The Synthesis of 3,5‐Diamino‐1,2,4‐oxadiazoles. 1st Communication

Reaction of the 1‐substituted‐3‐cyano‐isothioureas 6 with hydroxylamine gave mixtures of the 5‐amino‐3‐substituted‐amino‐1,2,4‐oxadiazoles 1 and the isomeric 3‐amino‐5‐substituted‐amino‐1,2,4‐oxadiazoles 8 in which 1 usually predominated. The structural assignment of these products is discussed. In a second method, the 2‐hydroxy‐1‐methyl‐1‐phenyl‐guanidine 15 was converted to the corresponding 3‐disubstituted‐amino‐5‐trichloromethyl‐1,2,4‐oxadiazole 16, a precursor to the 5‐amino derivatives 17 by nucleophilic displacement of the trichloromethyl group.