Condensation and Cyclization of 2-Hydrazinobenzimidazole, -benzoxazole, and -benzothiazole

Article abstract of DOI:10.1246/bcsj.61.1339

2-Hydrazinobenzoxazole (1), -benzimidazole (2), and -benzothiazole (3) were condensed with ethyl chloroformate and/or diethyl oxalate to produce 1,2,4-triazolo- and 1,2,4-triazino-fused ketones of the title azoles respectively.Condensation of 1 and 2 with aromatic aldehydes and/or acetic anhydride produced, 3-aryl- and 3-methyl-substituted 1,2,4-triazolo-fused azoles respectively.The hydrazines 1 and 2 cyclized with acetylacetone to produce the corresponding 2-(1-pyrazolyl) derivatives. 2-Acetylthiazolobenzimidazole reacted with hydroxylamine and/or alkylamines, to produce the corresponding condensation products.Also, it condensed with aromatic aldehydes to give the chalcones.When reacted with benzenediazonium salt, it gave the corresponding 2-arylazo-substituted compounds.