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 - Guchhait, Sankar K.; Madaan, Chetna (Synlett, 2009)