Synthesis of 1,2,4-Triazole and 1,3,4-Thiadiazole Derivatives from Methyl 2-Methyldithiocarbazate and Heterocumulenes

All articles of this category Methyl 2-methyldithiocarbazate 1 , reacts with diarylcarbodiimides to give 4-aryl-3-arylamino-1-methyl-5-thioxo-4,5-dihydro-1 H -1,2,4-triazoles 3 . Compound 1 also reacts with isothiocyanates to give the corresponding 5-arylamino-3-methyl-2-thioxo-2,3-dihydro-1,3,4-thiadiazoles 6 . The reaction of the 3-triphenylphosphoranylidene derivative of 1 with aromatic isocyanates leads to the mesoionic anhydro-2-arylamino-4-methyl-5 -methylthio-1,3,4-thiadiazolium hydroxides 10 . Methyl 3-aminocarbonyl-2 -methyldithiocarbazates 11 , available from 1 and isocyanates, undergo ring closure on reaction with thionyl chloride to give either 1,3,4-thiadiazole derivatives 12 or 1,2,4-triazole derivatives 13 .