Copper-catalyzed synthesis of 3-substituted-5-amino-1,2,4-thiadiazoles via intramolecular N-S bond formation

A copper-catalyzed N-S bond formation was utilized to produce 3-substituted-5-amino-1,2,4-thiadiazoles from imidoyl thioureas obtained by reaction of amidine hydrochlorides with isothiocyanates. Moreover, the 1,2,4-thiadiazoles were generated through a one-pot protocol without the isolation of the intermediates. This new method is highly efficient and convenient because it employs the cheap and environmentally friendly copper salt and can be conducted under air.