| 摘要 |
7-Amino-3-hydroxy-3-cephem esters react with a chlorinating agent, e.g. phosgene, thionyl chloride and preferably PCl3-DMF to provide 7 beta -[(dimethylaminomethylene)amino]-3-chloro-3-cephem esters which on reaction with a carboxylic acid, a percarboxylic acid, or a phenol, having a pH in water of about 2-5, afford 7 beta -formamido-3-chloro-3-cephem esters, and corresponding 2-cephem esters. Percarboxylic acids provide 7 beta -formamido-3-chloro-3-cephem ester 1-oxides. The 7-formamido derivatives provide the 7-amino-3-chloro-3-cephem ester on acid hydrolysis. The 7-amino-3-chloro esters are useful for preparing antibiotics.
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