Abstract: Cefazolin, cefazedone, cefoperazone, cefamandole, cefatrizine or ceftriaxone is prepared by reacting glutaryl 7-ACA of the formula: ##STR1## with a compound of formula (II):R--SH (II)wherein R is 5-methyl-1,3,4-thiadiazol-2-yl, 1H-1,2,3-triazol-4-yl, 1-methyl-tetrazol-5-yl or1,2,5,6-tetrahydro-2-methyl-5,6-dioxo-1,2,4-triazin-3-yl group, and R.sup.1 and R.sup.2 are both hydrogen and the other is an acyl group, in an aqueous solution in an amount of 3-5 mols per mol of glutaryl 7-ACA to about 90.degree. C. and for a time from about 2 to about 10 hours;optionally recovering the excess of the compound of formula (II), thereby preparing a compound of formula (III) in an aqueous solution: ##STR2## wherein R is as above defined and optionally deacylating said compound of formula (III); andconverting the resulting compound of formula (I) ##STR3## wherein R, R.sup.1 and R.sup.2 are as defined above in the presence of a non-chlorinated solvent into one of said cephalosporins.

Abstract: The present invention relates to a process for preparing a compound of formula (I) ##STR1## wherein R is an heterocyclic group which contains at least one nitrogen atom with or without oxygen or sulphur and R.sup.1 and R.sup.2 are both hydrogen atoms or one of them is an hydrogen atom and the other is an acyl group; the process comprising reacting a compound of formula (II) ##STR2## wherein R.sup.1 and R.sup.2 are each as defined above, and wherein, if necessary, any reactive group is protected by a suitable protective group, or a salt thereof, with a compound of formula (III)R--SH (III)wherein R is as defined above, or a salt thereof, in the presence of an acid and of a compound of formula (IV) ##STR3## wherein each of R.sup.3 and R.sup.4 is a C.sub.1 -C.sub.4 alkyl group or R.sup.3 and R.sup.4 taken together are a C.sub.2 or C.sub.3 alkylene chain and, if necessary, removing the protective groups possibly present.