反应详情

温度

-40 °C

5.81 g of sodium borohydride are introduced into a solution of 9.5 g of the ketone prepared in Example (23c) in 307 ml of absolute methanol cooled to -40° C. and the mixture is stirred at that temperature for 3 hours. Excess sodium borohydride is then removed by adding 9.62 ml of glacial acetic acid and the mixture is concentrated to dryness at 30° C. in vacuo. Water is added to the residue and the solution is extracted several times with methylene chloride. The combined organic phases are washed with semi-saturated sodium chloride solution, dried over magnesium sulphate and concentrated. To separate the epimeric alcohols, the crude product (9.75 g) is carefully chromatographed on silica gel by gradient elution in pentane/ether. 4.4 g of the title compound are obtained.

1. customExcess sodium borohydride is then removed
2. additionby adding 9.62 ml of glacial acetic acid
3. concentrationthe mixture is concentrated to dryness at 30° C. in vacuo
4. additionWater is added to the residue
5. extractionthe solution is extracted several times with methylene chloride
6. washThe combined organic phases are washed with semi-saturated sodium chloride solution
7. dry with materialdried over magnesium sulphate
8. concentrationconcentrated
9. customTo separate the epimeric alcohols
10. customthe crude product (9.75 g) is carefully chromatographed on silica gel by gradient elution in pentane/ether