Control of Selectivity in FeCl3 -Catalyzed Aerobic Oxidation of Cycloketones.

The FeCl3 -catalyzed aerobic oxidation of ketones always gives rise to the α-C-C cleavage product, having challenges to afford hydroxyl keto compounds. Here we report an effective control of the main product from keto acid to α-hydroxyl ketone, by reducing the concentration of FeCl3 catalyst, together with the use of DMSO as the solvent. In addition, mechanistic investigations suggested the same FeCl3 -coordinated peroxide intermediate for both hydroxylation and C-C cleavage routes, and emphasize the role of DMSO as both ligand and reductant. This work provides a new approach for selective aerobic oxidation under Lewis acid catalysis.