Réaction #1552133

Équation de réaction

Jones reagent

tetrol

3α,7α,16α,24-tetrahydroxy-6α-ethyl-5β-cholane

Methanol

→

methyl ester

Methyl 3,7,16-trioxo-6α-ethyl-5β-cholan-24-oate

Solvants

acetone

Conditions de réaction

Traitement

1. 1
   Extractionthe oxidized product was extracted with EtOAc (2×50 ml)
2. 2
   SéchageThe combined organic layers were dried over anhydrous sodium sulphate
3. 3
   Autreevaporated to dryness under reduced pressure
4. 4
   workup.DISSOLUTIONThe residue was dissolved in MeOH (80 ml)
5. 5
   workup.ADDITIONpTSA was added
6. 6
   workup.STIRRINGthe mixture was stirred at room temperature for 2 h
7. 7
   AutreThe solvent was evaporated
8. 8
   workup.DISSOLUTIONthe residue was dissolved in CHCl3 (50 ml)
9. 9
   Lavagewashed with a saturated aqueous solution of sodium bicarbonate (2×50 ml), water (50 ml) and brine (50 ml)
10. 10
    SéchageThe organic layer was dried over anhydrous sodium sulfate
11. 11
    Autreevaporated to dryness
12. 12
    AutreThe residue was purified by flash chromatography

Mode opératoire

Jones reagent (2 ml) was added dropwise to a stirred solution of the tetrol 7 (0.19 g, 0.45 mmol) in acetone (25 ml) at 0° C. and the mixture was stirred at room temperature for 1 h. Methanol (8 ml) was then added and the oxidized product was extracted with EtOAc (2×50 ml). The combined organic layers were dried over anhydrous sodium sulphate and evaporated to dryness under reduced pressure. The residue was dissolved in MeOH (80 ml), pTSA was added and the mixture was stirred at room temperature for 2 h. The solvent was evaporated under reduce pressure, the residue was dissolved in CHCl3 (50 ml), washed with a saturated aqueous solution of sodium bicarbonate (2×50 ml), water (50 ml) and brine (50 ml). The organic layer was dried over anhydrous sodium sulfate and evaporated to dryness. The residue was purified by flash chromatography using from 20 to 30% EtOAc in petroleum ether to afford the methyl ester 8 (0.115 g, 0.26 mmo, 58%1) as whitish solid.

Source