Alpha-Oxygenation of Ketones Using TEMPO Disproportionation.

The alpha-oxygenation of ketones via acid-driven TEMPO disproportionation is reported. This straightforward and robust protocol from simple starting materials exhibits an excellent substrate scope in terms of scaffold substitutions, selectivity, and functional group tolerance, with substrate limitations elucidated and highlighted. Furthermore, the mechanism was probed by way of UV-visible spectroscopy, deuterium scrambling experiments, kinetic isotope effect, and Hammett analysis to illustrate the reaction dynamics.