| 摘要 |
There are presented compounds of the formula <IMAGE> I wherein R1 is one of the 3-substituents usable in cephalosporin chemistry, R2 is hydrogen, lower alkyl or COOR3-lower alkyl, wherein R3 is hydrogen, a cation of a base or a readily hydrolyzable ester group, and X is sulphur, oxygen or one of the groups -SO- and -SO2-, and the readily hydrolyzable esters, readily hydrolyzable ethers and salts of these compounds and hydrates of the compounds of formula I or of their esters, ethers and salts, also presented are methods for the manufacture of these compounds as well as compounds used in their manufacture.
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