Synthesis of Mesoionic 1-aryl-4-(phenyl/p-chlorophenyl)imidazo[2,1-b]thiazol-4-ones and Study of their Monoamine Oxidase, Succinate Dehydrogenase Inhibitory, Anti-convulsant, and Antibacterial Activity

1-Aryl-2-mercapto-4-(phenyl/p-chlorophenyl)imidazoles (Ia-j) were condensed with monochloroacetic acid to give 1-aryl-4-(phenyl/p-chlorophenyl)imidazo-2-mercaptoacetic acid (IIa-j). These acids were subsequently cyclized with an acetic anhydride-pyridine mixture to give a new fused ring mesoionic 1-aryl-4-(phenyl/p-chlorophenyl)imidazo[2,1-b]thiazol-1-3-ones (IIIa-j). These compounds possess AID50 values ranging from 500 to 1000 mg kg-1, inhibit monoamineoxidase (32-68%), and succinate dehydrogenase (28-55%) in vitro at a concentration of 2×10-4 M, and provide 20-60% protection against pentylenetetrazole induced convulsions in mice.