Reaktion #42651

Reaktionsgleichung

acetic acid

(11β,16β)-9-fluoro-16-methyl-3,20-dioxo-11,17-bis[(trimethylsilyl)oxy]pregna-1,4-dien-21-yl acetate

tetra-n-butylammonium fluoride

→

title compound

Ausbeute 73.9%

(11β,16β)-9-fluoro-17-hydroxy-16-methyl-3,20-dioxo-11-[(trimethylsilyl)oxy]-pregna-1,4-dien-21-yl acetate

Ausbeute 73.9%

Lösungsmittel

tetrahydrofuran

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigethe ice bath was removed
2. 2
   Temperaturto warm to room temperature
3. 3
   workup.STIRRINGstir for an additional 16 hours
4. 4
   SonstigeMost of the THF was removed by rotary evaporation in vacuo
5. 5
   Sonstigethe residue was partitioned between ethyl acetate and water
6. 6
   WaschenThe organic layer was washed successively with water, sat. NH4Cl, water, sat. NaHCO3, water and brine
7. 7
   TrocknenThe organic layer was dried over Na2SO4
8. 8
   Filtrationfiltered
9. 9
   Sonstigeevaporated under vacuum
10. 10
    Sonstigeto give an off-white solid
11. 11
    SonstigePurification by flash chromatography through a 1.6 kg column of silica gel eluting with 4% MeOH in dichloromethane

Vorschrift

A solution of (11β,16β)-9-fluoro-16-methyl-3,20-dioxo-11,17-bis[(trimethylsilyl)oxy]pregna-1,4-dien-21-yl acetate (26 g, ˜43 mmol) in 430 mL of tetrahydrofuran (THF) was cooled to 0° C. and neat acetic acid (4.95 mL, 86.5 mmol) was added followed by dropwise addition of a 1.0 M solution of tetra-n-butylammonium fluoride in THF (43.3 mL, 43.3 mmol). After stirring at 0° C. for 4 hours, the ice bath was removed and the reaction was allowed to warm to room temperature and stir for an additional 16 hours. Most of the THF was removed by rotary evaporation in vacuo and the residue was partitioned between ethyl acetate and water. The organic layer was washed successively with water, sat. NH4Cl, water, sat. NaHCO3, water and brine. The organic layer was dried over Na2SO4, filtered and evaporated under vacuum to give an off-white solid. Purification by flash chromatography through a 1.6 kg column of silica gel eluting with 4% MeOH in dichloromethane provided 16.1 g of the title compound as a white solid.

Quelle