One-pot Synthesis of Benzimidazoles and Benzothiazoles in the Presence of Fe(HSO4)3 as a New and Efficient Oxidant

A series of substituted benzimidazoles and benzothiazoles were prepared through the one-pot reaction of o-phenylenediamine and o-aminothiophenol with various aldehydes in the presence of ferric hydrogensulfate both in EtOH and water as solvent. The reactions proceed smoothly in excellent yield, high chemoselectivity and with an easy work-up.