Synthesis of novel 3-(5-sulfanyl-1,3,4-oxadiazol-2-yl)-2H-chromen-2-one condensed s -triazinyl piperazines and piperidines as antimicrobial agents

Synthesis and antimicrobial activity of a new series of 3-(5-sulfanyl-1,3,4-oxadiazol-2-yl)-2H-chromen-2-ones based on various substituted piperazines and piperidines incorporating a 1,3,5-triazine moiety are reported in this article. 3-{5-[(4,6-dichloro-1,3,5-triazin-2-yl)sulfanyl]-1,3,4-oxadiazol-2-yl}-2H-chromen-2-one 3 was obtained by the reaction of 2,4,6-trichloro-1,3,5-triazine 1 with 3-(5-sulfanyl-1,3,4-oxadiazol-2-yl)-2H-chromen-2-one 2 which was obtained by following the method reported in the literature. Intermediate 3 was then condensed with 8-hydroxyquinoline 4 to form 3-(5-{[4-chloro-6-(quinolin-4-yloxy)-1,3,5-triazin-2-yl]sulfanyl}-1,3,4-oxadiazol-2-yl)-2H-chromen-2-one 5. This was further treated with various substituted piperazines and piperidines to obtain the title compounds 7a–u, which were then subjected to determine their in vitro biological efficacy against bacterial and fungal strains as two Gram-positive bacteria (S. aureus, B. cereus), six Gram-negative bacteria (E. coli, P. aeruginosa, K. pneumoniae, S. typhi, P. vulgaris, and S. flexneria) and two fungal species (A. niger, and C. albicans) with an intent to develop novel class of antimicrobial agents. The results indicate that some of the novel s-triazines have noteworthy activity in MIC (μg/ml) and zone of inhibition (mm) indicating potential leads for further drug discovery study. All the final compounds were structurally elucidated on the basis of IR, 1H NMR, 13C NMR, 19F NMR spectroscopy, and elemental analysis.