Reaction #213890

Reaction equation

magnesium

propargyl bromide

1,1-dimethoxy-2-hexanone

imidazole

trimethylchlorosilane

1,2-dibromoethane

ammonium chloride

magnesium sulfate

→

title compound

4-Dimethoxymethyl-4-trimethylsiloxy-1-octyne

Solvents

ether

tetrahydrofuran

water

ether

ether

Conditions

Workup

1. 1
   workup.ADDITIONTo a suspension of 5.31 g
2. 2
   workup.ADDITIONfollowed by the dropwise addition of a solution of 25 g
3. 3
   workup.ADDITIONMidway through the addition 15 ml
4. 4
   workup.ADDITIONAfter complete addition of the solution
5. 5
   Temperaturethe mixture is refluxed for 40 minutes
6. 6
   FiltrationThe mixture is filtered through Celite
7. 7
   Otherthe solvent is removed
8. 8
   workup.DISSOLUTIONThe residue is dissolved in 53 ml
9. 9
   workup.ADDITIONof dimethylformamide and at 0° C. is added 24.4 g
10. 10
    Extractionextracted with hexanes
11. 11
    DryingThe organic layer is dried over magnesium sulfate
12. 12
    Otherthe solvent is removed
13. 13
    workup.DISTILLATIONDistillation (75°-95° C., 0.3 mm.)
14. 14
    Othergives 17.4 g

Procedure

To a suspension of 5.31 g. (0.22 moles) of magnesium in 15 ml. of ether is added 100 mg. of mercuric chloride and 1.5 ml. of 1,2-dibromoethane. After the reaction begins, another 45 ml. of ether is added followed by the dropwise addition of a solution of 25 g. (0.16 moles of 1,1-dimethoxy-2-hexanone and 27.3 g. (0.2 moles) of 85% propargyl bromide in 45 ml. of ether at a rate which maintains reflux. Midway through the addition 15 ml. of tetrahydrofuran is added. After complete addition of the solution, the mixture is refluxed for 40 minutes. The mixture is cooled to 0° C. and saturated ammonium chloride solution is added followed by magnesium sulfate. The mixture is filtered through Celite and the solvent is removed. The residue is dissolved in 53 ml. of dimethylformamide and at 0° C. is added 24.4 g. (0.36 moles) of imidazole and 21.19 g. (0.20 moles) of trimethylchlorosilane. After stirring at 25° C. for 70 minutes, the solution is poured into water and extracted with hexanes. The organic layer is dried over magnesium sulfate and the solvent is removed. Distillation (75°-95° C., 0.3 mm.) gives 17.4 g. of the title compound.

Source