A metal-free and mild approach to 1,3,4-oxadiazol-2(3H)-ones via oxidative C-C bond cleavage using molecular oxygenElectronic supplementary information (ESI) available: Experimental procedures, new compound characterization data, NMR spectra of products, and supporting figures. CCDC 1538325 and 1538326. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7ob03188b

A mild metal-free approach to 1,3,4-oxadiazol-2(3 H )-ones via 1,3,4-oxadiazin-5(6 H )-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 K 2 CO 3 in CH 3 CN without any oxidants, transition metals, or additives, enabling the tunable synthesis of 1,3,4-oxadiazin-5(6 H )-ones, 1,3,4-oxadiazol-2(3 H )-ones, and α-ketoamides under mild aerobic conditions. A metal-free aerobic oxidative C-C bond cleavage reaction for the synthesis of 1,3,4-oxadiazol-2(3 H )-ones is described.