An effective and expeditious approach for the construction of biologically important 5-guanidino-1,2,4-thiadiazole and 1,2,4-triazolo[1,5-a]pyridine derivatives has been developed. This new protocol involves the phenyliodine(III) diacetate [PhI(OAc)2]-mediated oxidative cyclization of thioureas/2-aminopyridines and imidates via N–S and N–N bond formation at ambient temperature. This method furnishes the versatile 5-guanidino-1,2,4-thiadiazoles and 1,2,4-triazolo[1,5-a]pyridines in a scalable manner with high efficiency and excellent regioselectivity.
