Oxidation of α,β-Unsaturated Ketones by Organophotocatalysis Using Rhodamine 6G Under Visible Light Irradiation: Insight into Reaction Mechanism

The oxidative transformation of α,β-unsaturated ketones was investigated under the visible light-induced photocatalytic conditions using rhodamine 6G as an organophotocatalyst. In this organocatalysis, a mild co-oxidant BrCCl3 acts not only as a quencher toward the activated photocatalyst species having reductant property but also as a brominating reagent for the intermediate radicals. This study shows that the bromine atom-transfer to intermediate radicals from BrCCl3 is a key step in the reaction mechanism of our oxidation method.