Synthesis and antimicrobial activity of substituted benzimidazole, benzothiazole and imidazole derivatives.

New benzimidazole, benzothiazole and imidazole derivatives were synthesized by reacting electron-rich olefins (5, 23 and 29) with appropriate reagents. The compounds synthesized were identified by 1H, 13C-NMR, FT-IR and mass spectroscopic techniques and micro analysis. All new and related compounds were evaluated for their in vitro antimicrobial activity against different bacteria. The compounds 17, 18, 19, 20, 21, 22 and 24 were found very effective to inhibit the growth of Enterococcus faecalis (ATCC 29212) and Staphylococcus aureus (ATCC 29213) at minimum inhibitory concentrations (MICs) of 25, 25, 12.5, 50, 25, 50 and 50 micrograms/ml, respectively. The compounds 4, 10a, 10c, 16, 25, 26 and 31 were significantly effective against Enterococcus faecalis (ATCC 29212) and Staphylococcus aureus (ATCC 29213) with MIC values of 100-200 micrograms/ml. None of the compounds proved to be effective against Escherichia coli (ATCC 25922) and Pseudomonas aeruginosa (ATCC 27853) in the concentrations studied.