Synthesis and Structure-Activity Relationships of 5-Substituted 6,8-Difluoroquinolones, Including Sparfloxacin, a New Quinolone Antibacterial Agent with Improved Potency

Article abstract of DOI:10.1021/jm00168a018

A series of 5,7-disubstituted 1-cyclopropyl-6,8-difluoro-4(1H)-oxoquinoline-3-carboxylic acids (10-36) were prepared; the C-5 substituent in these compounds comprised halo, hydroxy, mercapto, and amino groups and the C-7 functional group included variously substituted piperazines.In vitro antibacterial screening results indicated that the amino group was optimal among the C-5 substituents.A combination of the C-5 amino group and the C-7 3,5-dimethylpiperazinyl appendage in this series conferred the best overall antibacterial property with lack of adverse drug interactions.Compound 36k was superior to ciprofloxacin in both in vitro and in vivo potency and hence was selected as a promising candidate for an improved therapeutic agent.