Réaction #216502

Équation de réaction

n-Butyllithium

acetone N,N-dimethylhydrazone

2,2-dimethyl-5-(3-oxo9-trimethylsilylnon-8-ynyl)-5-n-propyl-1,3-dioxane

n-butyllithium

5-iodomethyl-2,2-dimethyl-5-n-propyl-1,3-dioxane

7-oxo-1-trimethylsilyloct-1-yne

5-iodo-1-trimethylsilylpent-1-yne

hydrochloric acid

→

4-n-Propyl-1-(6-trimethylsilylhex-5-ynyl)-2,6-dioxabicyclo[2.2.2]octane

Solvants

tetrahydrofuran

tetrahydrofuran

tetrahydrofuran

tetrahydrofuran

Conditions de réaction

Traitement

1. 1
   workup.STIRRINGthe reaction mixture was stirred at -70° for 1 hour
2. 2
   Températureto warm to 0°
3. 3
   workup.STIRRINGstirred for 2 hours
4. 4
   TempératureThe reaction mixture was cooled to -70°
5. 5
   workup.STIRRINGThe mixture was stirred at -70° for 15 minutes
6. 6
   Températureto warm to 0°
7. 7
   workup.STIRRINGstirred for 30 minutes
8. 8
   workup.STIRRINGThe mixture was stirred at 0° for 30 minutes and 48 hours at 20°
9. 9
   AutreThe solvent was removed in vacuo
10. 10
    workup.ADDITIONthe residue was poured into water
11. 11
    ExtractionThe aqueous mixture was extracted with diethyl ether
12. 12
    Lavagethe ethereal extracts were washed with water
13. 13
    Séchagedried over anhydrous magnesium sulphate
14. 14
    Autreevaporated in vacuo
15. 15
    LavageChromatography of the residue on silica, eluting with diethyl ether: hexane 1:9
16. 16
    Autregave a yellow oil which
17. 17
    AutreThe tetrahydro- furan was removed in vacuo
18. 18
    Extractionthe residue was extracted into diethyl ether
19. 19
    SéchageThe ethereal extracts were dried over magnesium sulphate
20. 20
    Autrethe solvent was removed in vacuo

Mode opératoire

n-Butyllithium (19.0 ml., 1.6M solution in hexane) was added dropwise to a stirred solution of acetone N,N-dimethylhydrazone (2.6 g.) (ref. R. H. Wiley et al J. Org. Chem. 1957, 22, 204) in dry tetrahydrofuran (40 ml.) at -70° , under a current of nitrogen. The resulting solution was stirred for 30 minutes and a solution of 5-iodo-1-trimethylsilylpent-1-yne (8.1 g.) in dry tetrahydrofuran (30 ml.) was added dropwise and the reaction mixture was stirred at -70° for 1 hour, allowed to warm to 0° and stirred for 2 hours. The reaction mixture was cooled to -70° and a second portion of n-butyllithium (19 ml. 1.6M solution in hexane) was added dropwise. The mixture was stirred at -70° for 15 minutes, allowed to warm to 0° and stirred for 30 minutes. A solution of 5-iodomethyl-2,2-dimethyl-5-n-propyl-1,3-dioxane (9.0 g. European Patent 216625) in dry tetrahydrofuran (30 ml.) was added. The mixture was stirred at 0° for 30 minutes and 48 hours at 20°. The solvent was removed in vacuo and the residue was poured into water. The aqueous mixture was extracted with diethyl ether and the ethereal extracts were washed with water, dried over anhydrous magnesium sulphate and evaporated in vacuo. Chromatography of the residue on silica, eluting with diethyl ether: hexane 1:9 gave a yellow oil which consisted of 2,2-dimethyl-5-(3-oxo9-trimethylsilylnon-8-ynyl)-5-n-propyl-1,3-dioxane and 7-oxo-1-trimethylsilyloct-1-yne in the ratio of 3:1 (1.4 g.). The above mixture in tetrahydrofuran (25 ml.) and hydrochloric acid (50 ml., 1N solution) was stirred vigorously at 20° for 1 hour. The tetrahydro- furan was removed in vacuo and the residue was extracted into diethyl ether. The ethereal extracts were dried over magnesium sulphate and the solvent was removed in vacuo. 4-n-Propyl-1-(6-trimethylsilylhex-5-ynyl)-2,6-dioxabicyclo[2.2.2]octane was obtained as a colourless oil (1.06 g.) and was used without further purification.

Source