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The Wittig reaction or Wittig olefination is a chemical reaction of an aldehyde or ketone with a triphenyl phosphonium ylide called a Wittig reagent. Wittig reactions are most commonly used to convert aldehydes and ketones to alkenes. [1] [2] [3] Most often, the Wittig reaction is used to introduce a methylene group using ...
Because phosphonium ylides are seldom isolated, the byproduct(s) generated upon deprotonation essentially plays the role of an additive in a Wittig reaction. As a result, the choice of base has a strong influence on the efficiency and, when applicable, the stereochemical outcome of the Wittig reaction.
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.
The [2,3]-Wittig rearrangement is the transformation of an allylic ether into a homoallylic alcohol via a concerted, pericyclic process.Because the reaction is concerted, it exhibits a high degree of stereocontrol, and can be employed early in a synthetic route to establish stereochemistry.
Georg Wittig (German: [ˈɡeː.ɔʁk ˈvɪ.tɪç] ⓘ; 16 June 1897 – 26 August 1987) was a German chemist who reported a method for synthesis of alkenes from aldehydes and ketones using compounds called phosphonium ylides in the Wittig reaction.
For example, the reaction of triphenylphosphine with methyl bromide gives methyltriphenylphosphonium bromide: PPh 3 + CH 3 Br → [CH 3 PPh 3] + Br −. The methyl group in such phosphonium salts is mildly acidic, with a pK a estimated to be near 15: [5] [CH 3 PPh 3] + + base → CH 2 =PPh 3 + [Hbase] + This deprotonation reaction gives Wittig ...
It can be produced by a Wittig reaction or a reaction with a Tebbe's reagent from cyclohexanone. [ 1 ] [ 2 ] [ 3 ] It can also be synthesized as a side product of the dehydration of 2-methylcyclohexanol into 1-methylcyclohexene.
2 Reactions. 3 References. Toggle the table of contents. ... It undergoes a Wittig reaction. [1] It is used in the Vitamin B12 total synthesis. Production