Methoxymethylenetriphenylphosphorane
Chemical compound
From Wikipedia, the free encyclopedia
Methoxymethylenetriphenylphosphorane is a Wittig reagent used for the homologation of aldehydes, and ketones to extended aldehydes.[1] The reagent is generally prepared and used in situ. It has blood-red color, indicative of destabilized ylides.
| |
| Names | |
|---|---|
| IUPAC name
Methoxymethylidene(triphenyl)-λ5-phosphane | |
| Identifiers | |
3D model (JSmol) |
|
| ChemSpider | |
PubChem CID |
|
CompTox Dashboard (EPA) |
|
| |
| |
| Properties | |
| C20H19OP | |
| Molar mass | 306.345 g·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |
Preparation
The reagent can be prepared in two steps from triphenylphosphine. The first step is P-alkylation with chloromethyl methyl ether.
- PPh3 + CH3OCH2Cl → [CH3OCH2PPh3]Cl
In the second step, the resulting phosphonium salt is deprotonated.
- [CH3OCH2PPh3]Cl + LiNR2 → CH3OCH=PPh3 + LiCl + HNR2
In place of chloromethyl methyl ether, a mixture of methylal and acetyl chloride can be used.
Wittig–Levine reaction
The use of this chemical as a Wittig reagnt to homologate alehydes and ketones was first reported by Samuel Levine[1] and this process is now sometimes called the Wittig–Levine reaction[2] or the Wittig–Levine homologation[3] The initial product of the Wittig reaction is an enol ether, which can be converted to the aldehyde by acid-catalyzed hydrolysis.
The initial report of the reaction demonstrated its use on the steroid tigogenone.[1]
It was later used in the Wender Taxol total synthesis and the Stork quinine total synthesis.