Aerobic oxidation of amines to imines catalyzed by bulk gold powder and by alumina-supported gold

Both bulk gold powder (∼50 μm particle size) and alumina-supported gold (50–150 nm) are highly active catalysts for the aerobic oxidative dehydrogenation of amines (CH–NH) to imines (Cdouble bond; length as m-dashN) under the mild conditions of 1 atm O2 and 100 °C. Reactions using the 5% Au/Al2O3 catalyst make efficient use of the gold metal and offer a practical synthesis of imines from amines. These studies add to the growing list of reactions that are catalyzed by bulk gold metal.