Photochemical transformations of cephalosporins
Abstract
Two new photochemical reactions of the ceph-3-em 4 have been discovered. In methanol, rearrangement to the 2-isopropenyl-6-methoxy-4-oxotetrahydro-1,3-thiazine 14 occurs, whilst in tetrahydrofuran–acetone, regio- and stereo-specific addition leads to the tricyclic lactone 25.