Synthesis and antibacterial activity of a novel series of 2,3-diaryl-substituted-imidazo(2,1-b)-benzothiazole derivatives.

Benzothiazole and imidazole compounds are extensively studied heterocyclics due to their wide spectrum of bioactivities. Among them, the imidazo(2,1-b)-benzothiazole derivatives are pharmacologically important because of their immunostimulant, anti-inflammatory, antifungal, antimicrobial, antitumor, and other activities. In the present research work, a novel series of 2,3-diaryl-substituted imidazo(2,1-b)-benzothiazoles 13a-o have been synthesized by reaction of substituted 2-aminobenzothiazoles 1-8 and an appropriately substituted alpha-bromo-1-(4''-substituted)-phenyl-2-(4'-substituted)-phenyl-1-ethanones 9-12 in the presence of anhydrous acetonitrile. They were characterized by physicochemical, elemental, and spectral (IR, (1)H-NMR, and Mass) data. All the synthesized compounds were screened for their in-vitro antibacterial activity against Gram-positive, Gram-negative bacteria. The investigation of antibacterial screening data revealed that most of the compounds tested have demonstrated congruent activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa as compared with the standard ampicillin. Among the series, compounds 13d, 13h, and 13m exhibited excellent an antibacterial activity profile as compared with the standard. In summary, preliminary results indicate that some of the newly synthesized title compounds exhibited promising antibacterial activities and they warrant more consideration as prospective antimicrobials.