Enantioselective synthesis of alkyl-substituted eight-membered lactones byClaisen rearrangement

The Claisen rearrangement of alkenyl-substituted ketene acetals (produced i n situ by selenoxide elimination from the corresponding phenylselenoacetald ehyde-derived acetals of enantiomerically pure 1,3-diol derivatives) afford ed unsaturated eight-membered lactones with control of stereochemistry of m ethyl substituents at C-4, C-5 and C-7, as well as a fused system.