Reaktion #354809

Reaktionsgleichung

calcium carbonate

lithium bromide

2β-bromo-17β-cyano-3α-hydroxy-5α-androstane

dihydropyran

→

title compound

Ausbeute 11.0%

17β-Cyano-3α-hydroxy-5α-androst-1-ene

Ausbeute 11.0%

Lösungsmittel

chloroform

dimethylacetamide

benzene

Reaktionsbedingungen

Aufarbeitung

1. 1
   WaschenAfter 45 minutes at room temperature the solution was washed with aqueous 10% sodium bicarbonate (25 ml.) and water
2. 2
   Trocknento being dried (MgSO4)
3. 3
   Filtrationfiltered
4. 4
   Sonstigeevaporated
5. 5
   Sonstigeto give crude 2β-bromo-17β-cyano-3α-(tetrahydropyran-2'ξ-yloxy)-5α-androstane
6. 6
   Temperaturheated on an oil bath (110°) for 6 hours
7. 7
   TemperaturAfter cooling
8. 8
   Waschenwashed with water
9. 9
   Sonstigebefore drying
10. 10
    Filtration(MgSO4) filtration and evaporation to a residue which
11. 11
    workup.DISSOLUTIONwas dissolved in methanol (100 ml.)
12. 12
    SonstigeAfter 21/2 hours at room temperature and methanol was removed by evaporation
13. 13
    workup.DISSOLUTIONthe residue dissolved in chloroform (25 ml.)
14. 14
    WaschenThis solution was washed with aqueous 10% sodium bicarbonate (25 ml.) and water (25 ml.)
15. 15
    Sonstigebefore drying
16. 16
    Filtration(MgSO4), filtration and evaporation to a gum (2.55 g.)
17. 17
    WaschenA sample (1.0 g.), after preparative TLC eluting with acetone/petrol (1:2,)

Vorschrift

p-Toluenesulphonic acid (10 mg.) was added to a stirred solution of 2β-bromo-17β-cyano-3α-hydroxy-5α-androstane (2.65 g.,) and dihydropyran (10 ml.) in dry benzene (200 ml.). After 45 minutes at room temperature the solution was washed with aqueous 10% sodium bicarbonate (25 ml.) and water prior to being dried (MgSO4), filtered and evaporated to give crude 2β-bromo-17β-cyano-3α-(tetrahydropyran-2'ξ-yloxy)-5α-androstane. A mixture of calcium carbonate (15 g.), anhydrous lithium bromide (22.5 g.) and the tetrahydropyranyl derivative in dimethylacetamide (100 ml.) was stirred and heated on an oil bath (110°) for 6 hours. After cooling, the reaction mixture was diluted with chloroform and washed with water before drying (MgSO4) filtration and evaporation to a residue which was dissolved in methanol (100 ml.) and aqueous 2N hydrochloric acid (2 ml.). After 21/2 hours at room temperature and methanol was removed by evaporation and the residue dissolved in chloroform (25 ml.). This solution was washed with aqueous 10% sodium bicarbonate (25 ml.) and water (25 ml.) before drying (MgSO4), filtration and evaporation to a gum (2.55 g.). A sample (1.0 g.), after preparative TLC eluting with acetone/petrol (1:2,), afforded title compound (230 mg.,) as a white froth; [α]D 0°, (c 0.3). A sample was recrystallised from ether/petrol (x2); m.p. 129°-133°; [α]P 4°, c 0.5.

Quelle