反应详情

The product of Example 3A (23.2 g) was dissolved in ethyl acetate (250 mL) and p-toluenesulfonic acid monohydrate (11.4 g, 60 mmol) was added. The solution was warmed to reflux and stirred for 90 minutes, cooled to room temperature, and allowed to stand for 12 hours to complete precipitation. The solid was isolated by filtration and dried to provide the title compound. mp 174–178° C.; [α]D20=−20.0° (MeOH, 0.105); 1H NMR (MeOH-d4, 300 MHz) δ 2.36 (s, 3H), 3.06 (dd, J=10.5, 6.1 Hz, 1H), 3.17 (dd, J=12.2, 4.8 Hz, 1H), 3.50 (m, 1H), 3.72 (dd, J=11.2, 5.4 Hz, 1H), 3.90 (d, J=10.5 Hz, 1H), 4.10 (d, J=12.6 Hz, 1H), 4.25 (dd, J=11.2, 9.8 Hz, 1H), 5.05 (dd, J=6.7, 5.1 Hz, 1H) 7.22 (d, J=8.1 Hz, 2H), 7.52 (d, J=2.7 Hz, 1H), 7.69 (d, J=8.1 Hz, 2H), 7.95 (d, J=2.7 Hz, 1H); MS (DCI/NH3) m/z 244/246/248 (M+H)+.

1. temperatureThe solution was warmed
2. temperatureto reflux
3. waitto stand for 12 hours
4. customprecipitation
5. customThe solid was isolated by filtration
6. customdried