Search results
Results From The WOW.Com Content Network
The Wittig reaction or Wittig olefination is a chemical reaction of an ... E. Vedejs has put forth a theory to explain the stereoselectivity of stabilized and ...
The [1,2]-Wittig rearrangement, which produces isomeric pent-5-en-1-ols, is a competitive process that takes place at high temperatures. [2] Because of the high atom economy and stereoselectivity of the [2,3]-rearrangement, it has gained considerable synthetic utility.
An example of modest stereoselectivity is the dehydrohalogenation of 2-iodobutane which yields 60% trans-2-butene and 20% cis-2-butene. [5] Since alkene geometric isomers are also classified as diastereomers, this reaction would also be called diastereoselective.
2,3-sigmatropic rearrangements can offer high stereoselectivity. At the newly formed double bond there is a strong preference for formation of the E-alkene or trans isomer product. The stereochemistry of the newly formed C-C bond is harder to predict. It can be inferred from the five-membered ring transition state.
The Horner–Wadsworth–Emmons (HWE) reaction is a chemical reaction used in organic chemistry of stabilized phosphonate carbanions with aldehydes (or ketones) to produce predominantly E-alkenes. [1] The Horner–Wadsworth–Emmons reaction. In 1958, Leopold Horner published a modified Wittig reaction using phosphonate-stabilized carbanions.
A 1,2-Wittig rearrangement is a categorization of chemical reactions in organic chemistry, and consists of a 1,2-rearrangement of an ether with an alkyllithium compound. [1] The reaction is named for Nobel Prize winning chemist Georg Wittig. [2] [3] The intermediate is an alkoxy lithium salt, and the final product an alcohol.
In organic chemistry, a rearrangement reaction is a broad class of organic reactions where the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. [1] Often a substituent moves from one atom to another atom in the same molecule, hence these reactions are usually intramolecular.
The difference of results between halogen exchange and E-vinyl ether reaction is that only when there is a presence of an oxonium intermediate, is isomerization observed. Marek's group zirconium vinyl iodide synthesis from vinyl ether Scheme 2. An interesting substitution reaction is vinyl boronic acid to vinyl iodide done by Brown's group. [17]