Reaction #42653

Reaction equation

(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

Yield 50.0%

Solvents

—

pre-mixed solution

methanol chloroform

Conditions

Workup

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

Procedure

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