| 摘要 |
A process to prepare the E isomer of a 3-substituted (6R,7R)-7-phenyl-acetamido-ceph-3-em-4-carboxylic acid from a mixture of the E and Z-isomer of either the corresponding tert-butyl or the corresponding 4-methoxybenzyl ester of a 3-substituted (6R,7R)-7-phenylacetamido-ceph-3-em-4-carboxylate, characterized by the application of a compound selected from the group titanium tetrachloride, tin tetrachloride and tellurium tetrachloride. |
