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The alkylphosphonium salt is deprotonated with a strong base such as n-butyllithium: [Ph 3 P + CH 2 R]X − + C 4 H 9 Li → Ph 3 P=CHR + LiX + C 4 H 10. Besides n-butyllithium (n BuLi), other strong bases like sodium and potassium t-butoxide (t BuONa, t BuOK), lithium, sodium and potassium hexamethyldisilazide (LiHMDS, NaHMDS, KHDMS, where HDMS = N(SiMe 3) 2), or sodium hydride (NaH) are also ...
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 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 ...
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.
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 alcohol reaction can also be used to form glycosidic bonds. [7] Similarly, an acid can be used in the place of an alcohol to form the anhydride, although dicyclohexylcarbodiimide is a more typical reagent. The equilibrium can be shifted in the favor of the anhydride by utilizing an acid in a 2:1 ratio that forms an insoluble salt with the ...
The mechanism of the aza-Wittig reaction is analogous to that of the Wittig reaction, with the Wittig reagent replaced by an iminophosphorane. [1] Mechanism of Aza-Wittig-reaction. In some cases, the iminophosphorane is not isolated but generated in situ. In this manifestation, the phosphine, carbonyl, and organic azide are combined
NaHMDS is used as a strong base in organic synthesis. Typical reactions: To deprotonate ketones and esters to generate enolate derivatives. [3] Generate carbenes by dehydrohalogenation of halocarbons. These carbene reagents add to alkenes to give substituted cyclopropanes and cyclopropenes. [4] To deprotonation of phosphonium salts, generating ...