The Corey–Winter olefin synthesis (also known as Corey–Winter–Eastwood olefination) is a series of chemical reactions for converting 1,2-diols into olefins.[1][2][3][4] It is named for the American chemist and Nobelist Elias James Corey and the American-Estonian chemist Roland Arthur Edwin Winter.[5]
Corey-Winter Olefination
Often, thiocarbonyldiimidazole is used instead of thiophosgene as shown above, since thiophosgene has a similar toxicity profile as phosgene, whereas thiocarbonyldiimidazole is a much safer alternative.
Mechanismedit
The reaction mechanism involves the formation of a cyclic thiocarbonate from the diol and thiophosgene. The second step involves treatment with trimethyl phosphite, which attacks the sulfur atom, producing S=P(OMe)3 (driven by the formation of a strong P=S double bond) and leaving a carbene.[6] This carbene collapses with loss of carbon dioxide to give the olefin.
Proposed Mechanism of the Corey-Winter Olefination
An alternative mechanism does not involve a free carbene intermediate, but rather involves attack of the carbanion by a second molecule of trimethylphosphite with concomitant cleavage of the sulfur-carbon bond. The phosphorus stabilized carbanion then undergoes an elimination to give the alkene, along with an acyl phosphite, which then decarboxylates.
Alternative Mechanism
The Corey-Winter olefination is a stereospecific reaction:[1] a trans-diol gives a trans-alkene, while a cis-diol gives a cis-alkene as the product. For instance, cis- and trans-1,2-cyclodecanediol gives the respective cis- and trans-cyclodecene.
Referencesedit
^ abCorey, E. J.; Winter, R. A. E. (1963). "A New, Stereospecific Olefin Synthesis from 1,2-Diols". J. Am. Chem. Soc.85 (17): 2677–2678. doi:10.1021/ja00900a043.
^Corey, E. J.; Carey, F. A.; Winter, R. A. E. (1965). "Stereospecific Syntheses of Olefins from 1,2-Thionocarbonates and 1,2-Trithiocarbonates. trans-Cycloheptene". J. Am. Chem. Soc. 87 (4): 934–935. doi:10.1021/ja01082a057.
^Corey, E. J.; Hopkins, J. (1982). "A mild procedure for the conversion of 1,2-diols to olefins". Tetrahedron Lett.23 (19): 1979–1982. doi:10.1016/S0040-4039(00)87238-X.
^Crank, G.; Eastwood, F. W. (1964). "Derivatives of orthoacids. II. The preparation of olefins from 1,2-diols". Australian Journal of Chemistry. 17 (12): 1392–1398. doi:10.1071/CH9641392.
^Block, E. Org. React.1984, 30, 457. doi:10.1002/0471264180.or030.02
^Horton, D.; Tindall, Jr., C. G. J. Org. Chem.1970, 35(10), 3558-3559. (doi:10.1021/jo00835a082)
April 18, 2024
corey, winter, olefin, synthesis, also, known, corey, winter, eastwood, olefination, series, chemical, reactions, converting, diols, into, olefins, named, american, chemist, nobelist, elias, james, corey, american, estonian, chemist, roland, arthur, edwin, win. The Corey Winter olefin synthesis also known as Corey Winter Eastwood olefination is a series of chemical reactions for converting 1 2 diols into olefins 1 2 3 4 It is named for the American chemist and Nobelist Elias James Corey and the American Estonian chemist Roland Arthur Edwin Winter 5 Corey Winter OlefinationOften thiocarbonyldiimidazole is used instead of thiophosgene as shown above since thiophosgene has a similar toxicity profile as phosgene whereas thiocarbonyldiimidazole is a much safer alternative Mechanism editThe reaction mechanism involves the formation of a cyclic thiocarbonate from the diol and thiophosgene The second step involves treatment with trimethyl phosphite which attacks the sulfur atom producing S P OMe 3 driven by the formation of a strong P S double bond and leaving a carbene 6 This carbene collapses with loss of carbon dioxide to give the olefin nbsp Proposed Mechanism of the Corey Winter OlefinationAn alternative mechanism does not involve a free carbene intermediate but rather involves attack of the carbanion by a second molecule of trimethylphosphite with concomitant cleavage of the sulfur carbon bond The phosphorus stabilized carbanion then undergoes an elimination to give the alkene along with an acyl phosphite which then decarboxylates nbsp Alternative MechanismThe Corey Winter olefination is a stereospecific reaction 1 a trans diol gives a trans alkene while a cis diol gives a cis alkene as the product For instance cis and trans 1 2 cyclodecanediol gives the respective cis and trans cyclodecene References edit a b Corey E J Winter R A E 1963 A New Stereospecific Olefin Synthesis from 1 2 Diols J Am Chem Soc 85 17 2677 2678 doi 10 1021 ja00900a043 Corey E J Carey F A Winter R A E 1965 Stereospecific Syntheses of Olefins from 1 2 Thionocarbonates and 1 2 Trithiocarbonates trans Cycloheptene J Am Chem Soc 87 4 934 935 doi 10 1021 ja01082a057 Corey E J Hopkins J 1982 A mild procedure for the conversion of 1 2 diols to olefins Tetrahedron Lett 23 19 1979 1982 doi 10 1016 S0040 4039 00 87238 X Crank G Eastwood F W 1964 Derivatives of orthoacids II The preparation of olefins from 1 2 diols Australian Journal of Chemistry 17 12 1392 1398 doi 10 1071 CH9641392 Block E Org React 1984 30 457 doi 10 1002 0471264180 or030 02 Horton D Tindall Jr C G J Org Chem 1970 35 10 3558 3559 doi 10 1021 jo00835a082 Retrieved from https en wikipedia org w index php title Corey Winter olefin synthesis amp oldid 1171191533, wikipedia, wiki, book, books, library,
