title: Semisynthetic beta-lactam antibiotics. VI. Synthesis and antimicrobial activity of alpha-hydrazonobenzylcephalosporins.
abstract: Using as a model cephalosporins with an alpha-hydroxyimino moiety in the side chain, some new (E)-alpha-hydrazono and alpha-methylhydrazono benzyl cephalosporins were prepared. While the synthesis of methylhydrazono-derivatives (I a-d) involved direct condensation of the methylhydrazionacid (II a-b) with a protected 7-aminocephalosporanic derivative, the N-unsubstituted compounds (I e-f) had to be prepared from the N-acyl protected hydrazono acids (III a-d). The cephalosporin (I f) was also obtained as Z-isomer by condensation of the corresponding alpha-oxo compound with 4-nitrobenzyloxycarbonylhydrazine, chromatographic separation of the obtained E-Z mixture, and hydrogenolysis of the Z form. The in vitro antibacterial evaluation showed that N-methyl substitution is favorable among the E compounds, whereas among the N-unsubstituted hydrazono derivatives, the compound Z-(I f), although less stable, is much more potent than the corresponding E-isomer.
mesh_terms: D001419:Bacteria / Q000187:drug effects*; D002511:Cephalosporins / Q000138:chemical synthesis* / Q000494:pharmacology; D055598:Chemical Phenomena; D002621:Chemistry; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D008826:Microbial Sensitivity Tests
chemical_list: D002511:Cephalosporins