Synthesis and antibacterial activity of some 3-(5-aryl-4H-pyrazol-3-yl) anthracen-10(9H)-ones

A series of 3-(5-aryl-4 H-pyrazol-3-yl)anthracen-10(9 H)-ones were synthesized from anthracen-10(9 H)-one (1) and studied for their in vitro antibacterial activity. Anthracen- 10(9 H)-one after Friedel crafts acetylation with acetyl chloride yielded 3-acetylanthracen- 10(9 H)-one (2) which on further reaction with substituted aromati c aldehydes in the presence of catalytic amount of sodium hydroxid e in water and ethanol furnished the corresponding 3-(3-arylacryloyl)anthracen-10(9 H)-ones (3a-g) as intermediate compounds, which on further reaction with hydrazine hydrate in absolute ethanol formed the title compounds 3-(5-aryl-4H-pyrazol-3-yl)anthracen-10(9 H)-ones (4a-g). These compounds were characterized by elemental analysis, IR, Mass and 1 H-NMR spectral data. All the compounds were evaluated for their in vitro antibacterial activity against two gram positive s trains (Bacillus subtilis and Staphylococcus aureus ) and two gram negative strains ( Escherichia coli and Pseudomonas aeruginosa ) taking ciprofloxacin as a standard drug. Some of the compounds showed significant antibacterial activity .