Synthesis and biological activity of fluorinated 2-amino-4-aryl-3,4-dihydro[1,3,5]triazino[1,2-a]benzimidazoles

The heterocyclic nucleus s-triazino[1,2-a]benzimidazole has been reported to exhibit antibacterial activity. In this study, seven new 3,4-dihydro[1,3,5]triazino[1,2-a]benzimidazole derivatives were prepared via cyclocondensation between 2-guanidinobenzimidazole and fluorine substituted (including trifluoromethyl) benzaldehydes. The structures of all the compounds were confirmed by 1H, 13C NMR and IR spectral data. Spectral data also suggested the existence of various tautomeric forms of the fluorine-containing s-triazino[1,2-a]benzimidazole compounds. The synthesized compounds were also screened for antibacterial and bovine dihydrofolate reductase (DHFR) inhibitory activities. The compound 3g substituted with a 3′,5′-bis(trifluoromethyl)phenyl moiety demonstrated the best antibacterial activity in the series. None of the tested compounds significantly inhibited bovine DHFR.