AN IMPROVED PROCESS FOR THE PREPARATION OF AZILSARTAN MEDOXOMIL

摘要

The present invention relates to an improved process for the preparation of azilsartan or its esters or salts thereof. Specifically, the invention provides a method for the preparation of highly pure methyl 1-[[2-(4,5-dihydro-5-oxo-4H-1,2,4-oxa-diazol-3-yl)biphenyl-4-yl]methyl]-2-ethoxy-1H-benzimidazole-7-carboxylate an intermediate compound of formula (4) for azilsartan medoxomil with reduced content of desethyl impurity. The invention also involves the use of highly pure methyl 1-[[2-(4,5-dihydro-5-oxo-4H-1,2,4-oxadiazol-3-yl)biphenyl-4-yl]methyl]-2-ethoxy-1H-benzimidazole-7-carboxylate in the preparation of azilsartan or its esters or salts thereof, preferably medoxomil with reduced content of desethyl impurity.