“D-Glucose” phase transfer catalyzed synthesis of benzimidazolyl oxadiazole derivatives
By N. D. Mahesh Kumar and P. K. Dubey
ABSTRACT
2-(Chloromethyl)benzimidazole (1) on condensation with 2-mercapto-1,3,4-oxadiazoles (2) gave 2-[5-phenyl-1,3,4-oxadiazol-2-thiomethyl]-1H-benzimidazole (5). Alternatively, 5 could also be prepared by the treatment of o-phenylenediamine (3) with 1,3,4-oxadiazole-2-thioacetic acid (4) under Philips conditions. 5 on treatment with dialkyl sulfate in acetonitrile using D-glucose as PTC gave the corresponding N-alkylated derivative i.e. benzimidazolylalkylthiooxadiazole (7). The latter i.e. 7(a-e) could also be prepared, alternatively, by the reaction of 2-(chloromethyl)-N-methylbenzimidazole (6) with 2-mercapto-1,3,4-oxadiazoles (2). Even though, there are several other PTC’s reported in literature, for the first time we employed D-glucose as PTC because it has got characteristics similar to that of crown ethers and polyethylene glycol. Furthermore, it is readily available, reasonably cheap, non-toxic and eco-friendly in character.
Key words: Benzimidazole, 5-substituted-2-thio-1,3,4-oxadiazoles, D-glucose, phase transfer catalyst
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