Photoinduced Oxygen Transfer using Nitroarenes for the Anaerobic Cleavage of Alkenes

Herein we report a visible light promoted method for the cleavage of alkenes into valuable carbonyl derivatives using economical nitroarenes as oxygen transfer reagents. This approach serves as an operationally simple and practical alternative to mainstream oxidative cleavage protocols, such as ozonolysis and the Lemieux–Johnson reaction, with comparable efficiency and without their considerable limitations. Mechanistic studies support that the transformation occurs via a solvent separated ion-pair complex and that the nitroarene undergoes direct photoexcitation to trigger a radical cycloaddition event with alkenes leading to a 1,3,2-dioxazolidine intermediate that fragments to give the desired carbonyl products. A combination of radical clock experiments and in situ PhotoNMR spectroscopy revealed the identities of the key radical species and the putative aryl 1,3,2-dioxazolidine intermediate, respectively.