- A method for preparing ester
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The invention provides a preparation method of candesartan cilexetil. The preparation method comprises steps I-IV. The step I concretely comprises the following substeps of adding candesartan and dichloromethane in a reaction container; slowly and dropwise adding triethylamine at the temperature of 10-15 DEG C; raising the temperature of a reaction system to 21-25 DEG C after dropwise adding of the triethylamine is fnished; adding triphenylchloromethane in batches; reacting for 3-4 hours; adding 0.1 mol/L HCl at one step after reaction is complete and adjusting pH (potential of hydrogen) to be 5-6; then slowly and dropwise adding 9 mol/L HCl and adjusting pH to be 2-3; leaving standstill; separating a water layer and an organic layer; adding saturated salt water in the organic layer to wash the organic layer; leaving standstill to achieve a layering effect; separating out the organic layer; performing decompress concentration on the organic layer to remove the dichloromethane; adding absolute ethyl alcohol in residual viscous substances; raising temperature to 45-50 DEG C; stirring for 3 hours; stopping heating after a large amount of white solids are separated out; reducing to room temperature; performing suction filtration; washing filter cakes with ethyl alcohol; and drying to obtain trityl candesartan.
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- AN IMPROVED PROCESS FOR THE PREPARATION OF CANDESARTAN CILEXETIL, POLYMORPHIC FORMS OF N-TRITYL CANDESARTAN AND THEIR USES THEREOF
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The present invention provides an improved process for the preparation of candesartan cilexetil comprising the use of polymorphic Form A and Form B of N-trityl candesartan. Also, provided herein, new polymorphic Form A and Form B of N-trityl candesartan and the processes for their preparation.
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- A noveland practical synthesis of substituted 2-ethoxy benzimidazole: Candesartan cilexetil
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A novel and practical synthetic route for the preparation of candesartan cilexetil from methyl 2-amino-3-nitrobenzoate is described.The key steps are the reaction of methyl 2-bromo-3-(diethoxy-methyleneamino)benzoate with (2-(1-trityl-1H-tetrazol-5-yl) biphenyl-4-yl) methanamine and the final formation of 2-ethoxy benzimidazole ring via intramolecular N-arylation.The final ring closure process could be utilized to prepare other 2-substituted benzimidazoles.The method is simple for operation and suitable for industrial production.
- Wang, Ping,Zheng, Guo-Jun,Wang, Ya-Ping,Wang, Xiang-Jing,Li, Yan,Xiang, Wen-Sheng
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experimental part
p. 5402 - 5406
(2010/08/19)
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- PROCESS FOR THE PREPARATION OF CANDESARTAN CILEXETIL
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The present invention relates to an improved process for the preparation of tritylated candesartan acid of formula (I) comprising a step of, reacting candesartan acid of formula (II) with trityl chloride in the presence of a base in a ketonic solvent.
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Page/Page column 6
(2010/08/22)
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- Process for the preparation of tetrazolyl compounds
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The invention provides a method for preparing candesartan cilexetil and related tetrazolyl compounds. More particularly, the invention relates to the preparation of candesartan cilexetil and related tetrazolyl compounds and includes a method of removing a protective group (e.g., triphenylmethane (trityl) protecting group) from an N-protected tetrazolyl compound using a Lewis acid in an inert solvent and in the presence of an alcohol (e.g., reacting an N-protected tetrazolyl compound with ZnCl2 in the presence of an alcohol).
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Page/Page column 4
(2009/10/06)
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- AN IMPROVED PROCESS FOR THE PREPARATION OF CANDESARTAN CILEXETIL
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The present invention relates to an improved process for the preparation of tritylated candesartan acid of formula (I) comprising a step of, reacting candesartan acid of formula (II) with trityl chloride in the presence of a base in a ketonic solvent.
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Page/Page column 14-15
(2009/03/07)
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- PROCESS FOR PREPARATION OF CANDESARTAN CILEXETIL
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There was provided a process for preparing candesartan cilexetil, the said process comprises hydrogenating a solution of trityl candesartan cilexetil in an alcohol with hydrogen in the presence of a palladium catalyst. Mixture of toluene and methanol was added to 1-(Cyclohexyloxy carbonyloxy)ethyl-2-ethoxy-1-[[2'-(N-triphenylmethyltetrazole-5-yl)biphenyl-4-yl] methyl]benzimidazole-7-carboxylate and hydrogenated at room temperature with hydrogen at atmospheric pressure in the presence of palladium on carbon until the hydrogen uptake was ceased. Filtered over celite bed, washed the bed with a mixture of toluene and methanol, filtrate was collected and concentrated. Co- distilled with acetonitrile, acetonitrile was added, stirred at room temperature, cooled to 0°C. stirred, filtered, washed with chilled acetonitrile and dried to get candesartan cilexetil.
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Page/Page column 4-5
(2010/01/30)
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- CRYSTALLINE 1-(CYCLOHEXYLOXYCARBONYLOXY) ETHYL 1-((2'-CYANOBIPHENYL-4-YL)METHYL)-2-ETHOXY-1H-BENZO[D]IMIDAZOLE-7-CARBOXYLATE AND A PROCESS FOR ITS PREPARATION
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The present invention relates to 1-(cyclohexyloxycarbonyloxy)ethyl 1-((2'-cyanobiphenyl-4-yl)methyl)-2-ethoxy-1H-benzo[d]imidazole-7-carboxylate in crystalline form and a process for its preparation, which is useful intermediate in the preparation of candesartan cilexetil. The present invention also relates to the preparation of candesartan cilexetil and pharmaceutical composition comprising candesartan cilexetil.
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Page/Page column 27-28
(2008/12/08)
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- PROCESS FOR THE PREPARATION OF AMORPHOUS AND CRYSTALLINE FORMS OF CANDESARTAN CILEXETIL USING COLUMN CHROMATOGRAPHY
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The present invention provides processes for the preparation of amorphous and crystalline candesartan cilexetil with quality that complies to Ph.Eur./ICH Guidelines by an economical way using easy accessible substances and pure starting compounds.
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Page/Page column 20; 21
(2008/06/13)
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- AN IMPROVED PROCESS FOR THE PREPARATION OF CANDESARTAN CILEXETIL
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The invention relates to process for the preparation of Candesartan cilexetil. More particularly, it relates to the preparation of pure candesartan cilexetil by the deprotection of Trityl candesartan cilexetil with inorganic acids.
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Page/Page column 6-7
(2008/06/13)
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- METHOD FOR OBTAINING BENZIMIDAZOLE DERIVATIVES AND INTERMEDIATES THEREOF
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The present invention relates to a method for obtaining benzimizadole derivatives and intermediates thereof, preferably, for obtaining Candesartan and Candesartan cilexetil. Said method allows the benzimizadole derivatives to be obtained with a higher yield.
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- METHOD FOR PRODUCTION OF CANDESARTAN
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The invention relates to novel methods for the production of Candesartan, or a protected form of Candesartan, a Candesartan salt or ester, compounds of application in said method, methods for production thereof, use thereof in said method, a novel polymorph of Candesartan cilexetil, a method for production and use thereof for production of a medicament.
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Page/Page column 27
(2010/11/08)
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- PROCESS FOR THE SYNTHESIS OF TETRAZOLES
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A process for the synthesis of tetrazol derivative has been developed which starts from a tetrazole derivative where acidic hydrogen atom has been replaced by a protecting group and the deprotection is performed with a catalytic amount of organic acid and can proceed in an aqueous solvent.
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Page/Page column 12
(2008/06/13)
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- PREPARATION OF CANDESARTAN CILEXETIL
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The invention encompasses processes for the synthesis of cilexetil trityl candesartan from the reaction of trityl candesartan with cilexetil halide in the presence of a base and a low boiling organic solvent. Optionally, the reaction may be conducted in the presence of a phase transfer catalyst.
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Page/Page column 9
(2008/06/13)
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- Production method of aminobenzene compound
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The present invention is to provide an industrially useful production method of an aminobenzene compound represented by the formula: which is characterized by reacting a mixture of a mono-halogeno compound represented by the formula: and di-halogeno compound represented by the formula: with a compound of the formula:
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