.alpha.-(Etherified oximino)carboxylic acids, represented by the formula:- ##STR1## where R is hydrogen or an organic group having 1-20 carbon atoms and R.sup.a is an etherifying monovalent organic group having 1-16 carbon atoms linked to the oxygen atom through a carbon atom, and the corresponding acid chlorides, are useful intermediates in the preparation of highly active, highly .beta.-lactamase-stable 7.beta.-[.alpha.-(etherified oximino)acylamido]-ceph-3-em-4-carboxylic acid antibiotics. The compounds are syn isomers or exist as mixtures of syn and anti isomers containing at least 75% of the syn isomer.
.alpha.-(醚化氧
肟基)
羧酸,
化学式表示为:##STR1## 其中R表示氢或具有1-20个碳原子的有机基团,R.sup.a是具有1-16个碳原子的醚化一价有机基团,通过碳原子连接到氧原子,相应的酸
氯化物是制备高活性、高β-内酰胺酶稳定性7.β-[.alpha.-(醚化氧
肟基)酰胺基]-头孢-3-酰基-4-
羧酸类抗生素的有用中间体。这些化合物是syn异构体或存在至少75%syn异构体的syn和anti异构体混合物。