Photoinduced Oxygen Transfer using Nitroarenes for the Anaerobic Cleavage of Alkenes

Herein we report a visible light promoted method for the anaerobic cleavage of alkenes into carbonyl compounds using nitroarenes as oxygen transfer reagents. This approach serves as a safe and practical alternative to mainstream oxidative cleavage protocols, such as ozonolysis and the Lemieux–Johnson reaction. A wide range of alkenes possessing oxidatively sensitive functionalities underwent anaerobic cleavage to generate carbonyl derivatives with high efficiency and regioselectivity. Mechanistic studies support that the transformation occurs via a solvent-separated ion-pair complex and the nitroarene is the sole photoabsorbing species. Direct photoexcitation of the nitroarenes empowers a radical cycloaddition event with alkenes leading to a 1,3,2-dioxazolidine intermediate, which fragments to give the 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.