Question

Treatment of an alpha,beta-unsaturated ketone with basic aqueous hydrogen peroxide yields an epoxy ketone. the reaction is specific to unsaturated ketones; isolated alkene double bonds do not react. on a sheet of paper, write a mechanism for the alkene to epoxide reaction. then, in the window below, draw the first intermediate in your mechanism.

Answer 1

The reaction mechanism for an alpha,beta-unsaturated ketone to react with basic peroxide to form an epoxide is shown below with a general ketone. The basic hydroxide is used to deprotonate the peroxide molecule to create a strong HOO- nucleophile. The peroxide then attacks the beta-carbon of the alkene and this pushes the electrons up to the oxygen of the carbonyl. This is the first intermediate that is formed during this reaction.

After the intermediate is formed, the lone pair from the oxygen pushes back down to form the carbonyl once more and this breaks a carbon-carbon bond which attacks the oxygen of the peroxy group, ultimately substituting an -OH group and forming the final epoxide ketone product.