ANALOGIFREMGANGSMAADE TIL FREMSTILLING AF CEPHALOSPORINFORBINDELSER I DEN SYN-ISOMERE FORM ELLER UGIFTIGE SALTE DERAF

1399086 Cephalosporin compounds GLAXO LABORATORIES Ltd 12 May 1972 [14 May 1971 1 Oct 1971] 15082/71 and 45884/71 Heading C2C Novel 7 - acylamidoceph - 3 - em carboxylic acids and their salts, esters and 1-sulphoxides, wherein the acylamido group has the structure in which R is hydrogen or an organic group and Ra is an etherifying monovalent organic group linked to the oxygen atom through a carbon atom, the said compounds having the syn isomeric form as regards the configuration of the group ORa with respect to the carboxamido group, or being a mixture of the syn and anti isomers containing at least 75% of the syn isomer, are prepared by acylating a 7-amino or 7-isocyanato-cephem carboxylic acid or its salt, ester or 1-oxide, with an acylating agent corresponding to the acid of formula and then recovering the desired acylamidocephem compound, if necessary after separation of the syn and anti isomers.