Synthesis and Antimicrobial Activities of Some New Heterocyclic Derivatives from 4-Hydroxy-6-methylquinoline-3-carbaldehyde

Treatment of starting quinoline-3-carbaldehyde 1 with acetophenones 2a-d gave the chalcone 3. The latter compounds, on cyclization, gave the pyrazoloquinolinol derivatives 4a-d after their treatment with benzohydrazide. Quinoline-3-carbaldehyde (1) reacted with cyclohexane-1,3-dione and either malononitrils (6a) or ethyl cyanoacetate (6b) in ethanol containing a catalytic amount of trimethylamine to give the chromenopyranoquinoline derivatives 8. The condensation of 8 with hydrazine derivatives afforded the hydrazines 10a, and b. Also, hydrazones gave the corresponding arylidines 12a, and b on treatment with aldehydes 11. The antibacterial activity of the synthesized compounds was tested against four different bacterial species. The tested compounds showed moderate to potent antibacterial activity.