| 摘要 |
<p>Cephalosporins of formula <IMAGE> wherein -A- represents a group of the formula, -CH2- or a group of the formula, <IMAGE> in which R<18> represents a hydrogen atom or a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aralkyl, aryl, heterocyclic group or a hydroxyl-protecting group or a group of the formula, <IMAGE> (each of R<19> and R<20>, which may be the same or different, represents a hydroxyl, alkyl, aralkyl, aryl, alkoxy, aralkyloxy or aryloxy group), and the bond @ means that the compound may be a syn-isomer or an anti-isomer or a mixture thereof; R<1> is H or carboxyl-protecting group; R<2> is a substituted or unsubstituted 2,3- dioxo-1,2,3,4-tetrahydropyrazinyl, 2-oxo-1,2-dihydropyrazinyl, 3,6-dioxo- 1,2,3,6-tetrahydropyridazinyl or 6-oxo-1,6-dihydropyridazinyl group; R<3> is H or alkoxy; R<4> represents a hydrogen atom or a halogen atom; and R<5> represents a hydrogen atom or a protected or unprotected amino group. These cephalosporins have a broad antibacterial spectrum, are stable against beta -lactamase produced by bacteria, have a low toxicity, and are well absorbed when administered orally or parenterally. Intermediates of formula: <IMAGE> where R<1> to R<3> are as above and R<28> is amino are also disclosed.</p> |
