Synthesis and antimicrobial activity of pyrazolinone and pyrazole analogues containing quinoline moiety

A new class of quinoline derivatives containing pyrazoline-5-one and pyrazole moiety (3a-j and 4a-j) have been synthesized by condensation of various oxobutyrates/pentane-2,4-dione derivatives with 8-quinolinoxyacetic acid hydrazide. Elemental analysis, IR, 1 H NMR and mass spectral data support the structures of the newly synthesized compounds. The synthesized compounds have been evaluated for their antimicrobial activity against S. aureus, E. coli, A. niger and C. albicans using serial plate dilution method. Compound 4-(2-(4-fluorophenyl)hydrazono)-3-methyl-1-(2-(quinolin-8-yloxy) acetyl)-1H-pyrazol-5(4H)-one 3f having log P 1.52 has emerged as the most potent antimicrobial agent of the series.