Aerobic radical-cascade cycloaddition of isocyanides, selenium and imidamides: facile access to 1,2,4-selenadiazoles under metal-free conditions

A novel and facile metal-free method for the green synthesis of 1,2,4-selenadiazol-5-amine derivatives through the aerobic radical-cascade multi-component reactions of isocyanides, selenium powder and imidamides is reported herein. O2 in the air was employed as the green oxidant to achieve the cycloaddition with the generation of H2O as the sole by-product. It also features good functional group compatibility and broad substrate scope. In addition, this method was successfully applied to the functionalization of biologically active molecules.