Process for the preparation of cephalosporin compounds

In a process for the preparation of a compound of formula ##STR14## wherein R.sup.1 represents a C.sub.1 -C.sub.40 protected amino group, R.sup.2 represents a group selected from the group consisting of hydrogen atoms and carboxyl blocking groups, R.sup.3 represents a group selected from the group consisting of hydrogen atoms and C.sub.1 -C.sub.8 alkyl, C.sub.1 -C.sub.8 alkylthio and C.sub.1 -C.sub.8 alkoxy groups;

• Z is >S or >S.fwdarw.O (.alpha.- or .beta.-);
• and the dotted line bridging the 2-, 3- and 4-positions of the molecule indicates that the compounds may be ceph-2-em or ceph-3-em compounds, and salts thereof, the steps which consist of reacting a compound of formula ##STR15## wherein R.sup.1, R.sup.2, R.sup.3, Z and the dotted line are as herein defined, and R.sup.4 and R.sup.5, which may be the same or different, each represents a group selected from the group consisting of alkyl, aralkyl, alicyclic or aryl groups, or R.sup.4 and R.sup.5 together form a divalent group with at least 3 carbon atoms bridging the oxygen atoms, with a compound of formula ##STR16## wherein R.sup.6, R.sup.7 and R.sup.8, which may be the same or different, each represents a group selected from the group consisting of alkyl, aralkyl, alicyclic or aryl groups, or any two of R.sup.6, R.sup.7 and R.sup.8 together form a divalent group containing at least 3 carbon atoms;
• and X represents an atom selected from the group consisting of chlorine, bromine or iodine atoms, followed by hydrolysis.