Abstract: Allylic unsaturated lactones 5E and 5Z can be epoxidized and osmylated with useful stereocontrol. The epoxidations follow the pattern predicted from evaluation of local conformer effects, and epoxides 8 and 14 are favored. These products correspond to peripheral attack on the exposed olefin face of conformers similar to 1 (Z-alkene) or 2 (E- alkene). As in the case of simple carbocyclic alkenes, osmylation of the Z-isomer (5Z) ...
