Design, Synthesis and Biological Evaluation of Novel Substituted Imidazo[2,1-a] Isoindole 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 CDI using one pot Pd-catalyzed C-C bond coupling. The reaction of imidazo[2,1-a]isoindol-5-one (2a-d) with substituted α-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 IR, ¹H NMR, ¹³C 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 possessing an excellent broad spectrum of inhibiting potency against all the tested bacterial strains with MIC values ranging from 3.125-25 μgmL^−1.