、 Methyl 7beta-benzoylamino-3chloromethyl-3-cephem-4-carboxylate 、 水 以
四氢呋喃 为溶剂,
反应 0.7h,
以After the usual work-up and column chromatography, the title product was isolated in 96% yield的产率得到Methyl 7beta-benzoylamino-3-methylenecepham-4carboxylate
The present invention relates to a process for the preparation of exomethylene cephams, which are useful intermediates in the production of many useful .beta.-lactam antibiotics. More particularly there is provided a process for preparing a compound of formula I ##STR1## wherein n is O or 1, R.sub.1 is hydrogen atom or an organic residue and R.sub.2 is a carboxy protecting group, which process comprises reacting a compound of the formula II ##STR2## wherein X is halogen atom or acetoxy group and R.sub.1 n and R.sub.2 are as defined above with a lanthanide complex.