A novel and practical synthesis of substituted 2-ethoxy benzimidazole: candesartan cilexetil

作者:Wang, Ping; Zheng, Guo-jun; Wang, Ya-ping; Wang, Xiang-jing; Li, Yan; Xiang, Wen-sheng*
来源:Tetrahedron, 2010, 66(29): 5402-5406.
DOI:10.1016/j.tet.2010.05.037

摘要

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.