| 摘要 |
<p>NEW MATERIAL:A cephalosporin derivative I or its salt (R1,2 are H, CN, etc.; R3 is H, or -OCH3; R4 is lower alkyl; n is 0, 1 or 2; the dotted line in A ring means that the bond is either double or a single bond.). EXAMPLE:7-( 1, 3-Dithiane-2-carboxamido )-3-( 1-methyltetrazol-5-ylthiomethyl )- DELTA<3>-cephem-4-carboxylic acid. USE:Antibacterial agent, additive of feed, and preservative. Effective to a wide range of pathogenic bacteria, especially to gram-negative bacteria. PROCESS:The title compound of formula I is prepared by reacting a 7-aminocephalosporin derivative of formula II with a carboxylic acid or its reactive derivative (e.g. acid halide, etc.) to afford a compound IV, and when the R5 is protecting group of the carboxylic group, eliminating the protecting group. When the carboxylic acid is used as free state, DCC is used as a condensation agent.</p> |
