Synthesis and activity of potent 3-(isoxazolidin-5-yl)- and 3-(isoxazolidinium-5-yl)cephalosporins.

The syntheses and in vitro antibacterial activities of 3-(isoxazolidin-5-yl)- and 3-(isoxazolidinium-5-yl)cephalosporins are described. 1,3-Dipolar cycloaddition of 3-vinylcephalosporin with nitrone gave diastereomeric isomers of 3-(isoxazolidin-5-yl)cephalosporin. The antibacterial activities of 3'-(S)-isomers were superior to those of 3'-(R)-isomers. The quaternarization of isoxazolidine ring increased the antibacterial activity. Among them, compound 10b with a hydroxyimino group in the C-7 side chain showed potent activities against staphylococci and compound 10f with an N-hydroxypyridone exhibited an excellent antipseudomonal activity.