Low-cost acetate-catalyzed efficient synthesis of benzimidazoles using ambient CO2 as a carbon source under mild conditions

Abstract

Using CO2 as a low-cost C1 resource to produce value-add products was considered as a promising strategy for the sustainable carbon cycle. Herein, a base-promoted reductive functionalization of CO2 and 1,2-phenylenediamine for the synthesis of benzimidazole was developed using hydrosilane as an H-donor. Commercially available acetate salt CH3COOK used as a budget catalyst could furnish various benzimidazoles with moderate to excellent yields (42-95%) under mild conditions (40 °C, 1 bar CO2). The reaction mechanism undergoing cascade N-formylation, cyclization, and reduction was preliminarily confirmed by attenuated total reflection (ATR) technique and control experiments.