Synthesis, physicochemical properties and antimicrobial activity of some new benzimidazole derivatives

Some derivatives of benzimidazole were synthesized by nucleophilic substitution of 2-substituted-1H-benzimidazole. The resulting ethyl (2-substituted-1H-benzimidazol-1-yl) acetate on treatment with hydrazine hydrate yielded 2-(2-substituted-1H-benzimidazol-1-yl) acetohydrazide, which on further reaction with one equivalent of different aliphatic or aromatic carboxylic acids in the presence of phosphoryl chloride afforded the corresponding target compounds, 2-substituted-1-[{(5-substituted alkyl/aryl)-1,3,4-oxadiazol-2-yl} methyl]-1H-benzimidazole. The structures of the synthesized compounds were evaluated by spectral and elemental methods of analyses. All the synthesized compounds were screened for their antimicrobial activities. All of the derivatives showed good activity towards Gram-positive bacteria and negligible activity towards Gram-negative bacteria. Some of the synthesized compounds showed moderate activity against tested fungi.