Imperial Chemical Industries Limited

Evan W Snape

Stephen J Pegg

Frank Lotus

A process for preparing compounds of the formula I: ##STR1## wherein X is sulphur, oxygen, methylene or sulphinyl (R or S configuration), R.sup.3 is hydrogen or methoxy, R.sup.4 is an optionally substituted (1-4C)alky group, Y is hydrogen or a carboxyl protecting group and Q is an optionally protected amino group or an acylamino group, which comprises reacting a compound of formula (II) ##STR2## with a compound of formula (III) ##STR3## wherein R.sup.4 is as defined above and W and Z represent hydrogen atoms or a group or groups removable to yield the compound of formula (I). The compounds of the formula I are useful intermediates in the preparation of cephalosporin antibiotics.

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Congleton, United Kingdom

Evan W Snape