Weitz‐Scheffer Epoxidation

The epoxidation of electron‐deficient olefins using hydrogen peroxide in a strong alkaline solution and is generally known as the Weitz–Scheffer epoxidation. Occasionally, it is also referred to as the Weitz–Scheffer reaction. The asymmetric Weitz–Scheffer epoxidation has been widely used in organic synthesis, using different oxygen sources in the presence of methylpseudoephedrine or polybinaphthol and diethylzinc. The asymmetric induction from cinchona alkaloids in Wynberg's protocol can be attributed to the phase transfer catalyst as indicated by the increased % e.e. for the epoxidation and higher cyclodextrin/quinone ratios. However, the most important modification of the asymmetricWeitz–Scheffer epoxidation has been developed using optically active secondary hydroperoxide as the oxidation reagent, in the presence of either KOH or an organic base. Furthermore, potassium cation has a profound effect on the enantioselectivity due to the formation of coordination complex. This reaction has important applications for the epoxidation of electron‐poor olefins.