反应详情

A solution of crude 37 (2.23 mmol) in toluene (80 mL) was treated with p-toluenesulfonic acid (100 mg) and refluxed under a Dean-Stark trap for 3 hr. After cooling, the reaction mixture was diluted with ethyl acetate (150 mL) and washed with saturated sodium bicarbonate (150 mL) and water (2×100 mL). The organic extract was dried over sodium sulfate and filtered. The solvent was removed in a rotary evaporator and the crude product was purified by chromatography on silica (75 g) with 2% ethyl acetate in heptane (4 L) to afford 38 (0.78 g, 78%).

1. temperaturerefluxed under a Dean-Stark trap for 3 hr
2. temperatureAfter cooling
3. washwashed with saturated sodium bicarbonate (150 mL) and water (2×100 mL)
4. extractionThe organic extract
5. dry with materialwas dried over sodium sulfate
6. filtrationfiltered
7. customThe solvent was removed in a rotary evaporator
8. customthe crude product was purified by chromatography on silica (75 g) with 2% ethyl acetate in heptane (4 L)