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In organic chemistry, Wittig reagents are organophosphorus compounds of the formula R 3 P=CHR', where R is usually phenyl. They are used to convert ketones and aldehydes to alkenes: They are used to convert ketones and aldehydes to alkenes:
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 ...
Methylenetriphenylphosphorane is an organophosphorus compound with the formula Ph 3 PCH 2. It is the parent member of the phosphorus ylides , popularly known as Wittig reagents . It is a highly polar, highly basic species.
This reagent reacts with a ketone or aldehyde in a Wittig reaction to give an enol ether, which can be converted to the aldehyde by acid-induced hydrolysis. The initial report of the reaction demonstrated its use on the steroid tigogenone. It was later used in the Wender Taxol total synthesis and the Stork quinine total synthesis.
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.
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 Thorpe–Ingold effect may also be exploited to improve both reaction rates and product selectivity. Cross-metathesis is synthetically equivalent to (and has replaced) a procedure of ozonolysis of an alkene to two ketone fragments followed by the reaction of one of them with a Wittig reagent .
It exhibits similar reactivity to the Tebbe reagent and Wittig reaction. Unlike the Wittig reaction, the Petasis reagent can react with a wide range of aldehydes, ketones and esters. [4] The Petasis reagent is also very air stable, and is commonly used in solution with toluene or THF. The Tebbe reagent and the Petasis reagent share a similar ...