| 摘要 |
<p>3-Methylenecepham-4-carboxylic acids and esters of the Formula I and 3-methyl- DELTA 3-cephem-4-carboxylic acids and esters of the Formula II where R is hydrogen or an organic acyl group and R1 is hydrogen, C1-C4 alkyl a carboxylic acid protecting group or a pharmaceutically acceptable cation are prepared via the reductive displacement of a 3-substituted methyl cephalosporin of the Formula III where R2 is an organic residue such that -SR2 constitutes a reductively displaceable moiety, and R and R1 have the same meanings as defined in Formulae I and II, reductive displacement being accomplished by catalytic hydrogenation or chemical reduction. The 3-methylene cepham compounds are isomerized in dimethylacetamide in the presence of a tertiary alkyl amine to provide 3-methyl-7-acylamido- DELTA 3-cephem-4-carboxylic acids and esters.</p> |
