PROCESS FOR PREPARING CEPHALOSPORIN INTERMEDIATES

摘要

7-Substd. -3-cephem intermediate N,N-dimethyl acetamide solvates of formula (I)[DMAC=N,N-dimethylacetamide are prepd. by condensating [(Z)-2-(2-tert-butoxycarbonyl prop-2-oxyimino)-2(2- triphenylmethylaminothiazol-4-yl acetyl halide with (6R, 7R)-7amino- 3-(1-pyridiium-methyl)ceph-3-em-4-carboxylate in the presence of N,N- dimethylacetamide. Thus, (I) is obtained in 65.2% yield by acylating the aminocephem in DMAC. Deblocking of (I) with HCO2H-HCl give 62% ceftazidime.2HCl. (I) crystallises directly from a soln. of the cephem in DMAC, so that other purification steps are avoided.