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.