反应详情

A solution of (3S,4R)-2-(3-benzyl-4-hydroxy-chroman-7-yl)-4-trifluoromethyl-benzoic acid 2,2-dimethyl-propyl ester (2.34 g, 4.69 mmol) in isopropyl alcohol (23 mL) was treated with 10% aqueous sodium hydroxide (2.3 mL, 6.4 mmol) and heated at reflux for 3 hours. The reaction mixture was cooled to ambient temperature, poured into water (34 mL), and extracted with hexanes (23 mL) and isopropyl ether (13 mL). The aqueous layer was separated and extracted with hexanes (23 mL) and isopropyl ether (13 mL), adjusted to pH 2 with 6N aqueous hydrochloric acid, and extracted with ethyl acetate (two times 40 mL). The combined ethyl acetate extracts were washed with brine (40 mL), dried over magnesium sulfate, filtered and concentrated to a white foam which was recrystallized from toluene/hexanes. The resulting solids were filtered and washed with hexanes, and the wet cake was stirred with hexanes (20 mL) for 1 hour. The mixture was filtered, and the resulting solids were dried under vacuum to provide 1.01 g (50% yield) of (3S,4R)-2-(3-benzyl-4-hydroxy-chroman-7-yl)-4-trifluoromethyl-benzoic acid as a white solid: 1H NMR (400 MHz, CDCl3) δ8.00 (d, J=8.1 Hz, 1H), 7.67 (d, J=8.1 Hz, 1H), 7.64 (s, 1H), 7.18-7.36 (m, 6H), 6.91 (dd, J=7.9, 1H), 6.86 (d, J=1.7 Hz, 1H), 4.53 (d, J=4.2 Hz, 1H), 4.24 (dd, J=11.2, 2.7 Hz, 1H), 3.97 (dd, J=11.0, 4.0 HZ, 1H), 2.76 (dd, J=13.9, 6.4 Hz, 1H), 2.53 (dd, J=13.7, 9.3 Hz, 1H), 2.24-2.26 (m, 1H).

1. temperatureheated
2. temperatureat reflux for 3 hours
3. extractionextracted with hexanes (23 mL) and isopropyl ether (13 mL)
4. customThe aqueous layer was separated
5. extractionextracted with hexanes (23 mL) and isopropyl ether (13 mL)
6. extractionextracted with ethyl acetate (two times 40 mL)
7. washThe combined ethyl acetate extracts were washed with brine (40 mL)
8. dry with materialdried over magnesium sulfate
9. filtrationfiltered
10. concentrationconcentrated to a white foam which
11. customwas recrystallized from toluene/hexanes
12. filtrationThe resulting solids were filtered
13. washwashed with hexanes
14. filtrationThe mixture was filtered
15. customthe resulting solids were dried under vacuum