The 3-bromomethyl derivative 2c, obtained by photoinitiated bromination of the corresponding 3-Me compound 1c, has been converted into the antibiotics cephalothin 18 and cephaloridine 20. Reaction of 2c with lithium dimethyl-and diphenyl-cuprate led to the intermediates 22 and 24 respectively. Further transformation of 24 provided the 3-benzyl derivative 27, an isostere of cephaloridine.
![2,2,2-trichloroethyl (1S,6R,7R)-N-[7-(thien-2-ylacetamido)ceph-3-em-3-ylmethyl]pyridinium chloride 4-carboxylate 1-oxide结构式](https://image.chemsrc.com/caspic/205/33492-94-3.png)
