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DOI: 10.1055/s-0030-1261135
Purification of Alkene Stereoisomers through Z-Selective Ethenolysis
Contributor(s):Mark Lautens, Stephen G. NewmanMassachusetts Institute of Technology, Cambridge and Boston College, Chestnut Hill, USA
Isolation of Pure Disubstituted E Olefins through Mo-Catalyzed Z-Selective Ethenolysis of Stereoisomeric Mixtures
J. Am. Chem. Soc. 2011, 133: 11512-11514
Publication History
Publication Date:
20 September 2011 (online)
Key words
molybdenum - Z-alkenes - stereoisomer purification
Significance
Many methods exist for preparing disubstituted E-olefins, such as the Horner-Wadsworth-Emmons reaction and olefin cross-metathesis. While these reactions have proven to be highly reliable and practical, the undesired Z-isomer is often difficult to separate by chromatography or distillation. In the present communication, the authors disclose how pure E-olefins can be obtained from an E/Z mixture through the selective ethenolysis of the Z-isomer.
Comment
The by-products of the reaction are of much lower molecular weight than the starting materials, so the pure E-isomer can often be obtained through distillation. The rate of ethenolysis is found to be up to 30 times faster for the Z-isomer, explaining why such a highly pure E-olefin can be obtained. The scale of the reactions was not mentioned.