Synthesis and antimicrobial activity of some new thiazole, thiophene and pyrazole derivatives containing benzothiazole moiety

In an attempt to find a new class of antimicrobial agents, a series of thiazole, thiophene, pyrazole and other related products containing benzothiazole moiety were prepared via the reaction of N-(benzothiazol-2-yl)-2-cyanoacetamide (1) with appropriate chemical reagents. These compounds were screened for their antibacterial activity against Gram-positive bacteria (Staphylococcus aureus and Streptococcus pyogenes), Gram-negative bacteria (Pseudomonas phaseolicola and Pseudomonas fluorescens) and antifungal activity against Fusarium oxysporum and Aspergillus fumigatus. Among the synthesized compounds, thiophene 13 showed equal activity with chloroamphenicol against S. aureus (MIC 3.125 μg/mL), while its activity was 50% lower than of chloroamphenicol against S. pyogenes. Thiazole 3 and pyrazolo[1,5-a]pyrimidine 21b were found to exhibit the most potent in vitro antifungal activity with MICs (6.25 μg/mL) against A. fumigatus and F. oxysporum. Structures of the newly synthesized compounds were established by elemental analysis and spectral data.