Synthesis, and antibacterial activities of novel 1,3,4a,9-tetraza-4H-fluoren-2-amines incorporating phenoxy-N-arylacetamide, pyrazole, and 2-(4-(1-phenyl-1H-pyrazol-3-yl)phenoxy)-N-arylacetamide moieties

A ring annelation reaction was used to successfully prepare benzo[4,5]imidazo[1,2-a][1,3,5]triazines (Systematic Name: 1,3,4a,9-tetraza-4H-fluoren-2-amines) tethered to phenoxy-N-arylacetamide, pyrazole, and 2-(4-(1-phenyl-1H-pyrazol-3-yl)phenoxy)-N-arylacetamide moieties utilizing 1-(1H-benzo[d]imidazol-2-yl)guanidine and the proper aldehydes as precursors. 2-(Phenylamino)ethyl fragment of compound 7 was cleaved off and compound 8 was formed. The constitutions of the novel compounds were confirmed based on spectral data. The antibacterial activity was evaluated for the prepared compounds against two gram-negative and two gram-positive bacteria. Among them, compound 12b (inhibition zone 16 ± 0.7 mm) was the most promising against S. aureus compared to Gentamycin (15 ± 0 mm). Also, compounds 5a and 5d exerted comparable antibacterial activity (inhibition zones 13 ± 1.4 and 13 ± 2.1 mm), respectively to Gentamycin against S. aureus. Minimum inhibitory concentration (MIC) evaluation against S. aureus showed that compound 12b had the lowest MIC value (78.1 µg/mL).