Synthesis of Novel 1,3-thiazole-, 1,2,4-triazole- thione and Triazepine Derivatives

Abstract

Reaction of the cyanoacetic hydrazide derivatives 1a–e with isothiocyanates gave the hydrazinocarboxamide and thioamide derivatives 2a–g and 1,2,4-triazole-3-thiones 3. Upon reacting 1b–d with ethyl bromoacetate followed by isothiocyanates; the 1,3-thiazole-5-carbohydrazides 5 were afforded. Cyclisation of products 1b–e with triethylorthoformate furnished the unexpected ethyl cyanoacetylhydrazonoformate 6; rather than the expected triazolethiones of type 7. A mechanism for the formation of product 6 was suggested and discussed. Upon heating product 6 with some arylamines in acetonitrile, the 5-aminotriazepin-7-ones 9 were afforded.