Facile Synthesis of Benzimidazoles via N -Arylamidoxime Cyclization.

A facile synthesis of benzimidazoles was described by a one-pot process containing acylation-cyclization of N -arylamidoxime. This method provided an alternative synthesis of benzimidazoles with a certain diversity of substituted groups in acceptable yields (up to 96%). More importantly, the construction of bis-benzimidazole ( 8 ), the key intermediate for making telmisartan, was achieved by adopting this method that enabled avoiding the undesired nitration with nitric/sulfuric acid and the cyclization in polyphosphoric acid in the existing operations.