3-Methylenecepham-4-carboxylic acids and esters of the Formula I and 3-methyl-.DELTA..sup.3 -cephem-4-carboxylic acids and esters of the Formula II ##SPC1## where R is hydrogen or an organic acyl group and R.sub.1 is hydrogen, C.sub.1 -C.sub.4 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 ##SPC2## where R.sub.2 is an organic residue such that --SR.sub.2 constitutes a reductively displaceable moiety, and R and R.sub.1 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..sup.3 -cephem-4-carboxylic acids and esters.
通过催化氢化或
化学还原,通过Formula III中3-取代甲基
头孢菌素的还原位置置换,制备Formula I中3-亚甲基头孢烯-4-
羧酸和酯以及Formula II中3-甲基-Δ3-头孢烯-4-
羧酸和酯,其中R为氢或有机酰基,R1为氢,C1-C4烷基,
羧酸保护基或药用可接受阳离子。在三级烷基胺存在下,3-亚甲基头孢烯化合物在二甲基乙酰胺中异构化,以提供3-甲基-7-酰胺基-Δ3-头孢烯-4-
羧酸和酯。