WO2006091980A1 - Process of purifying tadalafil - Google Patents
Process of purifying tadalafil Download PDFInfo
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- WO2006091980A1 WO2006091980A1 PCT/US2006/007338 US2006007338W WO2006091980A1 WO 2006091980 A1 WO2006091980 A1 WO 2006091980A1 US 2006007338 W US2006007338 W US 2006007338W WO 2006091980 A1 WO2006091980 A1 WO 2006091980A1
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- Prior art keywords
- tadalafil
- solution
- solvent
- crude
- purified
- Prior art date
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- 229960000835 tadalafil Drugs 0.000 title claims abstract description 87
- 238000000034 method Methods 0.000 title claims abstract description 44
- IEHKWSGCTWLXFU-IIBYNOLFSA-N tadalafil Chemical compound C1=C2OCOC2=CC([C@@H]2C3=C([C]4C=CC=CC4=N3)C[C@H]3N2C(=O)CN(C3=O)C)=C1 IEHKWSGCTWLXFU-IIBYNOLFSA-N 0.000 title claims abstract 16
- 239000002904 solvent Substances 0.000 claims abstract description 32
- 238000002425 crystallisation Methods 0.000 claims abstract description 27
- 230000008025 crystallization Effects 0.000 claims abstract description 27
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 30
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 30
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 claims description 18
- 239000000203 mixture Substances 0.000 claims description 17
- BAVYZALUXZFZLV-UHFFFAOYSA-N Methylamine Chemical compound NC BAVYZALUXZFZLV-UHFFFAOYSA-N 0.000 claims description 16
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 claims description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 12
- -1 aliphatic alcohols Chemical class 0.000 claims description 8
- 239000012535 impurity Substances 0.000 claims description 8
- 150000002576 ketones Chemical class 0.000 claims description 7
- 238000010899 nucleation Methods 0.000 claims description 7
- 150000002825 nitriles Chemical class 0.000 claims description 6
- 238000004128 high performance liquid chromatography Methods 0.000 claims description 5
- 238000003556 assay Methods 0.000 claims description 4
- 238000001816 cooling Methods 0.000 claims description 4
- WOXKDUGGOYFFRN-IIBYNOLFSA-N tadalafil Chemical compound C1=C2OCOC2=CC([C@@H]2C3=C(C4=CC=CC=C4N3)C[C@H]3N2C(=O)CN(C3=O)C)=C1 WOXKDUGGOYFFRN-IIBYNOLFSA-N 0.000 description 74
- 238000000746 purification Methods 0.000 description 7
- 239000013078 crystal Substances 0.000 description 5
- 238000010268 HPLC based assay Methods 0.000 description 4
- 239000002585 base Substances 0.000 description 4
- 238000004821 distillation Methods 0.000 description 4
- 238000001953 recrystallisation Methods 0.000 description 4
- 239000007858 starting material Substances 0.000 description 4
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- ZOOGRGPOEVQQDX-KHLHZJAASA-N cyclic guanosine monophosphate Chemical compound C([C@H]1O2)O[P@](O)(=O)O[C@@H]1[C@H](O)[C@H]2N1C(N=C(NC2=O)N)=C2N=C1 ZOOGRGPOEVQQDX-KHLHZJAASA-N 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 3
- 101100189582 Dictyostelium discoideum pdeD gene Proteins 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 2
- 101150098694 PDE5A gene Proteins 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 125000000217 alkyl group Chemical group 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 102100029175 cGMP-specific 3',5'-cyclic phosphodiesterase Human genes 0.000 description 2
- 125000004432 carbon atom Chemical group C* 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000003818 flash chromatography Methods 0.000 description 2
- 239000012458 free base Substances 0.000 description 2
- 150000002894 organic compounds Chemical class 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- DNIAPMSPPWPWGF-GSVOUGTGSA-N (R)-(-)-Propylene glycol Chemical compound C[C@@H](O)CO DNIAPMSPPWPWGF-GSVOUGTGSA-N 0.000 description 1
- QCQCHGYLTSGIGX-GHXANHINSA-N 4-[[(3ar,5ar,5br,7ar,9s,11ar,11br,13as)-5a,5b,8,8,11a-pentamethyl-3a-[(5-methylpyridine-3-carbonyl)amino]-2-oxo-1-propan-2-yl-4,5,6,7,7a,9,10,11,11b,12,13,13a-dodecahydro-3h-cyclopenta[a]chrysen-9-yl]oxy]-2,2-dimethyl-4-oxobutanoic acid Chemical compound N([C@@]12CC[C@@]3(C)[C@]4(C)CC[C@H]5C(C)(C)[C@@H](OC(=O)CC(C)(C)C(O)=O)CC[C@]5(C)[C@H]4CC[C@@H]3C1=C(C(C2)=O)C(C)C)C(=O)C1=CN=CC(C)=C1 QCQCHGYLTSGIGX-GHXANHINSA-N 0.000 description 1
- 208000010228 Erectile Dysfunction Diseases 0.000 description 1
- NTIZESTWPVYFNL-UHFFFAOYSA-N Methyl isobutyl ketone Chemical compound CC(C)CC(C)=O NTIZESTWPVYFNL-UHFFFAOYSA-N 0.000 description 1
- UIHCLUNTQKBZGK-UHFFFAOYSA-N Methyl isobutyl ketone Natural products CCC(C)C(C)=O UIHCLUNTQKBZGK-UHFFFAOYSA-N 0.000 description 1
- 102000004861 Phosphoric Diester Hydrolases Human genes 0.000 description 1
- 108090001050 Phosphoric Diester Hydrolases Proteins 0.000 description 1
- 229940124639 Selective inhibitor Drugs 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000017531 blood circulation Effects 0.000 description 1
- 229940117229 cialis Drugs 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 201000001881 impotence Diseases 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000003389 potentiating effect Effects 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000004648 relaxation of smooth muscle Effects 0.000 description 1
- 238000007363 ring formation reaction Methods 0.000 description 1
- 238000006748 scratching Methods 0.000 description 1
- 230000002393 scratching effect Effects 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D487/00—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, not provided for by groups C07D451/00 - C07D477/00
- C07D487/22—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, not provided for by groups C07D451/00 - C07D477/00 in which the condensed system contains four or more hetero rings
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
- A61P15/00—Drugs for genital or sexual disorders; Contraceptives
- A61P15/10—Drugs for genital or sexual disorders; Contraceptives for impotence
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D471/00—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, at least one ring being a six-membered ring with one nitrogen atom, not provided for by groups C07D451/00 - C07D463/00
- C07D471/12—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, at least one ring being a six-membered ring with one nitrogen atom, not provided for by groups C07D451/00 - C07D463/00 in which the condensed system contains three hetero rings
- C07D471/14—Ortho-condensed systems
Definitions
- the invention is directed to processes of purifying tadalafil by crystallization.
- Tadalafil (6R-trans)-6-(l,3-benzodioxol-5-yl)-2,3,6,7,12,12a-hexahydro-2- methyl-pyrazino[r,2':l,6]pyrido[3,4-b]indole-l,4-dione, with the structural formula shown below, is a white crystalline powder. (CAS# 171596-29-5).
- Tadalafil is a potent and selective inhibitor of the cyclic guanosine monophosphate (cGMP) - specific phosphodiesterase enzyme, PDE5. The inhibition of PDE5 increases the amount of cGMP, resulting in smooth muscle relaxation and increased blood flow. Tadalafil is therefore currently used in the treatment of male erectile dysfunction, and is commercially available as CIALIS ® .
- Tadalafil U.S. Patent No. 5,859,006 describes the synthesis of tadalafil via the cyclization of TDCL (i.e., cis-methyl l,2,3,4-tetrahydro-2-chloroacetyl-l-(3,4- methylenedioxyphenyl)-9H-pyrido[3,4-b]mdole-3-carboxylate) using methylamine by purification by flash chromatography, followed by subsequent crystallization from methanol. Crude tadalafil typically requires additional purification steps, such as multiple extractions, crystallization, and/or flash chromatography, to remove the impurities present in the compound after synthesis is complete.
- TDCL i.e., cis-methyl l,2,3,4-tetrahydro-2-chloroacetyl-l-(3,4- methylenedioxyphenyl)-9H-pyrido[3,4-b]mdo
- the present invention provides a process for the purification of tadalafil that includes the step of crystallizing crude tadalafil from a solution of tadalafil in a solvent selected from the group consisting OfC 2- C 6 aliphatic alcohols and mixtures of ketones or nitriles with a hydroxylic solvent.
- the tadalafil obtained by the above process is free of contaminates, and preferably has an assay of about 100% w/w as measured by HPLC.
- the invention provides a process of purifying tadalafil that includes the step of crystallizing tadalafil using a suitable crystallization solvent.
- This process comprises providing a solution of crude tadalafil in a suitable crystallization solvent, and crystallizing purified tadalafil from the solution.
- the process of the present invention effects a purification of crude tadalafil. In particular, the level of methyl amine, as the free base or as the hydrochloride, is reduced.
- the level of methyl amine in crude tadalafil is about 2% to 10%
- the level of methyl amine, as free base or hydrochloride, in the tadalafil obtained from the method of the present invention will be about 20 ppm to about 300 ppm, as may be determined by one skilled in the art using conventional methods of analysis.
- the process of the invention includes the step of crystallizing crude tadalafil from about 15 to about 100 volumes of a suitable crystallization solvent (i.e, 250 mL of crystallization solvent per 1 gram of tadalafil starting material).
- Crude tadalafil refers to tadalafil that is used as a starting material in the process of the invention. Crude tadalafil typically contains about 10% impurities, in particular the impurity methyl amine or its hydrochloride salt. Crude tadalafil can be obtained from any source or process known in the art; for example, the tadalafil may be obtained by the process disclosed in U.S. Patent No. 5,859,006 or the process disclosed in co-pending U.S. Application No. 60/656,664. Application No. 60/656,664 discloses the preparation of tadalafil in a minimum of process steps by reacting the intermediate TDCL with methylamine under particular reaction conditions.
- pure tadalafil and “purified tadalafil” refer to tadalafil having about 0.5% area by HPLC or less impurities.
- tadalafil obtained from the purification process of the invention has about 0.2% or less impurities as measured by HPLC.
- suitable crystallization solvent refers to a solvent in which crude tadalafil is soluble to the extent of at least about 1 gram in 100 mL.
- Preferred crystallization solvents useful in the method of the invention include aliphatic alcohols and mixtures of at least one ketone or nitrile with a hydroxylic solvent.
- the crystallization solvent is selected from the group consisting of: C 2- C 6 aliphatic alcohols and mixtures of ketones or nitriles with a hydroxylic solvent. More preferably, the solvent is selected from the group consisting of: butanol, a mixture of acetone and methanol, and mixtures of acetone or acetonitrile with water. Most preferably, the solvent is a mixture of water and acetone.
- tadalafil Form I is obtained from the purification process.
- Form I is described in US Application No. 11/265,880, and is characterized by an x-ray diffraction pattern with characteristic reflections at about 7.3, 10.6, 12.6, 14.6, 18.5, 21.8 and 24.3 ⁇ 0.2° 20.
- ketone refers to an water-miscible organic compound having the general formula R 1 (CO)R 2 , wherein each R is a linear or branched alkyl group having from one to about 4 carbon atoms.
- Preferred ketones for use in the process of the present invention are acetone, methyl ethyl ketone and methyl isobutyl ketone.
- a most preferred ketone is acetone.
- nitrile refers to an organic compound having a -CN functional group. Aliphatic nitriles are preferred. Acetonitrile is a particularly preferred nitrile for use in the process of the invention.
- aliphatic alcohols refers to aliphatic alcohols having the general formula C n (H 2 ) JV f 1 OH, wherein n is from at least about 2 to about 6.
- Preferred aliphatic alcohols for use in the practice of this and other embodiments of the present invention are ethanol, 1-propanol, isopropanol and n-butanol.
- n-butanol is a most preferred aliphatic alcohol.
- hydroxylic solvent refers to compounds, liquid at room temperature, having the formula R-OH, wherein R is H or a linear or branched alkyl group having up to about 3 carbon atoms. Water and methanol are useful hydroxylic solvents in the practice of the invention.
- the amount of crystallization solvent used in the process of the invention is an amount sufficient to substantially dissolve the amount of tadalafil starting material.
- substantially dissolve is meant that at least 50% of the tadalafil starting material is dissolved in the solution at about 25°C to about 28°C.
- the amount of recrystallization solvent used in the recrystallization process of the present invention depends on, among other things, the scale of the reaction and the solubility of crude tadalafil in the particular organic solvent. Typically, about 15 to about 100 volumes of recrystallization solvent per gram of tadalafil are used in the process of the invention. Preferably, the amount of recrystallization solvent is about 20 to about 70 volumes per gram of crude tadalafil.
- the process of the invention includes the step of providing a solution of crude tadalafil in a crystallization solvent.
- the solution is provided by combining crude tadalafil and a desired amount of crystallization solvent and, preferably, heating the combination to obtain a solution of crude tadalafil in suitable crystallization solvent.
- the solution is preferably heated for a time sufficient to obtain a clear solution.
- the time required to obtain a clear solution is typically about 30 minutes to six hours, and preferably is about one hour to about three hours.
- the solution is heated to a temperature of about 25°C to about 140 0 C, and preferably is heated to a temperature of about 5O 0 C to about 125°C. More preferably, the solution is heated to a temperature of about 50°C to about 95 0 C. Heating can be performed at a pressure of about 1 atmosphere (760 mrnHg) to about 6 atmospheres.
- the solution is preferably stirred during heating.
- the volume of the solution may be reduced by distillation.
- Crystallization of purified tadalafil from the solution can be achieved by any means known in the art, including precipitation and distillation.
- the solution of tadalafil and crystallization solvent is cooled to a temperature of about -20 0 C to about 9O 0 C to induce crystallization of purified tadalafil. More preferably, the solution is cooled to a temperature of about 10 0 C to about 30 0 C. Cooling of the solution can be performed continuously, in one step, or it can be performed in more than one step. For example, the solution can be cooled first to one temperature and subsequently cooled to a second temperature.
- Crystallization of tadalafil from the solution can include the step of seeding the solution. Seeding is preferably performed during cooling of the solution. Seeding can be performed by any method known in the art, such as by adding a crystal to the solution or scratching the side of a glass reactor containing the solution of tadalafil.
- the process of the invention optionally comprises the steps of filtering and washing the solution after the crystallization of purified tadalafil.
- Purified tadalafil can be washed with at least one volume of water, methanol, acetone, or butanol.
- Example 1 Crystallization of tadalafil in n-butanol
- Crude tadalafil (30 g of dry base) and butanol (2400 mL) were combined to form a solution of crude tadalafil in a 3 liter reactor equipped with a mechanical stirrer, condenser, and thermometer.
- the solution was heated to 125°C and stirred at a rate of 100 rpm for about one hour to obtain a clear solution.
- the solution was cooled to 9O 0 C and seeding was performed.
- the mixture was stirred at about 9O 0 C for one hour and then cooled to 1O 0 C over about 12 hours.
- the mixture was stirred at about 1O 0 C for an additional three hours, filtered under vacuum, and washed with butanol (180 mL).
- Wet tadalafil crystals 28.9 g, 99.5 % by HPLC assay
- Example 2 Crystallization of tadalafil in acetone/ methanol Crude tadalafil (20 g of dry base), acetone (600 mL), and methanol (120 mL) were combined to form a solution of crude tadalafil in a one liter reactor equipped with a mechanical stirrer, a condenser, and a thermometer. The solution was heated to 50 0 C and stirred at a rate of 100 rpm for about one hour to obtain a clear solution. The solution was then filtered and cooled to about 20 0 C and seeding was performed. The mixture was stirred at about 20 0 C for one hour, and then cooled further to 0°C over three hours.
- Example 3 Crystallization of tadalafil in acetone/water
- Crude tadalafil (30 g of dry base), acetone (900 mL), and water (90 mL) were combined to form a solution of crude tadalafil in a one liter reactor equipped with a mechanical stirrer, a condenser, and a thermometer.
- the solution was heated to 30 0 C and stirred at a rate of 200 rpm for about one hour to obtain a clear solution.
- the solution was then cooled to about 12°C and seeding was performed.
- the mixture was stirred at about 12°C for one hour, and then cooled further to -1O 0 C over 12 hours.
- Example 4 Crystallization of tadalafil in acetonitrile/water Crude tadalafil (35 g of dry base), acetonitrile (680.5 mL), and water (160 mL) were combined to form a solution of crude tadalafil in a one liter reactor equipped with a mechanical stirrer, a condenser, and a thermometer. The solution was heated to a jacket temperature of about 85 0 C and stirred at a rate of 150 rpm for about one hour until a clear solution was obtained and distillation had begun. The distillation continued until half of the volume of the solution remained. The temperature of the solution was about 77°C. The solution was stirred at this temperature for another two hours.
- the solution was then cooled to about 10 0 C over about 3 hours, and then stirred at this temperature for another 13 hours.
- the solution was then filtered under vacuum and washed with acetonitrile (170 mL) and water (40 mL) to obtain wet tadalafil crystals (21.45 g, 99.9 % by HPLC assay).
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Abstract
The invention is directed to a method of purifying tadalafil by crystallization of tadalafil from a solution of crude tadalafil in a suitable crystallization solvent.
Description
PROCESS OF PURIFYING TADALAFIL
RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application No. 60/656,664, filed February 25, 2005; U.S. Provisional Application No. 60/683,058, filed May 19, 2005; U.S. Provisional Application No. 60/736,807, filed November 14, 2005; and U.S. Provisional Application No. 60/737,080, filed November 15, 2005 and U.S. Provisional Application No. 60/677,514, filed May 3, 2005. The contents of these applications are incorporated herein by reference.
FIELD OF THE INVENTION The invention is directed to processes of purifying tadalafil by crystallization.
BACKGROUND OF THE INVENTION
Tadalafil, (6R-trans)-6-(l,3-benzodioxol-5-yl)-2,3,6,7,12,12a-hexahydro-2- methyl-pyrazino[r,2':l,6]pyrido[3,4-b]indole-l,4-dione, with the structural formula shown below, is a white crystalline powder. (CAS# 171596-29-5). Tadalafil is a potent and selective inhibitor of the cyclic guanosine monophosphate (cGMP) - specific phosphodiesterase enzyme, PDE5. The inhibition of PDE5 increases the amount of cGMP, resulting in smooth muscle relaxation and increased blood flow. Tadalafil is therefore currently used in the treatment of male erectile dysfunction, and is commercially available as CIALIS ®.
Tadalafil
U.S. Patent No. 5,859,006 describes the synthesis of tadalafil via the cyclization of TDCL (i.e., cis-methyl l,2,3,4-tetrahydro-2-chloroacetyl-l-(3,4- methylenedioxyphenyl)-9H-pyrido[3,4-b]mdole-3-carboxylate) using methylamine by purification by flash chromatography, followed by subsequent crystallization from methanol. Crude tadalafil typically requires additional purification steps, such as multiple extractions, crystallization, and/or flash chromatography, to remove the impurities present in the compound after synthesis is complete. Such purification processes increase the cost of producing tadalafil. Also, when repeating the US '006 process, about 250 volumes of methanol were necessary for the crystallization step. Inexpensive and simple methods of purifying crude tadalafil are desirable to allow the preparation of tadalafil in a cost efficient manner.
SUMMARY QF THE INVENTION
The present invention provides a process for the purification of tadalafil that includes the step of crystallizing crude tadalafil from a solution of tadalafil in a solvent selected from the group consisting OfC2-C6 aliphatic alcohols and mixtures of ketones or nitriles with a hydroxylic solvent.
The tadalafil obtained by the above process is free of contaminates, and preferably has an assay of about 100% w/w as measured by HPLC.
DETAILED DESCRIPTION OF THE INVENTION
The invention provides a process of purifying tadalafil that includes the step of crystallizing tadalafil using a suitable crystallization solvent. This process comprises providing a solution of crude tadalafil in a suitable crystallization solvent, and crystallizing purified tadalafil from the solution. The process of the present invention effects a purification of crude tadalafil. In particular, the level of methyl amine, as the free base or as the hydrochloride, is reduced. For example, when the level of methyl amine in crude tadalafil is about 2% to 10%, the level of methyl amine, as free base or hydrochloride, in the tadalafil obtained from the method of the present invention will be about 20 ppm to about 300 ppm, as may be determined by one skilled in the art using conventional methods of analysis.
The process of the invention includes the step of crystallizing crude tadalafil from about 15 to about 100 volumes of a suitable crystallization solvent (i.e, 250 mL of crystallization solvent per 1 gram of tadalafil starting material).
"Crude tadalafil" refers to tadalafil that is used as a starting material in the process of the invention. Crude tadalafil typically contains about 10% impurities, in particular the impurity methyl amine or its hydrochloride salt. Crude tadalafil can be obtained from any source or process known in the art; for example, the tadalafil may be obtained by the process disclosed in U.S. Patent No. 5,859,006 or the process disclosed in co-pending U.S. Application No. 60/656,664. Application No. 60/656,664 discloses the preparation of tadalafil in a minimum of process steps by reacting the intermediate TDCL with methylamine under particular reaction conditions.
As used herein, the terms "pure tadalafil" and "purified tadalafil" refer to tadalafil having about 0.5% area by HPLC or less impurities. Preferably, tadalafil obtained from the purification process of the invention has about 0.2% or less impurities as measured by HPLC.
As used herein, the term "free of contaminates", in reference to tadalafil, refers to tadalafil that has an assay of at least about 99.5% w/w. As such, tadalafil that is free of contaminates does not contain either organic or inorganic impurities. As used herein, "suitable crystallization solvent" refers to a solvent in which crude tadalafil is soluble to the extent of at least about 1 gram in 100 mL. Preferred crystallization solvents useful in the method of the invention include aliphatic alcohols and mixtures of at least one ketone or nitrile with a hydroxylic solvent.
Preferably, the crystallization solvent is selected from the group consisting of: C2-C6 aliphatic alcohols and mixtures of ketones or nitriles with a hydroxylic solvent. More preferably, the solvent is selected from the group consisting of: butanol, a mixture of acetone and methanol, and mixtures of acetone or acetonitrile with water. Most preferably, the solvent is a mixture of water and acetone.
When the solvent is a mixture of acetone and water, tadalafil Form I, as analyzed by XRD, is obtained from the purification process. Form I is described in US Application No. 11/265,880, and is characterized by an x-ray diffraction pattern
with characteristic reflections at about 7.3, 10.6, 12.6, 14.6, 18.5, 21.8 and 24.3 ± 0.2° 20.
As used herein, the term "ketone" refers to an water-miscible organic compound having the general formula R1(CO)R2, wherein each R is a linear or branched alkyl group having from one to about 4 carbon atoms. Preferred ketones for use in the process of the present invention are acetone, methyl ethyl ketone and methyl isobutyl ketone. A most preferred ketone is acetone.
As used herein, the term "nitrile" refers to an organic compound having a -CN functional group. Aliphatic nitriles are preferred. Acetonitrile is a particularly preferred nitrile for use in the process of the invention.
As used herein, the term "aliphatic alcohols" refers to aliphatic alcohols having the general formula Cn(H2)JVf1OH, wherein n is from at least about 2 to about 6. Preferred aliphatic alcohols for use in the practice of this and other embodiments of the present invention are ethanol, 1-propanol, isopropanol and n-butanol. n-butanol is a most preferred aliphatic alcohol.
As used herein, the term "hydroxylic solvent" refers to compounds, liquid at room temperature, having the formula R-OH, wherein R is H or a linear or branched alkyl group having up to about 3 carbon atoms. Water and methanol are useful hydroxylic solvents in the practice of the invention. The amount of crystallization solvent used in the process of the invention is an amount sufficient to substantially dissolve the amount of tadalafil starting material. By "substantially dissolve" is meant that at least 50% of the tadalafil starting material is dissolved in the solution at about 25°C to about 28°C. The amount of recrystallization solvent used in the recrystallization process of the present invention depends on, among other things, the scale of the reaction and the solubility of crude tadalafil in the particular organic solvent. Typically, about 15 to about 100 volumes of recrystallization solvent per gram of tadalafil are used in the process of the invention. Preferably, the amount of recrystallization solvent is about 20 to about 70 volumes per gram of crude tadalafil. The process of the invention includes the step of providing a solution of crude tadalafil in a crystallization solvent. In one embodiment, the solution is provided by combining crude tadalafil and a desired amount of crystallization solvent and,
preferably, heating the combination to obtain a solution of crude tadalafil in suitable crystallization solvent. The solution is preferably heated for a time sufficient to obtain a clear solution. The time required to obtain a clear solution is typically about 30 minutes to six hours, and preferably is about one hour to about three hours. The solution is heated to a temperature of about 25°C to about 1400C, and preferably is heated to a temperature of about 5O0C to about 125°C. More preferably, the solution is heated to a temperature of about 50°C to about 950C. Heating can be performed at a pressure of about 1 atmosphere (760 mrnHg) to about 6 atmospheres. The solution is preferably stirred during heating. Optionally, the volume of the solution may be reduced by distillation.
Crystallization of purified tadalafil from the solution can be achieved by any means known in the art, including precipitation and distillation. Preferably, the solution of tadalafil and crystallization solvent is cooled to a temperature of about -200C to about 9O0C to induce crystallization of purified tadalafil. More preferably, the solution is cooled to a temperature of about 100C to about 300C. Cooling of the solution can be performed continuously, in one step, or it can be performed in more than one step. For example, the solution can be cooled first to one temperature and subsequently cooled to a second temperature.
Crystallization of tadalafil from the solution can include the step of seeding the solution. Seeding is preferably performed during cooling of the solution. Seeding can be performed by any method known in the art, such as by adding a crystal to the solution or scratching the side of a glass reactor containing the solution of tadalafil.
The process of the invention optionally comprises the steps of filtering and washing the solution after the crystallization of purified tadalafil. Purified tadalafil can be washed with at least one volume of water, methanol, acetone, or butanol.
Having described the invention with reference to certain preferred embodiments, other embodiments will become apparent to one skilled in the art from consideration of the specification. The invention is further defined by reference to the following nonlimiting examples describing in detail the process of the invention in certain of its embodiments.
EXAMPLES
Example 1: Crystallization of tadalafil in n-butanol
Crude tadalafil (30 g of dry base) and butanol (2400 mL) were combined to form a solution of crude tadalafil in a 3 liter reactor equipped with a mechanical stirrer, condenser, and thermometer. The solution was heated to 125°C and stirred at a rate of 100 rpm for about one hour to obtain a clear solution. The solution was cooled to 9O0C and seeding was performed. The mixture was stirred at about 9O0C for one hour and then cooled to 1O0C over about 12 hours. The mixture was stirred at about 1O0C for an additional three hours, filtered under vacuum, and washed with butanol (180 mL). Wet tadalafil crystals (28.9 g, 99.5 % by HPLC assay) were obtained.
Example 2: Crystallization of tadalafil in acetone/ methanol Crude tadalafil (20 g of dry base), acetone (600 mL), and methanol (120 mL) were combined to form a solution of crude tadalafil in a one liter reactor equipped with a mechanical stirrer, a condenser, and a thermometer. The solution was heated to 500C and stirred at a rate of 100 rpm for about one hour to obtain a clear solution. The solution was then filtered and cooled to about 200C and seeding was performed. The mixture was stirred at about 200C for one hour, and then cooled further to 0°C over three hours. The mixture was stirred at 00C for an additional hour, and then filtered under vacuum, and washed with methanol (120 mL). Wet tadalafil crystals (12.4 g, 100 % by HPLC assay) were obtained.
Example 3: Crystallization of tadalafil in acetone/water
Crude tadalafil (30 g of dry base), acetone (900 mL), and water (90 mL) were combined to form a solution of crude tadalafil in a one liter reactor equipped with a mechanical stirrer, a condenser, and a thermometer. The solution was heated to 300C and stirred at a rate of 200 rpm for about one hour to obtain a clear solution. The solution was then cooled to about 12°C and seeding was performed. The mixture was stirred at about 12°C for one hour, and then cooled further to -1O0C over 12 hours. The mixture was stirred at -100C for an additional 6 hours, and then filtered under vacuum, and washed with methanol (120 mL). Wet tadalafil crystals (22.35 g, 99.7 %
by HPLC assay) were obtained. According to the XRD analysis of the obtained material, tadalafil Form I was obtained.
Example 4: Crystallization of tadalafil in acetonitrile/water Crude tadalafil (35 g of dry base), acetonitrile (680.5 mL), and water (160 mL) were combined to form a solution of crude tadalafil in a one liter reactor equipped with a mechanical stirrer, a condenser, and a thermometer. The solution was heated to a jacket temperature of about 850C and stirred at a rate of 150 rpm for about one hour until a clear solution was obtained and distillation had begun. The distillation continued until half of the volume of the solution remained. The temperature of the solution was about 77°C. The solution was stirred at this temperature for another two hours. The solution was then cooled to about 100C over about 3 hours, and then stirred at this temperature for another 13 hours. The solution was then filtered under vacuum and washed with acetonitrile (170 mL) and water (40 mL) to obtain wet tadalafil crystals (21.45 g, 99.9 % by HPLC assay).
Claims
1. A process of purifying tadalafil comprising the steps of: a) providing a solution of crude tadalafil in a solvent selected from the group consisting OfC2-C6 aliphatic alcohols and mixtures of ketones or nitriles with a hydroxylic solvent; and b) crystallizing purified tadalafil from the solution.
2. The process of claim 1, wherein the solvent is selected from the group consisting of: butanol, a mixture of acetone and methanol, and mixtures of acetone or acetonitrile with water.
3. The process of claim 2, wherein the solvent is a mixture of acetone and water.
4. The process of any of claims 1, 2, or 3 wherein the solution contains about 15 to about 100 volumes of solvent per gram of crude tadalafil.
5. The process of claim 4, wherein the solution contains about 20 to about 70 volumes of solvent per gram of crude tadalafil.
6. The process of any of claims 1 or 5 wherein the solution is heated to a temperature of about 25°C to about 140°C prior to crystallization of tadalafil.
7. The process of claim 6, wherein the solution is heated to a temperature of about 500C to about 125°C.
8. The process of claim 7, wherein the solution is heated to a temperature of about 500C to about 95°C.
9. The process of any of claims 1 or 8 wherein the crystallizing of step b) is performed by cooling the solution to a temperature of about -200C to about 45°C.
10. The process of claim 9, wherein the crystallizing of step b) is performed by cooling the solution to a temperature of about 100C to about 35°C.
11. The process of any of claims 1 or 10 further comprising seeding the solution.
12. The process of any of claims 1, 5, 7, 9, or 11 or wherein the purified tadalafil contains about 0.5% area by HPLC or less of impurities.
13. The process of claim 12, wherein the purified tadalafil contains about 0.2% area by HPLC or less of impurities.
14. The process of any of claims 1, 5, 7, 9, or 115 wherein the purified tadalafil has an assay of at least about 99.5% w/w.
15. The process of claim 14, wherein the purified tadalafil has an assay of about 100% w/w.
16. The process of any of claims 1 , 5, 7, 9, or 11 wherein the purified tadalafil contains about 20 ppm to about 300 ppm of methyl amine.
17. Tadalafil containing about 20 ppm to about 300 ppm of methyl amine.
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2007551492A JP2008527012A (en) | 2005-02-25 | 2006-02-27 | Purification method of tadalafil |
| MX2007010431A MX2007010431A (en) | 2005-02-25 | 2006-02-27 | Process of purifying tadalafil. |
| EP06736625A EP1851223A1 (en) | 2005-02-25 | 2006-02-27 | Process of purifying tadalafil |
| CA002599458A CA2599458A1 (en) | 2005-02-25 | 2006-02-27 | Process of purifying tadalafil |
| IL184188A IL184188A0 (en) | 2005-02-25 | 2007-06-25 | Process of purifying tadalafil |
Applications Claiming Priority (10)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US65666405P | 2005-02-25 | 2005-02-25 | |
| US60/656,664 | 2005-02-25 | ||
| US67751405P | 2005-05-03 | 2005-05-03 | |
| US60/677,514 | 2005-05-03 | ||
| US68305805P | 2005-05-19 | 2005-05-19 | |
| US60/683,058 | 2005-05-19 | ||
| US73680705P | 2005-11-14 | 2005-11-14 | |
| US60/736,807 | 2005-11-14 | ||
| US73708005P | 2005-11-15 | 2005-11-15 | |
| US60/737,080 | 2005-11-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2006091980A1 true WO2006091980A1 (en) | 2006-08-31 |
Family
ID=36579968
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/US2006/007338 WO2006091980A1 (en) | 2005-02-25 | 2006-02-27 | Process of purifying tadalafil |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US20070004737A1 (en) |
| EP (1) | EP1851223A1 (en) |
| JP (1) | JP2008527012A (en) |
| KR (1) | KR20070099034A (en) |
| CA (1) | CA2599458A1 (en) |
| IL (1) | IL184188A0 (en) |
| MX (1) | MX2007010431A (en) |
| WO (1) | WO2006091980A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009148341A1 (en) * | 2008-06-03 | 2009-12-10 | Zaklady Farmaceutyczne Polpharma Sa | Process for preparation of tadalafil |
| CN104844600A (en) * | 2015-05-13 | 2015-08-19 | 山东罗欣药业集团股份有限公司 | Tadalafil compound and composition thereof |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111272919B (en) * | 2020-03-31 | 2022-05-24 | 广西-东盟食品检验检测中心 | Identification method for illegally added cyclohexyl nortadalafil in food |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5859006A (en) * | 1994-01-21 | 1999-01-12 | Icos Corporation | Tetracyclic derivatives; process of preparation and use |
| WO2004011463A1 (en) * | 2002-07-31 | 2004-02-05 | Lilly Icos, Llc. | Modified pictet-spengler reaction and products prepared therefrom |
| WO2006050458A2 (en) * | 2004-11-02 | 2006-05-11 | Teva Pharmaceutical Industries, Ltd. | Tadalafil crystal forms and processes for preparing them |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9511220D0 (en) * | 1995-06-02 | 1995-07-26 | Glaxo Group Ltd | Solid dispersions |
| RU2214391C2 (en) * | 1998-05-29 | 2003-10-20 | Хфм Интернэшнл, Инк. | Method for preparing purified terephthalic and isophthalic acid from xylenes mixture |
| US6821975B1 (en) * | 1999-08-03 | 2004-11-23 | Lilly Icos Llc | Beta-carboline drug products |
| PL361230A1 (en) * | 2000-10-05 | 2004-10-04 | Biogal Gyogyszergyar Rt. | Pravastatin sodium substantially free of pravastatin lactone and epi-pravastatin, and compositions containing same |
| WO2003074536A1 (en) * | 2002-03-05 | 2003-09-12 | Toagosei Co., Ltd. | Novel organosilicon compound, optically active isomers thereof, process for producing the organosilicon compound, and use thereof |
| CA2395871A1 (en) * | 2002-07-26 | 2004-01-26 | The Institutes For Pharmaceutical Discovery, Llc | Substituted indolealkanoic acids derivatives and formulations containing same for use in treatment of diabetic complications |
| JP2005035944A (en) * | 2003-07-16 | 2005-02-10 | Takeda Chem Ind Ltd | Styrene derivative, method for producing the same, and application thereof |
-
2006
- 2006-02-27 WO PCT/US2006/007338 patent/WO2006091980A1/en active Application Filing
- 2006-02-27 MX MX2007010431A patent/MX2007010431A/en unknown
- 2006-02-27 JP JP2007551492A patent/JP2008527012A/en active Pending
- 2006-02-27 KR KR1020077019488A patent/KR20070099034A/en not_active Application Discontinuation
- 2006-02-27 EP EP06736625A patent/EP1851223A1/en not_active Withdrawn
- 2006-02-27 CA CA002599458A patent/CA2599458A1/en not_active Abandoned
- 2006-02-27 US US11/364,599 patent/US20070004737A1/en not_active Abandoned
-
2007
- 2007-06-25 IL IL184188A patent/IL184188A0/en unknown
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5859006A (en) * | 1994-01-21 | 1999-01-12 | Icos Corporation | Tetracyclic derivatives; process of preparation and use |
| WO2004011463A1 (en) * | 2002-07-31 | 2004-02-05 | Lilly Icos, Llc. | Modified pictet-spengler reaction and products prepared therefrom |
| WO2006050458A2 (en) * | 2004-11-02 | 2006-05-11 | Teva Pharmaceutical Industries, Ltd. | Tadalafil crystal forms and processes for preparing them |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009148341A1 (en) * | 2008-06-03 | 2009-12-10 | Zaklady Farmaceutyczne Polpharma Sa | Process for preparation of tadalafil |
| CN104844600A (en) * | 2015-05-13 | 2015-08-19 | 山东罗欣药业集团股份有限公司 | Tadalafil compound and composition thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| US20070004737A1 (en) | 2007-01-04 |
| JP2008527012A (en) | 2008-07-24 |
| EP1851223A1 (en) | 2007-11-07 |
| CA2599458A1 (en) | 2006-08-31 |
| MX2007010431A (en) | 2007-10-11 |
| KR20070099034A (en) | 2007-10-08 |
| IL184188A0 (en) | 2007-10-31 |
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