Synthesis, structure and antibacterial activity of novel 1-(5-substituted-3-substituted-4,5-dihydropyrazol-1-yl)ethanone oxime ester derivatives.

A series of novel 1-(5-substituted-3-substituted-4,5-dihydropyrazol-1-yl)ethanone oxime ester derivatives are synthesized. The results show that compounds 14 and 26c can strongly inhibit Staphylococcus aureus DNA gyrase and Escherichia coli DNA gyrase (with IC(50) of 0.25 and 0.125 microg/mL against S. aureus DNA gyrase, 0.125 and 0.25 microg/mL against E. coli DNA gyrase). On the basis of the biological results, structure-activity relationships are also discussed.