Categories: C=C Bond Formation >
Synthesis of (E)-alkenes
Aryl tosylhydrazones react with t-BuOK, ClFeTPP, (MeO)3P, and aldehydes to furnish olefins with high E selectivity through a Wittig-type pathway via the corresponding diazo compounds, metal carbenes and phosphorous ylides. A Horner-Wadsworth-Emmons-type reaction of ethyl diazoacetate with aldehydes occurs with high E selectivity in the presence of LiBr via the phosphonate anion, formed through an Arbuzov reaction under completely base-free conditions.
V. K. Aggarwal, J. R. Fulton, C. G. Sheldon, J. de Vicente, J. Am. Chem. Soc., 2003, 125, 6034-6035.
An efficient and facile copper(II) acetylacetonate catalyzed synthesis of functionalized bis(arylmethyl)zinc reagents from arylmethyl halides followed by olefination with aromatic aldehydes gives (E)-stilbenes in good yields. Aluminum trichloride was found to be the key ingredient in these reactions.
Y. Fu, X. Hu, Y. Chen, Y. Yang, H. Hou, Y. Hu, Synthesis, 2012, 44, 1030-1036.
N-sulfonyl imines undergo olefination reactions with various benzylidenetriphenylphosphoranes or allylidenetriphenylphosphoranes under mild reaction conditions to afford an array of both Z- and E-isomers of conjugated alkenes in good to excellent yields and with greater than 99:1 stereoselectivity depending on the N-sulfonyl group.
D.-J. Dong, H.-H. Li, S.-K. Tian, J. Am. Chem. Soc., 2010, 132, 5018-5020.
A modification of the classical Julia-Lythgoe olefination using sulfoxides instead of sulfones affords 1,2-di-, tri-, and tetrasubstituted olefins in moderate to excellent yields and E/Z selectivity. The mild conditions involve in situ benzoylation and SmI2/HMPA-mediated reductive elimination as key steps.
J. Pospisil, T. Pospisil, I. E. Marko, Org. Lett., 2005, 7, 2373-2376.
A stereoselective synthesis of tetrasubstituted alkenylboronates, which are useful synthetic intermediates for further functionalizations, was established via the lithiation/nucleophilic addition reaction of 1,1-organodiboronates to carbonyl compounds.
K. Endo, M. Hirokami, T. Shibata, J. Org. Chem., 2010, 75, 3469-3472.
A versatile and operationally simple base-catalyzed multi-component domino reaction between α,β-unsaturated carbonyl compounds, aldehydes, and alcohols is described, providing a new efficient, and stereoselective one-pot preparation of trisubstituted alkenes and 1,3-dienes.
H. Habib-Zahmani, S. Hacini, C. Bories, J. Rodriguez, Synthesis, 2005, 2151-2156.
Fe(0) is cost-effective, environmentally friendly alternative to Cr(II) for the olefination of carbonyls by activated polyhalides. Fe(0) proved compatible with a wide range of functionality, such as unprotected phenol, aryl nitro, carboxylic acid, and alkyl nitrile.
J. R. Falck, R. Bejot, D. K. Barma, A. Bandyopadhyay, S. Joseph, C. Mioskowski, J. Org. Chem., 2006, 71, 8178-8182.
A series of vinyl sulfonamides was synthesized using the Horner reaction of aldehydes and diphenylphosphorylmethanesulfonamide. The sulfonamide reagent was easily prepared and can be stored indefinitely.
D. C. Reuter, J. E. McIntosh, A. C. Guinn, A. M. Madera, Synthesis, 2003, 2321-2324.