反应详情

温度

2.5 °C

To a solution of racemic-trans-3,6-dibromochroman-4-ol (30.0 g, 97.4 mmol) in isopropyl alcohol (300 mL) at ambient temperature (500 mL), add ammonium hydroxide (28-30% aq., 150 mL, 2.2 mol). Stir slowly for 15 hr. Filter the reaction mixture and dilute the filtrate with water (200 mL). Concentrate the resulting solution under reduced pressure to one half of its original weight. Add water (100 mL), stir the mixture at ambient temperature for 10 min., then cool to 0-5° C. and stir for an additional 30 min. Collect the precipitate by filtration and wash the solids with water (25 mL) and heptanes (25 mL). Vacuum dry the material at 40° C. to afford the title compound as a pale yellow solid (21.2 g, 89.2%). 1H NMR (DMSO-d6) δ 1.96 (bs, 2H), 3.53 (m, 2H), 3.87 (dd, 1H), 4.11 (dd, 1H), 5.15 (bs, 1H), 6.66 (d, 1H), 7.19 (dd, 1H), 7.48 (dd, 1H). LC-ES/MS m/z (79Br) 244 [M+H].

1. filtrationFilter the reaction mixture
2. additiondilute the filtrate with water (200 mL)
3. concentrationConcentrate the resulting solution under reduced pressure to one half of its original weight
4. stirringAdd water (100 mL), stir the mixture at ambient temperature for 10 min.
5. stirringstir for an additional 30 min
6. customCollect the precipitate
7. filtrationby filtration
8. washwash the solids with water (25 mL) and heptanes (25 mL)
9. customVacuum dry the material at 40° C.