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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.
For stabilized Wittig reagents bearing conjugated electron-withdrawing groups, even relatively weak bases like aqueous sodium hydroxide or potassium carbonate can be employed. [Ph 3 PCH 3] + Br −, typical phosphonium salt. The identification of a suitable base is often an important step when optimizing a Wittig reaction.
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 ...
Sodium amide has also been used a base. [4] Methylenetriphenylphosphorane is used to replace oxygen centres in aldehydes and ketones with a methylene group, i.e., a methylenation: R 2 CO + Ph 3 PCH 2 → R 2 C=CH 2 + Ph 3 PO. The phosphorus-containing product is triphenylphosphine oxide.
It undergoes a Wittig reaction. [1] ... This makes a phosphonium salt, which is converted to the final product by sodium carbonate in water. [1] Reactions
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.
Most of this article is about the homogeneous (one-phase) reaction of preformed organolithium compounds: R−Li + R′−X → R−X + R′−Li. Butyllithium is commonly used. Gilman and Wittig independently discovered this method in the late 1930s. [1] It is not a salt metathesis reaction, as no salt is produced.
Wittig reagents are used in organic synthesis. They are derived from phosphonium salts. A strong base such as butyllithium or sodium amide is required for the deprotonation: [Ph 3 P + CH 2 R]X − + C 4 H 9 Li → Ph 3 P=CHR + LiX + C 4 H 10. One of the simplest ylides is methylenetriphenylphosphorane (Ph 3 P=CH 2). [6]