Design, synthesis, and biological evaluation of novel substituted imidazo[2,1-αisoindole derivatives as antibacterial agents

An efficient protocol has been developed for the synthesis of fused imidazo[2,1-a]isoindol-5-ones (2a-d) from 2-iodo benzoic acids and N,N-carbonyldiimidazole (CDI) using one-pot Pd-catalyzed CC bond coupling. The reaction of imidazo[2,1-a]isoindol-5-one (2a-d) with substituted -bromo ketones in toluene afforded corresponding imidazo[2,1-a]isoindolium derivatives (3a-i) in good yields. The structures of the title compounds were well established on the basis of infrared (IR), H-1 NMR, carbon-13 nuclear magnetic resonance (C-13 NMR), mass spectral data, and elemental analysis (C, H, and N). In vitro antibacterial results revealed that, the compounds 3b and 3i were found to possess an excellent broad spectrum of inhibiting potency against all the tested bacterial strains with minimum inhibitory concentration values ranging from 3.125 to 25 mu g mL(-1).