Organophotocatalytic Generation of N- and O-Centred Radicals Enables Aerobic Oxyamination and Dioxygenation of Alkenes

A cooperative TEMPO and photoredox catalytic strategy was applied for the first time to the direct conversion of N-H and O-H bonds into N-and O-centred radicals, enabling a general and selective oxidative radical oxyamination and dioxygenation of various beta,gamma-unsaturated hydrazones and oximes. In the reaction, O-2 was employed not only as a terminal oxidant but also as the oxygen source. This protocol provided efficient access to the synthesis of various synthetically and biologically important pyrazoline, pyridazine and isoxazoline derivatives under metal-free and mild reaction conditions. Mechanistic studies revealed that the cooperative organophotocatalytic system functions through two single-electron-transfer (SET) processes.