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The mechanism of the Horner-Wadsworth-Emmons reaction. The ratio of alkene isomers 5 and 6 is not dependent upon the stereochemical outcome of the initial carbanion addition and upon the ability of the intermediates to equilibrate. The electron-withdrawing group (EWG) alpha to the phosphonate is necessary for the final elimination to occur.
William D. Emmons (November 18, 1924 – December 8, 2001) was an American chemist and published with William S. Wadsworth a modification to the Wittig-Horner reaction using phosphonate-stabilized carbanions, now called the Horner-Wadsworth-Emmons reaction in his honor.
Triethyl phosphonoacetate is a reagent for organic synthesis used in the Horner-Wadsworth-Emmons reaction (HWE) or the Horner-Emmons modification. Triethyl phosphonoacetate can be added dropwise to sodium methoxide solution to prepare a phosphonate anion. It has an acidic proton that can easily be abstracted by a weak base.
In the related Michaelis–Arbuzov reaction the same reactants are known to form a beta-keto phosphonate which is an important reagent in the Horner–Wadsworth–Emmons reaction on the road to alkenes. The Perkow reaction, in this respect is considered a side-reaction.
Ordinarily, the Horner–Wadsworth–Emmons reaction provides the (E)-enoate (α,β-unsaturated ester), just as the Wittig reaction does. To obtain the (Z)-enolate, the Still-Gennari modification of the Horner-Wadsworth-Emmons reaction can be used.
Leopold Horner (24 August 1911 – 5 October 2005) was a German chemist who published a modified Wittig reaction using phosphonate-stabilized carbanions now called the Horner–Wadsworth–Emmons reaction (HWE reaction) or Horner-Wittig reaction.
Molecular simplification began first by disconnecting both carbon chains with a Wittig reaction and Horner-Wadsworth Emmons modification. The Wittig reaction affords the cis product, while the Horner-Wadsworth Emmons produces the trans olefin. The published synthesis reveals a 1:1 diastereomeric mixture of the carbonyl reduction using zinc ...
Réaction de Horner-Wadsworth-Emmons; Usage on it.wikipedia.org Reazione di Horner-Wadsworth-Emmons; Usage on it.wikibooks.org Chimica organica/Cose da fare; Usage on ja.wikipedia.org ホーナー・ワズワース・エモンズ反応; Usage on nl.wikipedia.org Horner-Wadsworth-Emmons-reactie; Usage on pt.wikipedia.org Reação de Horner ...