Heterocyclic compounds from urea derivatives. Part XXI. Adducts from thiocarbonohydrazides and aroyl isothiocyanates and their cyclisation

Abstract

Thiocarbonohydrazide is converted into 1-aminothiocarbamoyl-4-aroyl-3-thiosemicarbazides or 1,5-bis(aroyl-thiocarbamoyl)thiocarbonohydrazides by the addition of one or two moles of aroyl isothiocyanate, respectively. 1-Phenyl- or 1-benzylidene-thiocarbonohydrazide and aroyl isothiocyanates yield the appropriate mono-adducts analogously. 1-Aminothiocarbamoyl-4-benzoyl-3-thiosemicarbazide, the simplest representative of these classes of compounds, is cyclised to 3-mercapto-5-phenyl-1,2,4-triazole in alkaline, and to 2-benzamido-5-mercapto-1,3,4-thiadiazole in acid media; the action of alkyl halides in the appropriate alcohol yields 2-benzamido-5-alkylthio-1,3,4-thiadiazoles. The other types of mono- and di-adducts behave similarly. Acidified hydrogen peroxide cyclises and oxidises 1-anilinothiocarbamoyl-4-benzoyl-3-thiosemicarbazide to 2-benzamido-5-phenylazo-1,3,4-thiadiazole.