反应详情

温度

-55 °C

A solution of 500 mg of 11β-fluoro-7α-methylestr-4-ene-3,17-dione (B′) in 10 ml of tetrahydrofuran, 5.8 ml of ethanol and 1.15 ml of water was stirred at −55° C. with 175.6 mg of sodium borohydride for 2.5 hours. After another 351.2 mg of sodium borohydride was added, it was stirred for another 1.5 hours at −55° C., then added to ice water, extracted three times with ethyl acetate, washed neutral, dried on sodium sulfate and concentrated by evaporation in a vacuum. Then, it was chromatographed on silica gel with hexane/ethyl acetate. 230 mg of pure 11β-fluoro-17β-hydroxy-7α-methylestr-4-en-3-one (I) with a melting point of 126.7° C. was obtained ([α]D20=+79.9° (c=0.53% in chloroform)).

1. extractionextracted three times with ethyl acetate
2. washwashed neutral
3. customdried on sodium sulfate
4. concentrationconcentrated by evaporation in a vacuum
5. customThen, it was chromatographed on silica gel with hexane/ethyl acetate