Methoxymethylenetriphenylphosphorane
Names
IUPAC name
Methoxymethylidene(triphenyl)-λ5 -phosphane
Identifiers
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
C 20 H 19 O P
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).
Chemical compound
Methoxymethylenetriphenylphosphorane is a Wittig reagent used for the homologization of aldehydes , and ketones to extended aldehydes, a organic reaction first reported in 1958.[1] The reagent is generally prepared and used in situ. It has blood-red color, indicative of destabilized ylides .
Preparation
The reagent can be prepared in two steps from triphenylphosphine . The first step is P -alkylation with chloromethyl methyl ether .
PPh3 + CH3 OCH2 Cl → [CH3 OCH2 PPh3 ]Cl
In the second step, the resulting phosphonium salt is deprotonated .
[CH3 OCH2 PPh3 ]Cl + LiNR2 → CH3 OCH=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.[2]
It was later used in the Wender Taxol total synthesis and the Stork quinine total synthesis .
References
^ A new aldehyde synthesis Samuel G. Levine J. Am. Chem. Soc. ; 1958 ; 80(22); 6150–6151. doi:10.1021/ja01555a068