Asymmetric Ring Opening/Cyclization/Retro‐Mannich Reaction of Cyclopropyl Ketones with Aryl 1,2‐Diamines for the Synthesis of Benzimidazole Derivatives

Abstract

A highly efficient asymmetric ring-opening/cyclization/retro-Mannich reaction of cyclopropyl ketones with aryl 1,2-diamines has been realized using a chiral N,N'-dioxide/Sc(III) catalyst. Benzimidazoles containing chiral side chains were generated under mild reaction conditions in excellent outcomes (up to 99 % yield and 97 % ee). This method also provides efficient access to chiral benzimidazole-substituted amide and cycloheptene derivatives.