Corey-Winter olefin synthesis

The Corey-Winter olefin synthesis is a series of chemical reactions for converting 1,2-diols into olefins.^[1][2] It is named for the American chemist and Nobelist Elias James Corey and the American-Estonian chemist Roland Arthur Edwin Winter.

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Often, thiocarbonyldiimidazole is used instead of thiophosgene as shown above.

Mechanism

The reaction mechanism involves the formation of a cyclic thio-carbonate from the diol and thiophosgene. The second step involves treatment with trimethyl phosphite, which attacks the sulphur atom, producing S=P(OMe)₃ (driven by the formation of a strong P=S double bond) and leaving a carbene.^[3] This carbene collapses with loss of carbon dioxide to give the olefin.

References

1. ^  Corey, E. J.; Winter, R. A. E. J. Am. Chem. Soc. 1963, 85, 2677. (doi:10.1021/ja00900a043)
2. ^  Corey, E. J.; Hopkiss, P. B. Tetrahedron Lett. 1982, 23, 1797.
3. ^  Horton, D.; Tindall, Jr., C. G. J. Org. Chem. 1970, 35(10), 3558-3559. (doi:10.1021/jo00835a082)