Reaction #5353

Reaction equation

8-carbomethoxyoctanal

4-chlorobenzyltriphenylphosphonium chloride

water

potassium hexamethyldisilazide

→

10-(4-chlorophenyl)-dec-9-enoic acid methyl ester

Yield 13.0%

Solvents

tetrahydrofuran

tetrahydrofuran

Conditions

Workup

1. 1
   workup.ADDITIONis added dropwise
2. 2
   Temperatureto warm to room temperature
3. 3
   workup.STIRRINGstirred for 2 days
4. 4
   Extractionextracting three times with diethyl ether
5. 5
   Washwashed with brine
6. 6
   Dryingdried over Na2SO4
7. 7
   Filtrationfiltered
8. 8
   Concentrationconcentrated in vacuo
9. 9
   Otherto give a yellow solid
10. 10
    FiltrationPad filtration through flash silica gel eluting with 10% ethyl acetate/hexane
11. 11
    Othergives a yellow oil
12. 12
    Concentrationafter concentration in vacuo
13. 13
    WashFlash chromatography on a 60 mm×150 mm silica column eluting with 5% ethyl acetate/hexane

Procedure

To a solution of 18.2 g (43 mmol) of 4-chlorobenzyltriphenylphosphonium chloride in 200 mL of dry tetrahydrofuran at -78° C. is added dropwise, 30.7 mL (43 mmol) of a 1.4M solution of potassium hexamethyldisilazide in tetrahydrofuran. This is allowed to stir for 1 hour when 8.0 g (43 mmol) of 8-carbomethoxyoctanal is added dropwise. The solution is stirred at -78° C. for 2 hours, allowed to warm to room temperature, and stirred for 2 days. The reaction is worked up by adding water and extracting three times with diethyl ether. The ether extracts are combined, washed with brine, dried over Na2SO4, filtered, and concentrated in vacuo to give a yellow solid. Pad filtration through flash silica gel eluting with 10% ethyl acetate/hexane, gives a yellow oil after concentration in vacuo. Flash chromatography on a 60 mm×150 mm silica column eluting with 5% ethyl acetate/hexane gives 1.62 g (13%) of 10-(4-chlorophenyl)-dec-9-enoic acid methyl ester as a mixture of E and Z isomers.

Source