Unprecedented selective synthesis of imines by photo-oxidative coupling under N2O atmosphere

The synthesis of imines was unprecedently performed using nitrous oxide (N2O) as a highly selective oxidative agent for the photocatalytic homo-coupling of amines. In a similar way, unsymmetrical imines were produced through cross-coupling of amines with alcohols. Promisingly, this greenhouse gas showed excellent performances towards the target reactions when photocatalytically activated at atmospheric pressure, with silver photodeposited on titanium dioxide as catalyst. Relevantly, reactions under N2O atmosphere exhibited high conversion rates and turn-over frequencies, and higher selectivities than the ones carried out under a dioxygen atmosphere. Mechanisms for both reactions were proposed with release of nitrogen and water as benign by-products.