Synthesis of 2-trifluoromethyl benzimidazoles, benzoxazoles, and benzothiazoles via condensation of diamines or amino(thio)phenols with CF3CN

Abstract

A new and efficient method is developed for the synthesis of 2-trifluoromethyl benzimidazoles, benzoxazoles, and benzothiazoles in good to excellent yields by the condensation of diamines or amino(thio)phenols with in situ generated CF₃CN. Additionally, the synthetic utility of the 2-trifluoromethyl benzimidazole and benzoxazole products is demonstrated via gram scale synthesis. The mechanistic study suggests that the reaction proceeds via the nucleophilic addition of trifluoroacetonitrile to the amino group of the diamine derivatives to form an imidamide intermediate, followed by intramolecular cyclization.