3-Hydroxy-cephem cpds. prepn. - via new alpha-substd. 3-amino-4-mercapto-2-azetidinone-1-acetic acid derivs

摘要

7-Amino-3-hydroxy-3-cephem-4-carboxylic acid derivs of formula (I) are prepd. by (a) halogenating a 1-(2-Y-1-COX-1-propenyl)-3-amino-4-(protected mercapto)-2-azetidinone of formula (II), (b) deprotecting the resulting 1-(3-halo-2-Y-1-COX-1-propenyl) cpd. of formula (III), and (c) cyclising the product, (where Q is opt. substd. amino, pref. acylamino, and R is a protecting gp., or Q and SR together can form a -N=CR1-S- gp., whwe where R1 is a substituent capable of forming a COR1 acyl radical; X is OH or a carboxy-protecting gp.; Y is OH (opt. in ketonic form) or a disubstd. amino gp.).