Synthesis and Antimicrobial Activity Evaluation of Amide and Sulfonamide Derivatives Containing Imidazo[2,1‐b][1,3,4]thiadiazole moiety

A series of amides (19a–i) and another of sulfonamides (21a–g) containing the imidazo[2,1‐b][1,3,4]thiadiazole moiety were synthesized and evaluated for their antimicrobial activities. Most of these compounds showed good antibacterial activities (MIC = 4–64 μg/mL). Compounds 21c (MIC = 4 μg/mL) and 21g (MIC = 4 μg/mL) exhibited strongest antibacterial activities that are comparable to that of the positive control gatifloxacin, along with low cytotoxicity (as measured against human LO2 cells) and no hemolysis, even at ultra‐high concentration (200 μM). These results indicate that these compounds show promise for further development as antibacterial agents.