Synthesis and Antimicrobial Evaluation of Novel Pyrazolo[1,5-a]pyrimidine, Pyrimido[1,2-a]benzimidazole, Triazolo[4,3-a]pyrimidine and Pyrido[1,2-a]benzimidazole Derivatives Incorporated Phenylsulfonyl Moiety

Phenylsulfonylacetonitrile (1) reacts with dimethylformamide dimethyl acetal (DMF-DMA) to afford 3-(dimethylamino)-2-(phenylsulfonyl)acrylonitrile (2). Enaminonitrile 2 reacts with 5-aminopyrazole derivatives 3a-e, 5-amino-l,2,4-triazole (7) and 2-aminobenzimidazole (11) to afford new pyrazolo[1,5-a]pyrimidine, triazolo[4,3-a]pyrimidine and pyrimido[1,2-a]benzimidazole derivatives 4a-e, 9 and 12, respectively. Also, 3-(dimethylamino)-2-(phenylsulfonyl)acrylonitrile (2) reacts with 2-(1H-benzimidazol-2-yl)acetonitrile (13) to give the corresponding pyrido[1,2-a]benzimidazole derivative 15. Some of the newly synthesized compounds were tested in vitro for their antibacterial and antifungal activities, and showed promising results.