A Versatile Approach for the Synthesis, Characterization, and Bioassay of Novel 3-(1-Acetyl-5-substituted phenyl-4, 5-dihydro-1 H -pyrazol-3-yl)-4-hydroxy-1-methyl/phenylquinolin-2(1 H )-one Derivatives

A series of novel 3-(1-acetyl-5-substitutedphenyl-1 H -pyrazol-3-yl)-4-hydroxy-1-methylquinolin-2(1 H )-ones ( Va–Vf ) and 3-(1-acetyl-5-substitutedphenyl-1 H -pyrazol-3-yl)-4-hydroxy-1-phenylquinolin-2(1 H )-ones ( Vg–Vl ) were designed and synthesized by the condensation of hydrazine hydrate with ( E )-3-(3-(substituted phenyl)acryloyl)-4-hydroxy-1-methyllquinolin-2(1 H )-one ( IVa–IVf ) and ( E )-3-(3-(substituted phenyl)acryloyl)-4-hydroxy-1-phenylquinolin-2(1 H )-one ( IVg–IVl ) and these intermediates are prepared from 3-acetyl-4-hydroxy-1-methylquinolin-2(1 H )-one ( Ia ) and 3-acetyl-4-hydroxy-1-phenylquinolin-2(1 H )-one ( IIa ) with diversely functionalized aldehydes ( IIIa–IIIf ). This synthetic approach provides a new and efficient tool for constructing novel heterocycles on newly synthesized substituted α,β-unsaturated carbonyl compounds. The structures of all the synthesized products were confirmed with their elemental analysis, 1 H NMR, 13 C NMR, IR, and MS analysis. Further, the newly synthesized compounds were screened for in vitro antibacterial activity against G+ bacteria ( S. aureus and B. subtili) , G– bacteria ( P. aeruginosa and C. albicans) , antifungal activity against ( C. albicans and A. niger) by using agar well diffusion method. Ciprofloxacin was used as a standard reference drug for antibacterial and Fluconazole drug was used for antifungal activity. The study reveals that the compounds ( Ve ), ( Vf ), ( Vi ), ( Vk ), and ( Vl ) showed potential activity against G+ bacteria, and compounds ( Vc ), ( Ve ), ( Vi ), ( Vk ), and ( Vl ) showed significant activity against G– bacteria. Compounds ( Va ), ( Vc ), ( Ve ), ( Vf ), ( Vh ), ( Vi ), ( Vk ), and ( Vl ) exhibited excellent potential against the antifungal activity.