反应详情

5-Hydroxy-2,2-dimethyl-6-propionyl-10-propyl-2H-pyrano[2,3-f]chromen-8-one (30) (1.0 g, 2.9 mmol, 1.0 eq) was dissolved in 7 N ammonia in methanol (100 mL, 0.7 mol, 241 eq). The mixture was stirred overnight at ambient temperature. Solvent and excess of ammonia were removed under vacuum and the residue re-dissolved in methanol (100 mL). The solution was cooled to 0° C. and sodium borohydride (550 mg, 14.6 mmol, 5.0 eq) added portionwise. The mixture was allowed to warm up room temperature and stirred for 3 h. The mixture was then poured into ice-water and pH adjusted to 8.5 with concentrated hydrochloric acid. The product was extracted into ethyl acetate (3×50 mL). The extracts were combined and washed with brine, dried over anhydrous sodium sulfate and concentrated under vacuum. The residue was chromatographed on silica gel column eluted with 5-10% methanol in dichloromethane to yield 612 mg of 24a (61% yield). 1H NMR (CDCl3): 0.97 (t, J=7.5 Hz, 3H), 1.03 (t, J=7.5 Hz, 3H), 1.47 (s, 3H), 1.49 (s, 3H), 1.67 (m, 2H), 1.78 (m, 2H), 2.89 (m, 2H), 4.85 (t, J=7.0 Hz, 1H), 5.52 (d, J=10.0 Hz, 1H), 5.88 (s, 1H), 6.67 (d, J=10.0 Hz, 1H); 13C NMR (DMSO-d6): 10.17, 13.99, 23.54, 26.24, 27.23, 27.31, 37.99, 49.84, 76.35, 96.60, 102.88, 103.95, 107.80, 118.29, 123.55, 150.87, 153.82, 158.66, 160.26, 167.83; IR: 1683 cm−1; MS (ACPI+): 344 (M+1), 327 (M-NH3+1); Anal. Calcd. for C20H25NO4: C 69.95, H 7.34, N 4.08; Found C 69.97, H 7.30, N 4.08.

1. customSolvent and excess of ammonia were removed under vacuum
2. dissolutionthe residue re-dissolved in methanol (100 mL)
3. temperatureThe solution was cooled to 0° C.
4. temperatureto warm up room temperature
5. stirringstirred for 3 h
6. extractionThe product was extracted into ethyl acetate (3×50 mL)
7. washwashed with brine
8. dry with materialdried over anhydrous sodium sulfate
9. concentrationconcentrated under vacuum
10. customThe residue was chromatographed on silica gel column
11. washeluted with 5-10% methanol in dichloromethane