Mechanism of Copper-Catalyzed Oxygenation of Ketones

Article abstract of DOI:10.1021/jo00193a013

Deoxybenzoin (1) is converted by a Cu(II)-py-Et3N-MeOH-O2 (py=pyridine) system to a mixture of benzil (2), bidesyl (3), and the cleavage products PhCHO and PhCOOH.A product study comparing reactivities of 1 and 2 under identical conditions established (i) that the conversion of 1 to 3 is effected by Cu(II) alone, (ii) that PhCHO is generated only from 1, in a reaction that requires both Cu(II) and O2, and (iii) that 2 undergoes C-C cleavage only in the presence of H2O, forming PhCOOH exclusively, in a reaction that requires Cu(II) but not O2. α-Methyldeoxybenzoin (5) undergoes an exceptionally slow but similar reaction ( giving the tertiary α-ketol 6 rather than diketone 2).Mechanisms for these reactions are presented, and the significance of the results is discussed.