反应详情

A mixture of (6) (1.71 g, 5.25 mmol), ethylene glycol (0.88 ml, 15.75 mmol), and p-toluenesulfonic acid (263 mg, 0.26 mmol) in toluene (20 ml) was refluxed for 3 hr., using a reflux condenser equipped with a Dean-Stark trap. After cooling to room temperature, the mixture was diluted with EA, washed with aqueous saturated sodium bicarbonate solution, dried with anhydrous magnesium sulfate, filtered, and evaporated in vacuo. The residue was purified by silica gel column chromatography (eluent, EA:hexanes (1:15)) to afford 1.79 g (92%) of a colorless syrup; 1H NMR (200 MHz, CDCl3) δ 1.40 (6H, d, J=7.0 Hz), 2.40 (3H, s), 3.58 (1H, m), 3.99-4.16 (4H, m), 5.82 (1H, s), 6.92 (1H, s), 7.03 (1H, s), 7.21 (1H, s).

1. temperaturewas refluxed for 3 hr
2. customequipped with a Dean-Stark trap
3. washwashed with aqueous saturated sodium bicarbonate solution
4. dry with materialdried with anhydrous magnesium sulfate
5. filtrationfiltered
6. customevaporated in vacuo
7. customThe residue was purified by silica gel column chromatography (eluent, EA:hexanes (1:15))