 (m, 1H), 5.37 (s, 2H), 6.86-6.90 (m, 1H), 7.36-7.42 (m, 2H), 7.58-7.63 (m, 1H), 7.81-7.88 (m, 1H), 7.89 (s, 1H), 7.97-8.01 (m, 2H).
The mixture of 2-(4-(6-fluoropyridin-2-yl)benzyl)-6-(((1R,2R)-2-hydroxycyclopentyl)amino)-5-methyl-2H-pyrazolo[3,4-d]pyrimidin-4(5H)-one (80 g), p-toluenesulfonylchloride (38.6 g), Et3N (28.2 mL), N,N-dimethylaminopyridine (24.7 g) and THF (800 mL) is stirred at 50° C. for 10 h. To the mixture is added 8M NaOH (11.5 mL) at room temperature and the mixture is stirred for 2 h. After the addition of 5% NaCl (400 mL) and AcOEt (800 mL), the organic layer is separated. The organic layer is washed with 5% NaCl (400 mL) twice. The organic layer is concentrated to 240 mL. After the addition of MeOH (800 mL), the mixture is concentrated to 240 mL. After the addition of MeOH (800 mL), the mixture is concentrated to 240 mL. After the addition of MeOH (160 mL), the mixture is stirred at room temperature for 1 h and at 0° C. for 1 h. The crystals are isolated by filtration, washed with cold MeOH (160 mL) and dried to give (6aR,9aS)-2-(4-(6-fluoropyridin-2-yl)benzyl)-5-methyl-5,6a,7,8,9,9a-hexahydrocyclopenta[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one (55.7 g). 1H NMR (500 MHz, CDCl3) δ 1.39-1.54 (m, 1H), 1.58-1.81 (m, 3H), 1.81-1.92 (m, 1H), 2.12-2.22 (m, 1H), 3.28 (s, 3H), 4.61-4.70 (m, 2H), 5.20 (s, 2H), 6.79-6.85 (m, 1H), 7.25-7.32 (m, 2H), 7.53-7.58 (m, 1H), 7.68 (s, 1H), 7.75-7.83 (m, 1H), 7.92-7.98 (m, 2H).
The mixture of (6aR,9aS)-2-(4-(6-fluoropyridin-2-yl)benzyl)-5-methyl-5,6a,7,8,9,9a-hexahydrocyclopenta[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one (50 g) and toluene (1000 mL) is concentrated to 750 mL under the nitrogen atmosphere. Toluene (250 mL) and NCS (24 g) is added. To the mixture is added LiHMDS (1M THF solution, 204 mL) at 0° C. and the mixture is stirred for 0.5 h. To the mixture is added 20% NH4Cl (50 mL) at 5° C. The mixture is concentrated to 250 mL. After the addition of EtOH (250 mL), the mixture is concentrated to 150 mL. After the addition of EtOH (250 mL), the mixture is concentrated to 200 mL. After the addition of EtOH (200 mL), the mixture is warmed to 50° C. Water (300 mL) is added and the mixture is stirred at 50° C. for 0.5 h. After stirring at room temperature for 1 h, the crystals are isolated by filtration, washed with the mixture of EtOH and water (1:1, 150 mL) and dried to give (6aR,9aS)-3-chloro-2-(4-(6-fluoropyridin-2-yl)benzyl)-5-methyl-5,6a,7,8,9,9a-hexahydrocyclopenta[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one (51.1 g). 1H NMR (500 MHz, CDCl3) δ 1.46-1.61 (m, 1H), 1.67-1.90 (m, 3H), 1.92-2.00 (m, 1H), 2.19-2.27 (m, 1H), 3.37 (s, 3H), 4.66-4.77 (m, 2H), 5.34 (s, 2H), 6.87-6.93 (m, 1H), 7.35-7.41 (m, 2H), 7.59-7.65 (m, 1H), 7.82-7.91 (m, 1H), 7.97-8.05 (m, 2H).
60 mg of the (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one free base [0.118 mmole] is dissolved in Acetone (3 mL). L-tartaric acid (17.7 mg) [0.118 mmole] is added to the solution. The solution is left at room temperature for 30 minutes for crystallization. The solids are isolated by vacuum filtration, then the solids are air dried for 20 minutes. The XRPD of the L-tartrate salt crystals is obtained as described or similarly described in Example 2. The result is depicted in
The (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one mono-phosphate salt crystals are assessed for its aqueous solubility at lower pH. The (amorphous) free base is also tested for reference at a limited range of pH.
Phosphate (buffer) solutions are made at 50 mM concentration and the pH is adjusted to pH 2, 3, 4, 5 or 6.8 using either 3M phosphoric acid (lower pH) or 3M NaOH (higher pH). 0.1N HCl is also used, pH is measured as 1.2.
20 mg of the (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one mono-phosphate salt crystals or free base is weighed into a glass vial, and 2 ml of the relevant aqueous media is added. The vials are shaken. After 1 hr, a sample (˜1 ml) is removed via syringe, and filtered through a syringe filter (0.2 micron) into an HPLC vial. After shaking the suspensions for 16 hours, a second sample is taken. All samples are then diluted with the HPLC diluent by a factor of 1000 (except the pH 6.8 samples which are diluted ×10), and re-analysed by HPLC. In cases where the entire solid dissolved, the 2 ml solution is added to another 20 mg salt or free base.
The solubility study shows that the mono-phosphate salt crystals have similar solubility to the amorphous free base at low pH (pH 1.2 and 2) in the range of 16->20 mg/ml. The mono-phosphate salt crystals show better solubility than the amorphous free base at pH 3 and gives solubility of up to 7.7 mg/ml at pH 4. The results are summarized below:
The rate of dissolution is an important factor in the bioavailability of an active pharmaceutical ingredient (API). This is commonly tested using standard conditions e.g. USP 2 dissolution testing. The pH of the aqueous media used can be correlated with the pH of the stomach (low pH −1-2) and the intestines (intermediate acidic pH −4-6). Therefore pH 1 (0.1 M HCl) and a citrate buffer at pH 4.5 (0.2M) are used for the dissolution testing.
The (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one mono-phosphate salt crystals are weighed (×4) into size 0 white gelatine capsules at 119 mg per capsule (equivalent to 100 mg API). The (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo-[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one is also weighed (×2) into white gelatine capsules at 100 mg per capsule. These capsules are then dissolved using the standard set up of the USP 2 dissolution equipment i.e., in 1000 mL of the relevant aqueous media, stirrers set at 50 rpm, capsules placed in metal coils to weigh them down, media equilibrated with the water bath set at 37″C. Analytical samples are removed via canula, with an initial filter on the canula and secondary filtering through 0.2 micron syringe filters. The samples are then analysed without dilution by HPLC for API content. Calibration for HPLC is run using both the free base API and the phosphate salt.
This study shows that the mono-phosphate salt crystals and the amorphous free base at low pH (pH 1) have good solubility. At about 0.1 mg/mL (API equivalent), full dissolution is observed after approximately 15 minutes. Both the mono-phosphate salt crystals dissolution study show better dissolution rates than the free base. The dissolution profiles of the mono-phosphate salt crystals and the free base at pH 1 are depicted in
The mono-phosphate salt of (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one is administered to dogs at a dose of 40 mg/kg in gelatin capsules or via oral gavage in a vehicle formulation of HCl-Citrate, pH 3.5, 0.5% methylcellulose in water. These data are compared to another study of the free base study in which the (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one free base is administered via oral gavage to dogs at 40 mg/kg in a vehicle containing HCl-Citrate, pH 3.5, 0.5% methylcellulose in water. The analysis of drug concentration in plasma samples collected is analyzed.
The pharmacokinetic (PK) parameters are determined from the plasma concentration versus time data by non-compartmental methods with uniform weighting (PK solutions 2.0™, Summit Research Services, Montrose, Colo.). The maximum observed concentration (Cmax) and the time of the maximum observed concentration (tmax) are obtained from the bioanalytical raw data. The area-under-the-plasma concentration-time curve from time zero to the time of the last measurable sample (AUC_) is calculated by the trapezoidal rule. The plasma pharmacokinetic (PK) profile of the free base and the phosphate salt crystal in 40 mg/kg dosage is provided in Tables 5 and 6 below.
In a single rising dose clinical study involving 55 active subjects (15 placebo) with 11 active:3 placebo for each dose level of 10, 25, 75, 150, 300 mg, the mono-phosphate salt crystals of (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one is dissolved in water, and this aqueous solution is orally administered. The pharmacokinetic profile is setforth below in Table 7.
Comparing Table 5 and Table 6 with Table 7, the results indicate a substantially higher plasma level in human at the 25 and 75 mg doses in Cmax, and in AUC compared to dogs.
The hydrochloride, (1-Hydroxy-2-) naphthoate and benzolsulfonate salt of the Invention may be prepared as described or similarly described below: 8 mg (6aR,9aS)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylamino)-2-((4-(6-fluoropyridin-2-yl)phenyl)methyl)-cyclopent[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyrimidin-4(2H)-one in either 20:1 acetone:water, 90:10 methanol:water or isopropyl alcohol is reacted with 1 equivalent of the acid. Anti-solvent addition (diethyl ether as anti-solvent) is then used to help precipitation of solid materials. The salts may be isolated from the following system:
hydrochloride—(in Acetone/H2O 20/1; isopropyl alcohol and MeOH/H2O 90/10 after anti-solvent addition);
(1-hydroxy-2) Naphthoate—(in isopropyl alcohol and MeOH/H2O 90/10 after anti-solvent addition);
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