Corey-Winter Olefin Synthesis

Conversion of 1,2-diols to alkenes. The cyclic thiocarbonate is available from reaction of the diol with thiophosgene or thiocarbonyldiimidazole, and reacts with added trimethylphosphite via a syn-elimination to the alkene.

---

Mechanism of the Corey-Winter Olefin Synthesis

It is assumed that the reaction proceeds with attack of phosphite on sulphur leading to a carbene, which may react with a second equivalent of phosphite during the cycloreversion that splits out carbon dioxide and yields the product alkene.