Synthesis of 1,2,4-triazoles, imidazoles, pyrimidines, quinazolines, 1,3,5-triazines, and 1,3-thiazines from 3-oxo-5,6-diphenyl-2,3-dihydro-pyridazine-4-carbonyl isothiocyanate

Abstract

3-Oxo-5,6-diphenyl-2,3-dihydropyridazine-4-carbonyl isothiocyanate (1) was reacted with hydrazine hydrate, or phenyl hydrazine, to give 1,2,4-triazole derivatives in a one pot-reaction. However, reaction of 1 with benzoyl hydrazine afforded thiourea derivative that was cyclised to a differently substituted 1,2,4-triazole. Ethyl glycinate reacted with isothiocyanate 1 to give an adduct that was cyclised to imidazolidine derivative. Reaction of 1 with o-aminophenol, o-phenylenediamine or o-aminothiophenol afforded benzoxazole, benzimidazole or benzothiazole derivatives respectively. Reaction of 1 with thioglycolic acid gave 1,3-thiazine derivative, however, when 1 was treated with anthranilic acid a thiourea derivative was obtained which cyclised to a quinazoline derivative. Reaction of 1 with 2-cyanoacetamide or guanidine HCl yielded pyrimidine or triazine derivatives respectively. The structures of all compounds were confirmed by their micro analytical and spectral data.