Réaction #981679

Équation de réaction

ethyl acetate

24,24-difluoro-5β-cholestane-3α,25-diol

N-bromoacetamide

→

4β-bromo-24,24-difluoro-25-hydroxy-5β-cholestan-3-one

Solvants

tert-butyl alcohol

water

hydrobromic acid

Conditions de réaction

Traitement

1. 1
   Lavagewas then washed sequentially with 0.5% aqueous sodium thiosulfate and saturated aqueous sodium chloride
2. 2
   Séchagedried over anhydrous magnesium sulfate
3. 3
   workup.DISTILLATIONThe solvent was distilled off
4. 4
   Autrethe resulting residue was purified through a short column (5 g of silica gel)
5. 5
   Autreto produce 950 mg of a crude product
6. 6
   AutreThe product was recrystallized from ether/hexane

Mode opératoire

To a solution of 800 mg of 24,24-difluoro-5β-cholestane-3α,25-diol (Va) in 32 ml of tert-butyl alcohol, 15 ml of water, 200 μl of 48% hydrobromic acid and 800 mg of N-bromoacetamide were added. After stirring at room temperature for 3 days, ethyl acetate was added to the reaction mixture, which was then washed sequentially with 0.5% aqueous sodium thiosulfate and saturated aqueous sodium chloride, and dried over anhydrous magnesium sulfate. The solvent was distilled off, and the resulting residue was purified through a short column (5 g of silica gel) to produce 950 mg of a crude product. The product was recrystallized from ether/hexane to produce 4β-bromo-24,24-difluoro-25-hydroxy-5β-cholestan-3-one.

Source