Amidrazones. 6. Synthesis of 1,2,4‐thiadiazoles by thermolysis of N3‐thiocarbamoylamidrazone ylides

Reaction of N3‐unsubstituted amidrazone ylides (1a and 1b) with alkyl or aryl isothiocyanates gives N3‐thiocarbamoylamidrazone ylides (2). Thermolysis of 2 gives 3‐alkyl(or aryl)‐5‐alkyl(or aryl)amino‐1,2,4‐thiadiazoles (3a‐i).