Question

What is sharpless epoxidation?

Answer 1

Sharpless epoxidation is the enantioselective epoxidation of prochiral allylic alcohols.

The oxidizing agent is t-butyl hydroperoxide. The catalyst is a complex formed from titanium(IV) isopropoxide and diethyl tartrate (DET). The reaction uses 5–10 mol % of the catalyst in the presence of 3Å molecular sieves.

The enantiomer of the diethyl tartrate determines the stereochemistry of the epoxide.

If you draw the alkene in a plane with the OH in the top right corner, the (+)-DET attacks from the top. The (-)-DET attacks from the bottom.