Synthesis of certain sulfones, sulfanilamides and sulfonamides of pyrazolo [5,4-b] imidazo [2,1-b] thiazole with antibacterial activity

6-phenylimidazo [2, 1-b] thiazole-3-N, N-dimethylacetamide [I] was formulated using Vielsmeier reagent to afford the corresponding 5-formyl derivative [II]. Treatment of II with benzenediazonium chloride gave 5-formyl-6-phenylimidazo [2, 1-b] thiazole-3-[N, N- dimethyl-1-phenylazo] acetamide [III]. Cyclization of III using FeCl3 and DMSO or by heating in nitrobenzene afforded the corresponding new fused system, 3-N, N-dimethylacarbamoyl-1, 6-diphenylpyrazolo [5, 4-b] imidazo [2, 1-b] thiazole-5-carboxaldehyde [IV]. The aldehydic function in IV was converted into substituted sulfones, sulfanilamides and sulfonamides and the antibacterial activity of the newly prepared compounds was evaluated