Preparation of .DELTA.3-7.ALPHA.-phenylacetamidodesacetoxycephalosporanic acid.
作者:P. G. CLAES、G. DECOSTER、L. A. KERREMANS、H. VANDERHAEGHE
DOI:10.7164/antibiotics.32.820
日期:——
Δ3-7α-Phenylacetamidodesacetoxycephalosporanic acid was prepared by ring expansion of 6-epi-benzylpenicillin-S-sulfoxide, using N, O-bis(trimethylsilyl)acetamide( BSA) as silylating and dehydrating agent and α-picoline/α-picoline hydrobromide as catalyst. In some experiments 7α-phenylacetamido-3β-bromo-3α-methylcepham-4α-carboxylic acid was obtained as a side product. 7-Epimers in the desacetoxycephalosporanic series were also prepared by base-catalyzed epimerization of the benzyl 7 β-(p -nitrobenzylideneimino)desacetoxycephalosporanate and of the S-sulfoxide of natural methyl 6-phenylacetamidodesacetoxycephalosporanate. In both reactions 1, 5-diazabicyclo(4.3.0)non-5-ene( DBN) was used as epimerization catalyst.
以N,O-双(三甲基硅基)乙酰胺(BSA)为硅烷化剂和脱水剂,α-甲基吡啶/α-甲基吡啶氢溴酸盐为反应剂,通过6-表苄青霉素-S-亚砜扩环制备Δ3-7α-苯基乙酰胺去乙酰氧基头孢烷酸。催化剂。在一些实验中,获得了副产物7α-苯基乙酰胺-3β-溴-3α-甲基头孢姆-4α-羧酸。去乙酰氧基头孢菌素系列中的 7-差向异构体也通过 7 β-(对硝基亚氨基)去乙酰氧基头孢菌酸苄酯和天然 6-苯基乙酰胺去乙酰氧基头孢菌酸甲酯的 S-亚砜的碱催化差向异构化来制备。在两个反应1中,5-二氮杂双环(4.3.0)壬-5-烯(DBN)均用作差向异构催化剂。