Heterocyclic compounds from urea derivatives. Part IX. Addition products of diaminoguanidine and isothiocyanate esters, and their cyclisation

Abstract

NN′-Diaminoguanidine reacts with equimolar proportions of aromatic isothiocyanates in dimethylformamide at 100° affording moderate yields of 4-aryl-3-hydrazino-5-mercapto-1,2,4-triazoles as main products, together with smaller quantities of the corresponding 3-amino-analogues. The use of an excess of isothiocyanate produces 1-(3-mercapto-4-phenyl-1,2,4-triazol-5-yl)-4-phenyl-3-thiosemicarbazide, also obtained as a minor product under standard conditions.

The structure of the 4-aryl-3-hydrazino-5-mercapto-1,2,4-triazoles is based on typical reactions of their functional groups and is confirmed by the degradation of the 4-phenyl compound to authentic 3-mercapto-4-phenyl-1,2,4-triazole.