A metal-free and mild approach to 1,3,4-oxadiazol-2(3H)-ones via oxidative C-C bond cleavage using molecular oxygen.

A mild metal-free approach to 1,3,4-oxadiazol-2(3H)-ones via 1,3,4-oxadiazin-5(6H)-ones is described. This novel transformation, promoted by the electron-withdrawing p-substituents on the phenyl group at the α-carbonyl position, features a tandem reaction consisting of oxidative hydroxylation and C-C bond cleavage using molecular oxygen. The method utilizes K2CO3 in CH3CN without any oxidants, transition metals, or additives, enabling the tunable synthesis of 1,3,4-oxadiazin-5(6H)-ones, 1,3,4-oxadiazol-2(3H)-ones, and α-ketoamides under mild aerobic conditions.