Other Epoxidation Methods
Other Epoxidation Methods: Halcon Reaction
Because of the activating and directive influence of OH groups, allylic alcohols are important starting materials for the Halcon reaction. Good yields are obtained by using catalytic amounts of VO(acac)2 and tert-butyl hydroperoxide as epoxidation agent.
In the first step, the allylic alcohol forms a isomer preferentially adds to the oxygen atom in anti position to the OH group while the (E) isomer forms the syn derivative.with the metal compound in which the allylic alcohol is coordinated to the metal atom through the hydroxy group. In case of cyclic alcohols, epoxidation with tert-butyl hydroperoxide takes place cis to the hydroxy group. Acyclic alcohols form two different epoxides. The (Z)