Methoxymethylenetriphenylphosphorane

Methoxymethylenetriphenylphosphine is a Wittig reagent used for the homologization of aldehydes, and ketones to extended aldehydes, a organic reaction first reported in 1958. The reagent is generally prepared and used in situ. It has blood-red color, indicative of destabilized ylides.

Methoxymethylene­triphenylphosphorane
Names
IUPAC name
Methoxymethylidene(triphenyl)-λ5-phosphane
Identifiers
3D model (JSmol)
  • InChI=1S/C20H19OP/c1-21-17-22(18-11-5-2-6-12-18,19-13-7-3-8-14-19)20-15-9-4-10-16-20/h2-17H,1H3
    Key: DYROHZMICXBUMX-UHFFFAOYSA-N
  • COC=P(C1=CC=CC=C1)(C2=CC=CC=C2)C3=CC=CC=C3
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).
Infobox references

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.

Uses

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.

Titogenone homologation

It was later used in the Wender Taxol total synthesis and the Stork quinine total synthesis.

References
  1. ^ A new aldehyde synthesis Samuel G. Levine J. Am. Chem. Soc.; 1958; 80(22); 6150–6151. doi:10.1021/ja01555a068
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.