Construction of the 1,3,4-Oxadiazole Rings at C-5 of Benzotriazole and Investigation of Its Biological Activities

Abstract

This study reports the synthesis of novel benzotriazole-substituted 1,3,4-oxadiazole rings  4-17 through a four-step reaction sequence. Initially, benzotriazole-5-carboxylic acid (1) was converted to its acid chloride derivative 2 via treatment with thionyl chloride. Subsequently, nucleophilic addition of hydrazine hydrate yielded 89% of hydrazide 3. The desired compounds 4-17 were then obtained via condensation of compound 3 with different aromatic aldehydes, followed by an oxidative cyclization reaction using I₂/K₂CO₃. The target compounds 4-17 were obtained in yields ranging from 65 to 90%. The structures were confirmed using FT-IR and ¹H NMR spectroscopy. Additionally, the antioxidant and antibacterial properties of a few of these products were investigated.