Microwave-Assisted, Rapid, Solvent-Free Aza-Michael Reaction by Perchloric Acid Impregnated on Silica Gel

Highly efficient solvent-free aza-Michael additions of a variety of amines to ,-unsaturated carbonyl compounds under microwave-irradiation conditions catalyzed by perchloric acid impregnated on silica gel (HClO4/SiO2) is reported. The reactions are completed within 2-7min in a microwave oven to produce the corresponding adducts in excellent yields, and the catalyst can be recovered and reused.