Synthesis and characterization of some ethoxyphthalimide substituted triazole derivatives assembled with benzimidazole and thiazolidinone heterocycles

Some alkoxyphthalimide derivatized2-(2-(5-((2-methyl-1H-benzimidazol-1-yl)methyl)-4-(4-oxo-2-substituted phenylthiazolidin-3-yl)-4H-1,2,4-triazol-3-ylthio) ethoxy)isoindoline-1,3-diones (8a-d) have been synthesized by multistep reaction sequence. Ethyl-2-(2-methyl-1H-benzimidazol-1-yl)-acetate (1) prepared by condensation of 2-methyl benzimidazole with ethylchloroacetate was treated with hydrazine hydrate to obtain 2-(1H-benzoimidazol-1-yl)acetohydrazide (2). Alkali induced cyclisation of (2) with CS2 gave 1,3,4-oxadiazolethione derivative (3). Replacement of ring oxygen with nitrogen to convert (3) into a triazole derivative was carried out by condensing with hydrazine hydrate. Schiff's base derivatives (6a-d) were obtained by nuleophilic addition cum elimination reaction of amino group of (4) with various araldehydes (5a-d). Condensative cyclisation of benzimidazolylthioxotrizoles with thiolacetic acid in ZnCl2/DMF gave corresponding phenyl thiazolidinone derivatives (7a-d). Thiol form of triazolethiones was finally condensed with phthalimidoxyethyl bromide to synthesize targeted products (8a-d). Structures of synthesized compounds were confirmed by spectral studies (IR, H-1 NMR, Mass), elemental analysis and chemical tests.