| 摘要 |
<p>B-Lactam antibiotics particularly cephamycin and cephalosporin derivatives, having the formula (I): < IMG > (I) (wherein R1 represents an acyl group, R2 represents a hydrogen atom or a methoxy group, R3 represents an amidinothio group or a heterocyclkylthio group and X represents a sulphur atom, an oxygen atom or a methylene group) may be prepared in high yields, with a minimum of side reactions by reacting a compound of formula (II): < IMG > (II) (wherein R4 represents a hydrogen or halogen atom and R5 represents an amino group protected by an electronattractive group) with an acyl halide of Formula R1-Y (wherein Y represents d halogen atom), in the presence of a halogenated aliphatic hydrocarbon solvent, to give a compound of formula (IV): < IMG > (IV) and then removing the phenacyl or halophenacyl protecting group by reaction with zinc and in acid selected from inorganic acids, monoesters of dibasic inorganic acids and sulphonic acids. The resulting compound of formula (I) may then be salified in the usual way to give a pharmaceutically acceptable salt thereof.</p> |
