External oxidant-free electrooxidative intramolecular S-N bond formation for one-pot synthesis for 3,5-disubstituted 1,2,4-thiadiazoles

An electrochemical oxidative reaction protocol for the synthesis of 5-amino and 3,5-diamino substituted 1,2,4-thiadiazole derivatives has been developed under undivided electrolytic conditions. The newly developed one-pot methodology involves the reaction of isothiocyanates with amidines or guanidines to give the corresponding imidoyl thioureas, which are further cyclized in situ via electrooxidative intramolecular S-N bond formation to promote the final products. This protocol features a metal- and external oxidant-free approach, broad substrate scope, good functional group tolerance, excellent yields, and one-pot operation/reaction without the isolation of the intermediates.