WO2004087691A1 - A process for the synthesis of losartan potassium - Google Patents
A process for the synthesis of losartan potassium Download PDFInfo
- Publication number
- WO2004087691A1 WO2004087691A1 PCT/IN2003/000230 IN0300230W WO2004087691A1 WO 2004087691 A1 WO2004087691 A1 WO 2004087691A1 IN 0300230 W IN0300230 W IN 0300230W WO 2004087691 A1 WO2004087691 A1 WO 2004087691A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- losartan
- potassium
- reaction mass
- product
- losartan potassium
- Prior art date
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D403/00—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00
- C07D403/02—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00 containing two hetero rings
- C07D403/10—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00 containing two hetero rings linked by a carbon chain containing aromatic rings
Definitions
- the invention is related to an improved process for the synthesis of Losartan Potassium, an angiotensin II receptor antagonist.
- losartan potassium plays an effective role in patients having difficulty in tolerating ACE inhibitors.
- the chemical name of losartan potassium is 2-n-Butyl-4-Chloro-l [((2'-tetrazol-5-yl)-l,l'- bisphenyl-4-yl)methyl]-imidazole-5-methanol potassium.
- Losartan potassium (shown as the compound of formula (I) below) is known in the art as able to be synthesized by reacting its acid (shown as the compound of formula (II) below) with KOH.
- the intermediate acid form (II) in turn is known as able to be synthesized by detritylation of 2-n-butyl-4-chloro-5-hydroxymethyl- 1 -[((2' -triphenylmethyltetrazole-5-yl) biphenyl-4-yl) methyl] imidazole (shown as the compound of formula (III) below)
- Trityl Losartan (the reactant of form (III) below) is known in the art. See 34 I MED. CHEM. 2525-27 (1991); 59 J.ORG. CHEM. 6391-94 (1994); US 5,138,069. Trityl Losartan (and the Losartan acid) and may alternatively be prepared using the reactions and techniques described in US Patent 5,138,069 and patent application number W093/10106.
- Trityl Losartan the reactant of form (III) of Losartan acid (II) by acid- catalyzed cleavage of trityl group from Trityl Losartan (III) is disclosed in Us 5,281,603. Another method disclosed to prepare Losartan acid from trityl losartan is disclosed in Us 5,281,604 in this process. Trityl Losartan (III) is refluxed in a mixture of methanol and tetrahydrofuran for 18 hours to get losartan acid (II).
- the Richter Gedeon approach was found to be easy and superior to the existing methods, however was found to suffer from various drawbacks as summarized below: a) The product obtained does not pass desired solubility in various solvents. To make the product improve in quality, it needs an extra purification as per the Richter Gedeon application.
- Patent application number WO 02/094816 discloses use of acetone, ethyl acetate, acetonitrile and toluene as anti-solvents and has similar problems of recovery and reuse of solvents and high cost of production. Since isolation of the product is simply by precipitation using anti solvents, the product needs further purification to pass the required tests, in this case also.
- polymorphic form I is the addition of aqueous solution of (I) to a refluxing mixture of cyclohexane and isopropyl alcohol followed by azeotropic distilling out cyclohexane /isopropyl alcohol/water ternary azeotrope at 64° C while the form I crystallizes out at 69° C .
- Patent application number W098/18787 describes a method which also starts with a solution of Losartan Potassium (I) in aqueous isopropyl alcohol and is heated to distill out water-isopropyl alcohol mixture to lower the water content to 2.6%.
- the invention is related to a process for the synthesis of Losartan Potassium of formula (I), which comprises detritylation of Trityl Losartan of formula (III) in a primary alcohol (we use the term "primary alcohol” to mean an alcohol of the structure R-OH, wherein the R group is a CI to approximately C4 chain) with a potassium tertiary alkoxide (e.g. potassium tertiary butoxide) as a reagent, without needing to isolate the corresponding free acid of formula II.
- the Losartan Potassium product (I) is isolated by crystallization from a solvent such as isopropyl alcohol or tetrahydrofuran, or, optionally, a combination of both in a suitable ratio.
- the invention deals with the single pot synthesis of Losartan Potassium (I) of very high purity.
- the process starts with Trityl Losartan (III), but uses a single solvent such as isopropyl alcohol or tetrahydrofuran. This leads to reduction of the solvent usage and losses. This process eliminates the need for extra purification of (I).
- the use of single solvents (isopropyl alcohol or tetrahydrofuran) also makes the single solvent easily recoverable and reusable in the process, reducing the cost of production significantly.
- a combination of isopropyl alcohol and tetrahydrofuran in suitable proportions have also been used, giving high yields and purity. However, in this case the solvent mixture requires fractional distillation after recovery.
- the present process involves refluxing a mixture of Trityl Losartan (III) and an equimolar amount of potassium tertiary butoxide (KOBut) together in solvent comprised of a primary alcohol.
- the primary alcohol is preferably present in a volume of from three to six times the volume with respect to the Trityl Losartan (III).
- We prefer the reaction be maintained for about 3-10 hours, preferably for 4-8 hours, albeit reaction times may be adjusted depending on solvent concentration, temperature, etc....
- the reaction mixture is cooled down to 0 to - 10° C. This cooling may be done with the primary alcohol present, or after it is substantially removed. We prefer that it is done after about 50% of the primary alcohol is removed.
- the product is then filtered o remove the by-product (namely trityl methyl ether).
- the filtered reaction mass is then concentrated to remove primary alcohol. It is preferable to remove primary alcohol before crystallizing the product from isopropyl alcohol or tetrahydrofuran, but the complete removal up to the last traces is not essential, as far as quality of the product is concerned.
- the advantage of the modified process disclosed herein over prior art is that the product contains almost similar chemical profile, but the new process gives a product of high quality which meets current drug substance purity requirements, without requiring extra purification step.
- Another major advantage of this process is the use of a single solvent (isopropyl alcohol or tetrahydrofuran), which requires only 1.0-6.0 times the volume of solvent, as compared to larger volumes of solvents (as is done in prior art solvent mixtures).
- a single solvent improves solvent recovery and reusability, making the process cost effective, eco-friendly as well as plant friendly.
- the reaction mass is cooled to 0.5° C and filtered.
- the product (Losartan Potassium) is washed with chilled tetrahydrofuran (15 ml).
- the final product is dried at 45-50° C under vacuum for 6 hours.
- the percentage yield of Losartan Potassium is 90.62%.
- the reaction mass is cooled to 0-5° C and filtered.
- the product (Losartan Potassium) is washed with chilled isopropyl alcohol (15 ml).
- the final product is dried at 45 - 50° C under vacuum for 6 hours.
- the percentage yield of Losartan Potassium is 79.95%.
- Tetrahydrofuran 120 ml is charged and the reaction mass stirred at 50-55° C for 15 minutes. The reaction mass is cooled to 30° C and stirred for 5 hours. The reaction mass is then cooled to 0-5° C and filtered. The product (Losartan Potassium) is washed with chilled tetrahydrofuran (15 ml). The final product is dried at 45-50° C under vaccum for 6 hours to remove any residual tetrahydrofuran. The percentage yield of losartan potassium is 90.04%
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP03751250A EP1608641A1 (en) | 2003-04-03 | 2003-06-27 | A process for the synthesis of losartan potassium |
AU2003269470A AU2003269470A1 (en) | 2003-04-03 | 2003-06-27 | A process for the synthesis of losartan potassium |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IN335/MUM/2003 | 2003-04-03 | ||
IN335MU2003 | 2003-04-03 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2004087691A1 true WO2004087691A1 (en) | 2004-10-14 |
Family
ID=33105001
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/IN2003/000230 WO2004087691A1 (en) | 2003-04-03 | 2003-06-27 | A process for the synthesis of losartan potassium |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP1608641A1 (en) |
AU (1) | AU2003269470A1 (en) |
WO (1) | WO2004087691A1 (en) |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2001081336A1 (en) * | 2000-04-21 | 2001-11-01 | Richter Gedeon Vegyészeti Gyár Rt. | Process for the synthesis of a known tetrazol derivative |
WO2002094816A1 (en) * | 2001-05-18 | 2002-11-28 | Aurobindo Pharma Limited | Process for the crystallization of losartan potassium |
-
2003
- 2003-06-27 EP EP03751250A patent/EP1608641A1/en not_active Withdrawn
- 2003-06-27 WO PCT/IN2003/000230 patent/WO2004087691A1/en not_active Application Discontinuation
- 2003-06-27 AU AU2003269470A patent/AU2003269470A1/en not_active Abandoned
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2001081336A1 (en) * | 2000-04-21 | 2001-11-01 | Richter Gedeon Vegyészeti Gyár Rt. | Process for the synthesis of a known tetrazol derivative |
WO2002094816A1 (en) * | 2001-05-18 | 2002-11-28 | Aurobindo Pharma Limited | Process for the crystallization of losartan potassium |
Also Published As
Publication number | Publication date |
---|---|
AU2003269470A1 (en) | 2004-10-25 |
EP1608641A1 (en) | 2005-12-28 |
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