H2O2/HCl as a new and efficient system for synthesis of 2-substituted benzimidazoles

Abstract

The system, H2O2/HCl, oxidises carbon–nitrogen bonds for the synthesis of benzimidazoles from aldehydes and diamines in water at 100°C. Both aryl aldehydes bearing electron-donating and electron-withdrawing substituents afforded desired benzimidazoles in excellent yields. This procedure is also applicable to substituted o-phenylenediamines, which produced 2-phenylbenzimidazoles smoothly in excellent yields. The simplicity of the system, the use of water as the solvent, large-scale synthesis and easy work-up are main advantages of this procedure.