反应详情

The product from Step 1 (7.0 g, 18.7 mmol) was dissolved in acetonitrile (200 mL) and stirred at ambient temperature while ceric ammonium nitrate (32 g, 58 mmol) in water (60 mL) was added in portions over 10 min. The solution was then heated to reflux for 4 h, cooled, and diluted with water (200 mL). The solution was extracted with ether (2×200 mL), and the combined organic layer was dried and concentrated to give an orange oil. This material was dissolved in dioxane (40 mL) and treated with a solution of KOH (5 g, 90 mmol) in water (20 mL). The solution was heated to reflux for 2 h, then cooled and diluted with water (100 mL). The aldehyde precipitated and was collected by filtration. Recrystallization from MeOH/H2O gave the pure aldehyde as a white solid (2.2 g, 30%): mp 137-144° C. 1H NMR (300 MHz, CDCl3) δ 10.1 (s, 1H), 8.65 (s, 1H), 8.40 (d, J=8.4 Hz, 2H), 8.0 (d, J=8.4 Hz, 2H), 7.85 (d, J=9 Hz, 2H), 7.45 (d, J=9 Hz, 2H); ESIMS m/z 384.2 (M+H).

1. additionwas added in portions over 10 min
2. temperatureThe solution was then heated
3. temperatureto reflux for 4 h
4. temperaturecooled
5. extractionThe solution was extracted with ether (2×200 mL)
6. customthe combined organic layer was dried
7. concentrationconcentrated
8. customto give an orange oil
9. temperatureThe solution was heated
10. temperatureto reflux for 2 h
11. temperaturecooled
12. customThe aldehyde precipitated
13. filtrationwas collected by filtration
14. customRecrystallization from MeOH/H2O