反应详情

Ethyl 5-(9-oxoxanthen-2-oxy)valerate (7.0 g, 21 mmol) prepared as described above was suspended in 95% EtOH (50 mL), and 4 N aqueous NaOH (50 mL, 0.2 mmol) was added. The reaction mixture was homogeneous within 1h, and saponification proceeded at 25° C. for a total of 4 h. Subsequently, 12 N aqueous HCl (17 mL) was added with cooling to adjust the pH to 3. A light-gray precipitate formed, which was collected, washed with water (3×10 mL), and dried in vacuo over P2O5, to give the free acid product. Yield: 6.1 g (94%). A small amount of the product was recrystallized from n-hexane-EtOH (10:1) for elemental analysis in accordance with structure. Light beige needles, m.p. 151-152° C.

1. customproceeded at 25° C. for a total of 4 h
2. temperaturewith cooling
3. customA light-gray precipitate formed
4. customwhich was collected
5. washwashed with water (3×10 mL)
6. dry with materialdried in vacuo over P2O5
7. customto give the free acid product
8. customA small amount of the product was recrystallized from n-hexane-EtOH (10:1) for elemental analysis in accordance with structure