Heterocyclic compounds from urea derivatives. Part XXII. Thiobenzoylated carbonohydrazides and their cyclisation

Abstract

Thioaroylthioacetic acids convert carbonohydrazide successively into 1-thioaroyl- and 1,5-bis(thioaroyl)-carbono-hydrazides. 1-Phenyl- and 1-benzylidene-carbonohydrazide similarly yield 5-monothioaroyl compounds. All are readily cyclised by mineral acids to 2-aryl-5-hydroxy-1,3,4-thiadiazoles, with loss of hydrazine or its appropriate derivative, but are unaffected by alkali. The thioaroyl adducts and their stable S-alkyl derivatives undergo ring closure when treated with hydrazine to give 4-(substituted amino)-3-aryl-5-hydroxy-1,2,4-triazoles.