Background: Reaction of α,β-unsaturated ketones with o-phenylenediamine afforded corresponding
Objective: α,β-Unsaturated ketones of 6-acetyl-5-hydroxy-4-methylcoumarin are precursors for synthesis of
2,3-dihydro-1H-1,5-benzodiazepines by a reaction with o-phenylenediamine.
Methods: Enones of 6-acetyl-5-hydroxy-4-methylcoumarin were prepared from this ketone and (un)substituted
benzaldehydes in the presence of piperidine, triethylamine, or pyridine as a catalyst in absolute ethanol with
1:1 molar ratios, respectively. 2',3'-Dihydro-1H-1',5'-benzodiazepines were synthesized by using the reaction
of these enones with o-phenylenediamine in absolute ethanol in the presence of glacial acetic acid as a catalyst.
Their biological activities were evaluated using the disk diffusion method.
Results: Seven new 2',3'-dihydro-1H-1',5'-benzodiazepines were obtained and their structures were confirmed
by thin-layer chromatography, IR, NMR and MS spectra. Some synthesized benzodiazepines showed antibacterial
and antifungal activities against Escherichia coli (Gram-(−) bacterium), Staphylococus epidermidis
(Gram-(+) bacterium). Candida albicans (fungus).
Conclusion: The formation of enones from 6-acetyl-5-hydroxy-4-methylcoumarin and (un)substituted benzaldehydes
could be catalyzed by piperidine, triethylamine, pyridine to afford similar yields. 2',3'-dihydro-1H-
1',5'-benzodiazepines have been synthesized from the aforementioned enones and o-phenylenediamine.