反应详情

p-Toluenesulfonic acid (31.16 g, 164 mmol) was added to a solution of ketal (2, 23.0 g, 126 mmol) in acetone (2.3 L) and water (138 mL). The reaction mixture was heated to reflux and maintained at reflux for 3.5 h. The mixture was cooled to room temperature, treated with saturated sodium bicarbonate (60 mL) and concentrated under vacuum. The resulting oily residue was extracted with ethyl acetate (2×130 mL), washed with water (100 mL), then brine (100 mL), and dried over sodium sulfate. The filtered organic layer was concentrated under vacuum to give an oil. Weight: 16 g. Weight yield: 92%. 1H-NMR (400 MHz, CDCl3): δ 1.69 (s, 6H), 2.35 (t, 4H), 2.50 (t, 4H). MS (APCI method): No molecular ion peak was observed (Note: 1H-NMR showed the presence of ˜2% of ketal 2 but used without purification).

1. temperatureThe reaction mixture was heated
2. temperatureto reflux
3. temperaturemaintained
4. temperatureat reflux for 3.5 h
5. concentrationconcentrated under vacuum
6. extractionThe resulting oily residue was extracted with ethyl acetate (2×130 mL)
7. washwashed with water (100 mL)
8. dry with materialbrine (100 mL), and dried over sodium sulfate
9. concentrationThe filtered organic layer was concentrated under vacuum
10. customto give an oil
11. customused without purification)