Epoxidation of Alkenes

In the laboratory, alkenes can be oxidized to form epoxides using a peroxyacid, RCO₃H, such as meta-chloroperoxybenzoic acid. Epoxides, also known as oxiranes, are cyclic ethers characterized by a three-membered ring containing an oxygen atom. For instance:

The addition occurs with syn stereochemistry (i.e both C-O bonds on the same face).  The peroxy acid transfers the oxygen via  a one step mechanism as follows:

On an industrial scale (or lab), epoxides can be synthesized from halohydrins.

Application to Crixivan

This halohydrin route has been successfully used in the synthesis of the epoxide fragment of Crixivan as shown below.  The allyl acetonide is first converted to the iodohydrin using NIS (N-iodosuccinimide) follows by treatment with NaOCH3 (sodium methoxide) to form the epoxide fragment.