Studies on Pyridonecarboxylic Acids. IV. Synthesis and Antibacterial Activity Evaluation of S-(-)- and R-(+)-6-Fluoro-1-methyl-4-oxo-7-(1-piperazinyl)-4H-[1, 3]thiazeto[3, 2-a]quinoline-3-carboxylic Acids

Optically active isomers of 6-fluoro-1-methyl-4-oxo-7-(1-piperazinyl)-4H-[1, 3]thiazeto[3, 2-a]quinoline-3-carboxylic acid (NM394, 3) were prepared through optical resolution of their racemic intermediate (±)-1 by high-performance liquid chromatography (HPLC). The absolute configuration at the C-1 position in the thiazetoquinolone ring of (-)-3 was confirmed by X-ray analysis of (-)-4 to be S. The in vitro antibacterial activity of (-)-3 was 2-8 times that of (+)-3.