Process for the preparation of a novel cystalline, stable form of the syn isomer of (6R,7R)-7-2-(2-amino-4- thiazolyl)-(Z)-2(1-tert-butoxycarbonyl-1- methylethoxy)iminoacetamido-3-(1-pyridiniummethyl)-3- cephem-4-carboxylate

摘要

The invention relates to a process for the preparation of a novel crystalline, stable form of the syn isomer of (6R,7R)-7-[[2-(2-amino-4-thiazolyl)-(Z)-2(1-tert- butoxycarbonyl-1-methylethoxy)imino]acetamido]-3-(1- pyridiniummethyl)-3-cephem-4-carboxylate (beta form) of the formula I and is characterized in that the syn isomer of the compound of the formula I is crystallized from an aqueous solution, preferably having a pH of 3, by increasing the pH to 3.5 to 7.5. IMAGE