Search results
Results from the WOW.Com Content Network
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.
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.
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.
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.
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.
Wittig–Horner reaction; Wohl degradation; Wohl–Aue reaction; Wohler synthesis; Wohl–Ziegler reaction; Wolffenstein–Böters reaction; Wolff rearrangement; Wolff–Kishner reduction; Woodward cis-hydroxylation; Woodward–Hoffmann rule; Wulff–Dötz reaction; Wurtz coupling, Wurtz reaction; Wurtz–Fittig reaction
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 ...
The rule states that with the addition of a protic acid HX or other polar reagent to an asymmetric alkene, the acid hydrogen (H) or electropositive part gets attached to the carbon with more hydrogen substituents, and the halide (X) group or electronegative part gets attached to the carbon with more alkyl substituents.