Reaktion #95296

Reaktionsgleichung

diborane

bromine

4,4-dimethyl-3-tetrahydropyranyloxy-1-octyne

2-methyl-2-butene

→

title compound

1-bromo-4,4-dimethyl-3-tetrahydropyranyloxy-trans-1-octene

Lösungsmittel

tetrahydrofuran

tetrahydrofuran

carbon tetrachloride

carbon tetrachloride

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigethe solvent is removed under vacuum
2. 2
   workup.DISSOLUTIONThe residue is dissolved in 20 ml
3. 3
   workup.ADDITIONis added a solution of 5.25 g
4. 4
   SonstigeThe cooling bath is removed
5. 5
   workup.STIRRINGto stir at ambient temperature for 1.5 hours
6. 6
   TemperaturThe mixture is cooled to 0° C.
7. 7
   SonstigeThe cooling bath is removed
8. 8
   Temperaturthe mixture is refluxed for 6 hours under an inert atmosphere
9. 9
   TemperaturThe mixture is cooled
10. 10
    workup.ADDITIONpoured into dilute sodium hydroxide solution
11. 11
    WaschenThe organic phase is washed with water and saturated brine
12. 12
    Trocknendried (Na2SO4)
13. 13
    Sonstigeevaporated
14. 14
    SonstigeThe residue is chromatographed upon silica gel

Vorschrift

To an ice cooled solution of 3.5 g. (50 moles) of 2-methyl-2-butene in 25 ml. of tetrahydrofuran under an inert atmosphere is added 25 ml. of 1 M diborane in tetrahydrofuran dropwise over 10 minutes. The mixture is stirred at 0°-5° C. for 2 hours and then the solvent is removed under vacuum. The residue is dissolved in 20 ml. of carbon tetrachloride and to the resulting solution cooled to 0° C. is added a solution of 5.25 g. (22 mole) of 4,4-dimethyl-3-tetrahydropyranyloxy-1-octyne (Example 995) in 10 ml. of carbon tetrachloride over 10 minutes. The cooling bath is removed and the mixture is allowed to stir at ambient temperature for 1.5 hours. The mixture is cooled to 0° C. and a solution of 3.52 g. (22 moles) of bromine in 15 ml. of carbon tetrachloride is added over 10 minutes. The cooling bath is removed and the mixture is refluxed for 6 hours under an inert atmosphere. The mixture is cooled and poured into dilute sodium hydroxide solution. The organic phase is washed with water and saturated brine, dried (Na2SO4), and evaporated. The residue is chromatographed upon silica gel and the title compound is isolated with 5% ethyl acetate in benzene.

Quelle