Abstract: There is described a process for preparing a sulphoxide of the formula ##STR1## in which R.sup.1, R.sup.2, R.sup.3 and R.sup.4, taken individually, are alkyl, alkoxy or aryl groups, X is an alkylene group, R.sup.5 is a carboxylic acid protecting group and Y is a linking group through one or two carbon atoms forming a penam or cephem nucleus, which comprises reacting a compound of formula ##STR2## with an oxidizing agent. .alpha.-Sulphoxide compounds of formula (I) are also provided as novel intermediates.

Abstract: There is described a process for preparing a sulphoxide of the formula ##STR1## in which R.sup.1, R.sup.2, R.sup.3 and R.sup.4, taken individually, are alkyl, alkoxy or aryl groups, X is an alkylene group, R.sup.5 is a carboxylic acid protecting group and Y is a linking group through one or two carbon atoms forming a penam or cephem nucleus, which comprises reacting a compound of formula ##STR2## with an oxidizing agent. .alpha.-Sulphoxide compounds of formula (I) are also provided as novel intermediates.

Abstract: There is described a process for preparing an enamine of formula (IX): ##STR1## where R.sup.2 is a carboxylic acid protecting group and R.sup.3 is the residue of a carboxylic acid derived acyl group and where R.sup.5 and R.sup.6 are the same or different C.sub.1-4 alkyl or C.sub.7-10 aralkyl groups; or taken together with the adjacent nitrogen atom form a heterocyclic ring containing from 4 to 8 carbon atoms and optionally a further heteroatom selected from oxygen and nitrogen; by reacting a compound of formula (XII): ##STR2## with an amine of formula HNR.sup.5 R.sup.6, the reactant of formula (XII) being prepared by reaction of an appropriate enol derivative with a phosphorus reagent. The enamines of formula (IX) are useful in the preparation of 3-hydroxycephalosporins.

Abstract: 3-Exomethylenecepham sulfoxides are prepared by the reaction of 3-methyl-3-halocepham sulfoxides with mercuric or mercurous perchlorate.