反应详情

4,4-Dimethyl-17β-tert-butyldimethylsilyloxyandrost-5-en-3-one (4.0 g) was dissolved in toluene (235 ml). Ethylene glycol (9.3 ml) and PTSA (124 mg) were added and the mixture was refluxed for 7.5 h, removing water with a Dean-Stark trap. After cooling, water was added and the mixture was extracted with EtOAc. The organic phase was washed with 5% NaHCO3, brine then dried over Na2SO4 and evaporated to dryness to give 3,3-(ethylenedioxy)-4,4-dimethyl-17β-tert-butyldimethylsilyloxy-androst-5-ene (4.4 g, 100%) which was used without purification in the next step.

1. temperaturethe mixture was refluxed for 7.5 h
2. customremoving water with a Dean-Stark trap
3. temperatureAfter cooling
4. additionwater was added
5. extractionthe mixture was extracted with EtOAc
6. washThe organic phase was washed with 5% NaHCO3, brine
7. dry with materialthen dried over Na2SO4
8. customevaporated to dryness