Asymmetric Epoxidation Of Electron-Deficient Alkenes

Porter, Michael J.; Skidmore, John


Asymmetric epoxidation reactions have the distinction of being among the first enantioselective transformations to be widely sued in organic synthesis. The Sharpless asymmetric epoxidation is arguably one of the most important methods for the synthesis of enantiomerically enriched intermediates uses en route to a wide range of synthetic targets. To date most examples have employed electrophilic oxidizing agents and are thus applicable to electron-neutral or electron-rich double bonds. On the other hand alkenes substituted with electron-withdrawing groups often react inefficiently with electrophilic oxidizing agents; such alkanes are more readily epoxidized using nucleophilic oxidants. The Weitz-Scheffer epoxidation of alpha,beta-unsaturated ketones to the corresponding epoxy ketones using basic hydrogen peroxide is the classical nucleophilic epoxidation reaction.

This chapter considers the more general case of the conversion of an electron deficient alkene into the corresponding epoxide in an enantioselective fashion. Only methods based on chiral reagents or catalysts are covered. This review covers the literature to the end of 2005.