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-alpha] 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 thiazeto-quinolone ring of ( - )-3 was confirmed by X-ray analysis ( - )-4 to be S. The in vitro antibacterial activity of ( - )-3 was 2--8 times that of (+)-3.