7 BETA-{D-2-(3,4-DIHYDROXYPHENYL)-2-{(4-ETHYL-2,3- DIOXOPIPERAZIN-1-YL)CARBONYLAMINO{ACETAMIDO)-7 ALPHA- FORMAMIDO-3-(PYRIDINIUM)METHYL-CEPH-3-EM-4-CARBOXYLIC ESTERS OR CARBOXYLATES

摘要

beta -Lactam antibiotics have the formula (Ia) or are pharmaceutically acceptable salts or pharmaceutically acceptable in vivo hydrolysable esters thereof: CHEM in which the group CO2R1 is carboxy or a carboxylate anion. The use of the compounds and processes for their preparation are disclosed.