Réaction #42653

Équation de réaction

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

HCl

→

(11β,16β)-9-fluoro-11,21-dihydroxy-16-methyl-3,20-dioxopregna-1,4-dien-17-yl ethylcarbamate

Rendement 50.0%

Solvants

—

pre-mixed solution

methanol chloroform

Conditions de réaction

Traitement

1. 1
   workup.WAITAfter 5 hours more
2. 2
   Autrethe solution was partitioned between ethyl acetate and water
3. 3
   LavageThe organic phase was washed successively with sat. NaHCO3, water, and brine
4. 4
   SéchageThe organic layer was dried over Na2SO4
5. 5
   Filtrationfiltered
6. 6
   Autreevaporated in vacuo
7. 7
   Autreto give a pale yellow oil
8. 8
   AutrePurification by flash chromatography through a column of 500 g of silica gel
9. 9
   Lavageeluting with hexane/ethyl acetate/dichloromethane/methanol (3:3:3:1)

Mode opératoire

Solid (11β,16β)-21-(acetyloxy)-9-fluoro-16-methyl-3,20-dioxo-11-[(trimethylsilyl)oxy]-pregna-1,4-dien-17-yl ethylcarbamate (2.22 g, 3.84 mmol) was dissolved in 128 mL of a pre-mixed solution of methanol/chloroform/6N HCl (10:2:1) and stirred at room temperature. After 16 hours, an additional 2 mL of 6N HCl was added. After 5 hours more, the solution was partitioned between ethyl acetate and water. The organic phase was washed successively with sat. NaHCO3, water, and brine. The organic layer was dried over Na2SO4, filtered and evaporated in vacuo to give a pale yellow oil. Purification by flash chromatography through a column of 500 g of silica gel, eluting with hexane/ethyl acetate/dichloromethane/methanol (3:3:3:1) yielded 0.890 g of (11β,16β)-9-fluoro-11,21-dihydroxy-16-methyl-3,20-dioxopregna-1,4-dien-17-yl ethylcarbamate as a white powder.

Source