Copper/ascorbic acid dyad as a catalytic system for selective aerobic oxidation of amines.

A new, environmentally benign system based on an ascorbic acid (vitamin C)/copper dyad is presented, which facilitates the oxidation of amines to carbonyl compounds. The oxidation utilizes aerobic oxygen as the ultimate electron scavenger, which accepts electrons in a cascade-like fashion via a Cu(+)/Cu(2+) and ascorbic/dehydroascorbic acid couple. Dehydroascorbic acid, the oxidation agent, finally oxidizes amine substrates in a selective fashion after forming a Schiff base intermediate. The selectivity as well as generality of the method is demonstrated on various substrates.