Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D405/00—Heterocyclic compounds containing both one or more hetero rings having oxygen atoms as the only ring hetero atoms, and one or more rings having nitrogen as the only ring hetero atom
  • C07D405/14—Heterocyclic compounds containing both one or more hetero rings having oxygen atoms as the only ring hetero atoms, and one or more rings having nitrogen as the only ring hetero atom containing three or more hetero rings
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P9/00—Drugs for disorders of the cardiovascular system
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P9/00—Drugs for disorders of the cardiovascular system
  • A61P9/12—Antihypertensives

Definitions

• Olmesartan medoxomil is the name commonly given to (5-methyl-2-oxo-1,3-dioxo--4-yl)methyl 1-(2′-(1H-tetrazol-5-yl)biphenyl-4-yl)methyl)-4-(2-hydroxypropan-2-yl)-2-propyl-1H-imidazole-5-carboxylate, shown as (1) below.
• This chemical is known as an antagonist of angiotensin-II receptors and acts as an antihypertensive agent.
• the first process includes the step of alkylating ethyl 4-(1-hydroxy-1-methylethyl)-2-propylimidazole-5-carboxylate (2) with 4-[2-trityltetrazol-5-yl)phenyl]benzylbromide (3) and isolating the resulting product as shown below in scheme 3.
• This step is followed in WO2007/17135 by the steps of hydrolysis of the ethyl ester (4), the esterification with 4-substituted methyl-5-methyl-1,3-dioxolene-2-one derivative (7) and the subsequent deprotection of the trityl protection group in a one-pot process, i.e. without any isolation during the process, as shown below in scheme 4.
• the presented one-pot process includes partial purification of the intermediate trityl olmesartan medoxomil (6) by extraction and exchange of the solvent before the last reaction step.
• the second method provides the same alkylation reaction step with isolation of the alkylation product and an alternative synthetic approach in a one-pot process.
• the one-pot process comprises the hydrolysis of the ethyl ester (4), the esterification with 4-substituted methyl-5-methyl-1,3-dioxolene-2-one derivative (7) and the subsequent cycloaddition reaction of the cyano moiety forming the tetrazole group. But no experimental support is given for this approach.
• the present invention provides a process for the preparation of trityl olmesartan medoxomil, the process comprising the steps:
• the present invention provides trityl olmesartan medoxomil (6) obtained by a process according to the first aspect of the invention.
• the present invention provides a process of preparing olmesartan medoxomil (1), characterized by comprising the process according to the first aspect of the invention and converting trityl olmesartan medoxomil (6) to olmesartan medoxomil (1).
• the present invention provides a process of obtaining pharmaceutical formulation comprising olmesartan medoxomil, characterized by comprising the process according to previous aspect of the invention and further comprising tableting.
• the present aspect involves a “one-pot process” in which intermediates are not isolated and preferably no material is removed or exchanged.
• the same type of solvent and the same base are used in steps a) to c).
• the process of the invention allows for improvements in efficiency to be obtained as it is possible to use less solvent and less base as it does not need to be changed during the process.
• the use of a one-pot solution for manufacturing trityl olmesartan medoxomil is simple and cost effective.
• the resultant trityl olmesartan medoxomil is a crucial intermediate in the synthesis of olmesartan medoxomil.
• step a) is performed at the temperature between 20 and 90° C., preferably between 30 and 60° C.
• step b is performed at the temperature between 20 and 70° C., preferably between 40 and 60° C.
• step c is performed at the temperature between 20 and 70° C., preferably between 40 and 60° C.
• Trityl olmesartan medoxomil (6) obtained by a process according to any one of the first aspect or (i) to (ix).
• a process of preparing olmesartan medoxomil (1) characterized by comprising the process according to the first aspect or (i) to (ix) and converting trityl olmesartan medoxomil (6) to olmesartan medoxomil (1).
• the process according to (xi), wherein converting trityl olmesartan medoxomil (6) to olmesartan medoxomil (1) comprises the steps of:
• lithium hydroxide hydrate is used as the base in each step, as is preferred in the invention.
• the use of this soft base in all of the reaction steps minimises the formation of impurities.
• the whole amount of base necessary can be added at the beginning of the reaction, or can be added stepwise during the one-pot process.
• different base can be used in any step.
• the first step of the invention is alkylating ethyl 4-(1-hydroxy-1-methylethyl)-2-propylimidazole-5-carboxylate (2) with 4-[2-(trityltetrazol-5-yl)phenyl]benzyl bromide (3) in an organic solvent, in the presence of a base, to produce trityl olmesartan ethyl ester (4).
• the reaction is started by dissolving (2) and (3) in an appropriate organic solvent and adding a base.
• An appropriate type of organic solvent is selected from a group of polar aprotic solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, 1-methyl-2-pyrrolidone, dimethylsulfoxide, acetonitrile and mixtures thereof, preferably N,N-dimethylacetamide is used.
• a base can be selected from a group of alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide; a group of metal carbonates such as sodium carbonate, potassium carbonate, caesium carbonate; a group of metal alkoxides or a group of organic amines, preferably alkali metal hydroxides are used, most preferable is lithium hydroxide.
• 1 equivalent of the base can be added and the following amount can be added step-wise during the one-pot process or the whole amount of the base can be added at the beginning of the alkylating reaction step.
• 1 equivalent of the base is added at the beginning of the alkylating reaction step and the rest is added stepwise during the one-pot process.
• the whole amount of the added base is ranging between 2.5 to 10 equivalents, preferably between 3 and 5 equivalents.
• the alkylating reaction step is done by stirring the reaction mixture for 0.5 to 24 hours, preferably for 1 to 4 hours, at the temperature between 20 and 90° C., preferably between 30 and 60° C. After alkylating reaction step is completed the resulting product trityl olmesartan ethyl ester (4) is not isolated from the reaction mixture.
• the next step, b) involves hydrolysing the trityl olmesartan ethyl ester (4) in an organic solvent, in the presence of a base, to form trityl olmesartan salt (5).
• This reaction step is done by optionally adding the next portion of a base to the reaction mixture obtained by completion of the previous alkylation step.
• a base is selected from a group of alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, preferably lithium hydroxide is used.
• the amount of the added base is ranging between 1 and 5 equivalents, preferably 1 to 3 equivalents of the base are added.
• reaction mixture is stirred for 5 to 120 hours, preferably between 24 and 72 hours at the temperature ranging from 20 to 70° C., preferably at the temperature between 40 and 60° C.
• the resulting product trityl olmesartan salt (5) is not isolated from the reaction mixture.
• step c esterifying the trityl olmesartan salt (5) with 4-chloromethyl-5-methyl-1,3-dioxolene-2-one (7) in an organic solvent, in the presence of a base, to form trityl olmesartan medoxomil (6). This is done by optionally adding the next portion of a base to the reaction mixture obtained by completion of the previous hydrolysing step.
• a base can be selected from a group of alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide or a group of metal carbonates such as sodium carbonate, potassium carbonate, ceasium carbonate, preferably lithium hydroxide or potassium carbonate in an amount of 0.5 to 1.5 equivalent are added to the reaction mixture.
• Addition of the base is followed by addition of 4-chloromethyl-5-methyl-1,3-dioxolene-2-one (7).
• reagent (7) is dissolved in an organic solvent and the solution is added dropwise to the reaction mixture, most preferably the same solvent as in reaction mixture is used for preparation of solution of (7). (7) is added in an amount of 1 to 2.5 equivalents, preferably in an amount between 1.2 to 2 equivalents.
• the reaction is performed by stirring the reaction mixture for 2 to 24 hours, preferably 3 to 8 hours at the temperature ranging between 20 and 70° C., preferably at the temperature between 40 and 60° C.
• esterification reaction step is completed the resulting product trityl olmesartan medoxomil (6) is isolated from the reaction mixture.
• the mixture is poured into large amount of water or water acetone mixture (V/V 95:5) and the product is precipitated from the medium.
• Intermediate (6) is collected by filtration and optionally purified by recrystallisation to obtain final intermediate for preparation of olmesartan medoxomil of high purity.
• one-pot process we mean that the relevant steps are performed in sequence without isolating the product of each step, furthermore the process of the invention is additionally simplified by omitting removal or exchange of any other component of the reaction mixture.
• Using a one-pot process is a simple and cost effective method of organic synthesis but is only commercially valuable where the level of impurities can be minimised to give a reasonable yield.
• the inventors have found that use of a one-pot process gives good results, particularly with the use of lithium hydroxide hydrate as a base. Such a procedure does not allow unacceptable levels of unreacted intermediates and side products to accumulate and because the one pot reaction does not include the last chemical step of preparation of the active pharmaceutical ingredient, further purification is conveniently carried out.
• the impurities are efficiently removed by simple recrystallisation of (6) and/or during the further step of reaction of deprotection of (6), during the isolation and purification of final product (1) in order to reach an active pharmaceutical ingredient of high chemical purity substantially free of unreacted intermediates and side products such as olmesartan ethyl ester (8) (Scheme 6).
• olmesartan medoxomil can be prepared by converting trityl olmesartan medoxomil into olmesartan medoxomil by any known or invented process for cleavage of trityl protection group.
• Scheme 7 below shows a synthetic method for deprotection of trityl olmesartan medoxomil, which may be applied in the invention.
• the process of converting trityl olmesartan medoxomil to olmesartan medoxomil comprises the steps of: d) forming a solution containing the trityl olmesartan medoxomil (6) and hydrohalic acid; e) forming olmesartan medoxomil hydrohalide salt in solid form and isolating the olmesartan medoxomil hydrohalide salt; and d) converting the olmesartan medoxomil hydrohalide salt to olmesartan medoxomil (1).
• This method of forming olmesartan medoxomil is particularly advantageous as it leads to the product of high purity.
• (6) is deprotected in the solution containing hydrohalic acid comprising a mixture of one or more water miscible organic solvents and water.
• the water miscible organic solvent is preferably selected from the group consisting of a C 1 to C 6 alcohol, a C 1 to C 6 ketone, a C 1 to C 6 nitrile, a C 1 to C 6 amide, a C 1 to C 6 ether, dimethyl sulfoxide, or mixtures thereof, wherein the water miscible organic solvent preferably comprises acetone, acetonitrile, ethanol, t-butanol, or 1,4-dioxane and most preferably comprises acetone.
• Hydrohalic acids are preferably used as water solutions in concentrations above 10 w/w %, most preferably commercial concentrated acids like 48% or 62% hydrobromic acid or 35-38% hydrochloric acid. 48% hydrobromic acid is the most preferable.
• the organic solvent to water ratio is preferably between 10:1 and 1:4 by volume, more preferably between 4:1 and 1:1 by volume.
• the deprotection, preferably detritylation reaction is carried out at temperatures from 20° C. to reflux preferably from 25 to 30° C.
• water Prior to separating the precipitated triphenylmethanol, water is added to the mixture to change the organic solvent to water ratio to about 1:3 to about 1:5, preferably to about 1:4.
• Triphenylmethanol is subsequently separated from the solution by any means known in the art, such as centrifugation or filtration.
• the filtrate is concentrated to completely or partially remove organic solvents and the resulting aqueous suspension is stirred at temperatures ranging from 0° C. to room temperature to achieve maximum yield, then filtered to collect olmesartan medoxomil hydrohalide salt.
• (6) is deprotected in tetrahydrofuran in the presence of hydrohalic acid.
• the detritylation reaction is carried out at temperatures from 20° C. to reflux preferably from 25 to 30° C., and isolation is performed by cooling to ⁇ 10 to 5° C. preferably to around 0° C.
• triphenylmethanol remains dissolved, while olmesartan medoxomil hydrohalide salt is precipitated by said cooling or by adding antisolvent selected from aromatic or aliphatic hydrocarbons and acyclic ethers, particularly preferably acyclic ethers, most preferably diisopropylether.
• Olmesartan medoxomil hydrohalide salt can optionally be recrystallised, preferably from tetrahydrofuran.
• the olmesartan medoxomil hydrohalide salt is dissolved in the mixture of at least one water miscible solvent and water.
• Suitable water miscible organic solvents include, but are not limited to, acetone, acetonitrile, lower alcohols, tetrahydrofuran, 1,4-dioxane, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide. Alcohols, acetone and acetonitrile are preferred; acetone is the most preferred.
• the organic solvent to water ratio is preferably between 2:1 and 1:3 by volume, more preferably about 1:2 by volume.
• aqueous solution of inorganic base selected from alkali and alkaline earth carbonates, hydrogen carbonates, hydroxides, alkoxides, preferably hydrogen carbonates, more preferably NaHCO 3 .
• the amount of base used should be such to raise the pH to about 5 to 8, more preferably 5.5 to 6.5.
• the temperature of the mixture should be maintained at about 0 to about 30° C., more preferably at about 20 to about 25° C., until olmesartan medoxomil is precipitated, and then at about 0 to about 5° C. to achieve maximum yield.
• the precipitated olmesartan medoxomil is collected using any method known in the art, such as centrifugation or filtration.
• olmesartan medoxomil may be recrystalized from a suitable solvent such as acetone, acetonitrile, methanol, ethanol, propanol, 2-propanol, methyl acetate, ethyl acetate, isopropyl acetate and mixtures thereof or mixtures thereof with water; preferably acetone and acetonitrile, more preferably acetonitrile.
• a suitable solvent such as acetone, acetonitrile, methanol, ethanol, propanol, 2-propanol, methyl acetate, ethyl acetate, isopropyl acetate and mixtures thereof or mixtures thereof with water; preferably acetone and acetonitrile, more preferably acetonitrile.
• Olmesartan medoxomil obtained by a process comprising any of the aforementioned embodiments can be further used in a process of obtaining the pharmaceutical formulation comprising olmesartan medoxomil.
• the pharmaceutical formulation comprising olmesartan medoxomil can be prepared by methods well known to a person skilled in the pharmaceutical technology.
• olmesartan medoxomil is mixed with pharmaceutically acceptable excipient, which can be selected from a group of binder, filler, disintegrant, surfactant, glidant, lubricant, wetting agent, colouring agent, acidifying or alkalizing agents, and the like.
• pharmaceutically acceptable excipient which can be selected from a group of binder, filler, disintegrant, surfactant, glidant, lubricant, wetting agent, colouring agent, acidifying or alkalizing agents, and the like.
• prepared mixture is further used in tableting. Tableting may be performed after wet granulation or preparation of a mixture for direct
• reaction mixture is stirred for 3 h at 50° C. and then an additional 1.05 g (25 mmol) of lithium hydroxide hydrate is added to the reaction mixture.
• the reaction mixture is stirred for the next 40 hours at 50° C., which is followed by addition of the third portion of lithium hydroxide hydrate (0.35 g, 8.33 mmol) and portion-wise addition of a solution of 3.84 g (24.6 mmol) of 4-chloromethyl-5-methyl-1,3-dioxolene-2-one (7) (94%) in 10 mL of N,N-dimethylacetamide.
• reaction mixture is stirred for 46 hours at 50° C. and then 2.53 g (18.32 mmol) of K 2 CO 3 and portion-wise 4.0 g (23.0 mmol) of 4-chloromethyl-5-methyl-1,3-dioxolene-2-one (7) (85%) in 10 mL of N,N-dimethylacetamide are added.
• the reaction mixture is stirred at 50° C. for the next 5 hours to complete the reaction.
• Olmesartan medoxomil hydrobromide is then dissolved in a mixture of water (55 ml) and acetone (30 ml). To a clear solution saturated aqueous NaHCO 3 is added to raise pH to 5.6. The mixture is stirred for 1 hour at room temperature and 2 hours at 0° C. The precipitate is filtered, washed with water and then recrystallised from acetonitrile (45 ml) to give olmesartan medoxomil.
• Trityl olmesartan medoxomil (250 g, 310 mmol) (97.3% area) is dissolved in THF (1560 ml) and 48% aqueous hydrobromic acid (70.6 ml, 625 mmol) is added slowly. The mixture is stirred for at 25° C. After 1 hour the precipitate forms. The mixture is stirred for 1 additional hour at 25° C., then cooled to ⁇ 5° C. and stirred for 1.5 hours at ⁇ 5° C. The precipitate is filtered. 940 ml of THF is added to the precipitate and the mixture is stirred for 1 h at 25° C. and then 1 hour at ⁇ 5° C.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Cardiology (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Bioinformatics & Cheminformatics (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Heart & Thoracic Surgery (AREA)
• Pharmacology & Pharmacy (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
• Plural Heterocyclic Compounds (AREA)

Applications Claiming Priority (5)

Publications (1)

Family

ID=39789494

Family Applications (2)

Family Applications After (1)

Country Status (9)

Families Citing this family (17)

Citations (2)

Family Cites Families (14)

• 2008
  • 2008-08-07 CN CN200880102267.4A patent/CN101778842B/zh not_active Expired - Fee Related
  • 2008-08-07 BR BRPI0815111-3A2A patent/BRPI0815111A2/pt not_active Application Discontinuation
  • 2008-08-07 CA CA2707334A patent/CA2707334C/en not_active Expired - Fee Related
  • 2008-08-07 US US12/672,264 patent/US20110224271A1/en not_active Abandoned
  • 2008-08-07 AT AT08786993T patent/ATE528305T1/de not_active IP Right Cessation
  • 2008-08-07 SI SI200830507T patent/SI2176253T1/sl unknown
  • 2008-08-07 JP JP2010519468A patent/JP5685082B2/ja not_active Expired - Fee Related
  • 2008-08-07 WO PCT/EP2008/060400 patent/WO2009019304A1/en active Application Filing
  • 2008-08-07 EP EP08786993A patent/EP2176253B1/en not_active Not-in-force
  • 2008-08-07 EP EP08786996.2A patent/EP2173741B1/en not_active Not-in-force
  • 2008-08-07 CN CN200880102268A patent/CN101778843A/zh active Pending
  • 2008-08-07 WO PCT/EP2008/060396 patent/WO2009019303A2/en active Application Filing
  • 2008-08-07 CA CA2707365A patent/CA2707365A1/en not_active Abandoned
  • 2008-08-07 US US12/672,267 patent/US8592474B2/en active Active
  • 2008-08-07 BR BRPI0815134-2A2A patent/BRPI0815134A2/pt not_active Application Discontinuation
  • 2008-08-07 JP JP2010519469A patent/JP2010535743A/ja active Pending

Patent Citations (2)

Also Published As

Similar Documents

Legal Events