A Stepwise Electrochemical Baeyer–Villiger Oxidation with Water as the Oxygen Source

Baeyer–Villiger oxidation is a method with a 125-year history that produces lactones through a synergistic mechanism by reaction with stoichiometric peracids. Therefore, substituted lactones can be obtained from only substituted cyclic ketones. In this context, an electrochemical Baeyer–Villiger oxidation was developed using a CeO₂@PbO₂@Ti electrode, which produces substituted lactones through a stepwise mechanism. PbO₂, in combination with a benzoic acid molecular catalyst, can generate and utilize reactive oxygen species from electrochemical water splitting to serve as the oxidant. CeO₂ is designed to promote the stepwise mechanism while suppressing the synergistic mechanism. Therefore, substituted lactone can be produced from unsubstituted cyclic ketone with high selectivity (77%) and yield (20 mM) through a carbocation rearrangement process. The developed stepwise electrochemical Baeyer–Villiger oxidation, using water as the oxygen source, offers a new green approach to organic synthesis.