Synthesis of Substituted Benzimidazoles and Benzoxazoles by Iron-catalysed Reductive Carbonylation of Aryl Iodides

This work describes a novel iron-catalysed approach for the synthesis of aryl-substituted benzimidazoles and benzoxazoles. The methodology employs reductive carbonylation using readily available aryl iodides and aryl amines as precursors, with carbon monoxide serving as the efficient carbonyl source. The reaction proceeds under mild conditions with the addition of hydrosilanes and bases. Notably, aryl aldehydes are generated in situ from the aryl iodides, which subsequently react with o-phenylenediamine or 2-aminophenol to afford the desired products in high yields. The structures of the synthesized benzimidazoles and benzoxazoles were confirmed using 1H and 13C NMR spectroscopy and mass spectrometry. Iron-catalysed reductive carbonylation offers a streamlined and cost-effective method for synthesizing benzimidazoles and benzoxazoles. This innovative approach, uitilizing aryl iodides and in situ generated aldehydes, enables high-yield synthesis of these important heterocycles. image