Metal-free aerobic oxidative coupling of amines to imines

Mesoporous carbon nitride (mpg-C(3)N(4)) polymer can function as a metal-free photocatalyst to activate O(2) for the selective oxidation of benzyl alcohols with visible light, avoiding the cost, toxicity, and purification problems associated with corresponding transition-metal systems. By combining the surface basicity and semiconductor functions of mpg-C(3)N(4), the photocatalytic system can realize a high catalytic selectivity to generate benzaldehyde. The metal-free photocatalytic system also selectively converts other alcohol substrates to their corresponding aldehydes/ketones, demonstrating a potential pathway of accessing traditional mild radical chemistry with nitroxyl radicals.