[3 + 2]-Cycloaddition of 2 H-Azirines with Nitrosoarenes: Visible-Light-Promoted Synthesis of 2,5-Dihydro-1,2,4-oxadiazoles.

A formal [3 + 2]-cycloaddition reaction of 2 H-azirines with nitrosoarenes has been achieved under irradiation by visible light with the assistance of organic dye photoredox catalyst. This method utilizes nitrosoarenes as efficient radical acceptors and provides a green and powerful method for a series of biologically important 1,2,4-oxadiazole derivatives in moderate to good yields.