Synthesis of functionalized dihydroimidazo[1,2-A]pyridines and 4-thiazolidinone derivatives from maleimide, as new class of antimicrobial agents

New dihydroimidazo[1,2-a]pyridines and 4-thiazolidinone derivatives have been synthesized by condensation reaction of substituted maleimide with 2,3-diaminopyridine or thiosemicarbazone under neutral or acidic medium in low and good yields. Structures and purity of these new products were confirmed by HRMS, 1H, 13C NMR, IR spectroscopy and crystal X-ray analysis. Optimization of reaction conditions for the preparation of dihydroimidazo[1,2-a]pyridine was studied by using a Keggin-type heteropolyacid catalyst. All the synthesized compounds were evaluated in vitro for their antibacterial and antifungal activities against six pathogenic bacteria and a strain of yeast. Compounds 4d, 7b, and 7d were more potent than the reference drug, against Candida albicans IPA (200). Compounds 4a, 4b, 7a, and 7b possessed the highest inhibitory effect or bactericidal activity against SARM.