反应详情

温度

-20 °C

3-(N-Cyclopropylamino)-5-metoxychroman hydrochloride (5.6 g, 22 mmol) was suspended in CH2Cl2 (140 mL) under N2. The mixture was cooled on a dry-ice/EtOH bath to -20° C. BBr3 (4.1 mL, 44 mmol) dissolved in CH2Cl2 (60 mL) was added to the stirred mixture during 0.5 hour. The yellow clear solution was slowly warmed to 0° C. and kept at that temperature until GC indicated a complete reaction (after 3-5 hours). Then the solution was poured on crushed ice (200 g) and enough conc. NH3 (aq.) to make a pH of 8-9. The mixture was extracted with ether (3×200 mL). The collected ether phases were dried (MgSO4), filtered and concentrated in vacuo to afford a white solid. Crystallization from absolute EtOH afforded 3-(N-cyclopropylamino)-5-hydroxychroman (3.9 g, 88% yield) as colourless needles. Mp 147°-148° C.

1. additionwas added to the stirred mixture during 0.5 hour
2. temperatureThe yellow clear solution was slowly warmed to 0° C.
3. customa complete reaction (after 3-5 hours)
4. additionThen the solution was poured
5. extractionThe mixture was extracted with ether (3×200 mL)
6. dry with materialThe collected ether phases were dried (MgSO4)
7. filtrationfiltered
8. concentrationconcentrated in vacuo
9. customto afford a white solid
10. customCrystallization from absolute EtOH