| 摘要 |
The invention relates to a process for the preparation of 7 beta -acylamido-3-methylceph-3-em-4-carboxylic acid esters from compounds of the penicillin type, in particular, 6 beta -acylamido penicillanic acid 1-oxide esters, in the presence of a catalyst selected from a mono-O-substituted orthophosphoric acid, an 0,0-di(aryl substituted) orthophosphoric acid, a salt or complex formed from a nitrogen base having a pKb of not less than 4 and a mono-0-substituted orthophosphoric acid or an 0,0-di(aryl substituted) orthophosphoric acid. The salt or complex may be formed in situ in the reaction mixture. |
