反应详情

温度

100 °C

A solution of crude product of Example 3a (6.36 g, 32.4 mmol) in toluene (11 mL) (15.7 g) was added 85% phosphoric acid (12 mL). The mixture was heated to 100° C. for 4 hours. The reaction mixture was cooled to room temperature and toluene (12 mL) along with water (24 mL) was added and the layers were separated. The aqueous layer was extracted with toluene (12 mL×2). The combined organic layers were washed with saturated aqueous sodium bicarbonate (50 mL×2) and brine (50 mL×2). Concentration and distillation under reduced pressure (b.p. 65-70° C.) afforded the title compound as a 9:1 mixture of epimers as a colorless oil (2.51 g, Yield: 50%). 1H NMR (400 MHz, CDCl3) (Major) δ 9.63 (d, J=5.2 Hz, 1H), 2.03-1.91 (m, 1H), 1.83-1.75 (m, 1H), 1.64-1.60 (m, 1H), 1.54-1.48 (m, 1H), 1.40-1.35 (m, 1H), 1.24-1.14 (m, 1H), 1.02 (s, 3H), 0.97 (s, 3H), 0.95-0.84 (m, 2H), 0.81 (d, J=6.4 Hz, 3H) ppm. [α]D24=+5.20° (c=1.00, dichloromethane).

1. temperatureThe reaction mixture was cooled to room temperature
2. customthe layers were separated
3. extractionThe aqueous layer was extracted with toluene (12 mL×2)
4. washThe combined organic layers were washed with saturated aqueous sodium bicarbonate (50 mL×2) and brine (50 mL×2)
5. concentrationConcentration and distillation under reduced pressure (b.p. 65-70° C.)