Synthesis of α,β-Unsaturated Carbonyl Compounds via Cu/TEMPO/O2 Aerobic Catalytic System.

An N,N,N-type Cu(II) complex-catalyzed desaturation method for converting alcohols, ketones, lactones, and lactams to their α,β-unsaturated carbonyl compounds is reported. The dehydrogenation reaction can be conducted with a green terminal oxidant O2 without requiring strong acid/base or stoichiometric oxidants. The Cu(II) complex/TEMPO/O2 system uses a non-noble catalyst, and a green terminal oxidant as well as demonstrates high activity and functional group tolerance. Notably, H2O is the byproduct produced and overoxidation is not observed during the reaction process. The proposed mechanism was investigated via high-resolution mass spectrometry (HRMS), in situ FT-IR spectrometry, and GC analysis, and the formation of intermediates of α,β-unsaturated carbonyl compounds from the aerobic dehydrogenation of α,β-saturated counterparts was observed.