Hypervalent iodine(iii) promoted C-H/C-H amination/annulation tandem reactions: synthesis of benzimidazoles from simple anilines and aldehydes

A novel hypervalent iodine mediated cascade transformation of anilines and aldehydes to benzimidazoles was developed. A series of 1,2-disubstituted benzimidazoles were achieved with aromatic, heteroaromatic, and aliphatic aldehydes. In this procedure, the initial condensation of anilines with aldehydes afforded N-arylimine intermediates which underwent C-H/C-H amination/annulation to generate the desired products in moderate to excellent yields. This reaction is an extremely simple reaction system with good functional group tolerance, and water is the only byproduct formed.