反应详情

In a 250 ml flask, equipped with a magnetic stirrer, 1.8 g of the diol (6C, R=menthyl) from the Step 2 of Example 4 (fast moving diastereomer) was dissolved in 50 ml of 2,2-dimethoxypropane at room temperature. Then, 100 mg of paratoluenesulfonic acid monohydrate was added, and the resulting mixture was stirred at room temperature for 18 hours. Then, 100 ml of ethyl acetate and 100 ml of saturated aqueous NaHCO3 were added. The aqueous phase was extracted with 100 ml of ethyl acetate. The combined organic layers were washed with 100 ml of brine, dried (Na2SO4) and concentrated at reduced pressure. The crude product was purified by column chromatography (Merck60 SiO2; eluens=ethyl acetate/heptane=1/4) to give the acetonide (8, R=menthyl) (1.855 g; 92%) as a colourless oil. 1H-NMR and 13C-NMR confirmed the structure

1. customIn a 250 ml flask, equipped with a magnetic stirrer
2. extractionThe aqueous phase was extracted with 100 ml of ethyl acetate
3. washThe combined organic layers were washed with 100 ml of brine
4. dry with materialdried (Na2SO4)
5. concentrationconcentrated at reduced pressure
6. customThe crude product was purified by column chromatography (Merck60 SiO2; eluens=ethyl acetate/heptane=1/4)