An Efficient, Regioselective, Versatile Synthesis of N-Fused 2-and 3-Aminoimidazoles via Ugi-Type Multicomponent Reaction Mediated by Zirconium(IV) Chloride in Polyethylene Glycol-400

An Ugi-type multicomponent reaction of heterocyclic amidines with aldehydes and isocyanides catalyzed by zirconium(IV)chloride in PEG-400 was developed. The protocol offers the rapid, environment friendly, regioselective and versatile synthesis of medicinally important N-fused 2- and 3-aminoimidazoles in good to high yields. The combination of catalyst and solvent, that was judiciously explored, was crucial for regioselectivity and versatility of the method.