Oxidation and photochemical reactions of 3‐phenyl‐2H‐1,4‐benzoxazines

Abstract 3‐Phenyl‐2H‐1, 4‐benzoxazines 4‐oxides are light sensitive compounds, irradiation leads to 3‐phenyl‐2H‐1,4‐benoxazines and to their 3‐oxidized derivatives, whenever possible. Intermediate oxaziridines are formed during the photolysis and transformed into stable nitroxide radicals. The structure of these radicals was confirmed through peracid oxidation of 3‐phenyl‐2H‐1,4‐benzoxazines and 3‐phenyl‐3, 4‐dihydro‐2H‐1,4‐benzoxazines. A reaction mechanism is proposed on the basis of experimental observations.