László Tamás, Tamás E. Gunda and Ferenc Sztaricskai:
On the Preparation of 2-Substituted Cephalosporin Sulfoxides via Anionic Intermediates.
J. Chem. Soc. Perkin I, 721-725 (1999)

Abstract: The LDA-generated anions of cephalosporin sulfoxides may give rise to a mixture of C-2 and/or C-4 substituted products owing to the delocalised nature of the negative charge. Under optimized conditions -crotonyl- and 2α-cinnamoylcephalosporin sulfoxides can be obtained in satisfactory yields, which are useful starting materials for cycloaddition reactions leading to novel analogues with β-lactamase or HLE enzyme inhibiting properties.