反应详情

A mixture containing (2S)-3-(4-hydroxy-phenyl)-2-methoxy-propionic acid ethyl ester obtained in Step 1 (0.223 mol, 50 mg), potassium carbonate (0.446 mol, 50 mg), magnesium sulfate (powdered, 50 mg, 1 g/g), ethylene dibromide (3.35 mol. 628 mg) and EtOH (25 mL) was heated at reflux (78–76° C.) for 24 hours and cool to room temperature. The mixture was heated again to reflux (76.5–77° C.) and 2 mL of ethylene dibromide was added. The mixture was heated for another 12 hours at 79.5–80.1° C. and then cooled to room temperature and vacuum filtered. The filtrate was concentrated under vacuum, and the residue was purified by column chromatography (silica gel, hexanes/ethyl acetate 6:1, Rf 027) to produce a colorless oil. MS (ES) for C14H19BrO4 [M+Na]+: 353.0.

1. temperaturewas heated
2. temperatureat reflux (78–76° C.) for 24 hours
3. temperatureThe mixture was heated again
4. additionwas added
5. temperatureThe mixture was heated for another 12 hours at 79.5–80.1° C.
6. temperaturecooled to room temperature
7. filtrationvacuum filtered
8. concentrationThe filtrate was concentrated under vacuum
9. customthe residue was purified by column chromatography (silica gel, hexanes/ethyl acetate 6:1, Rf 027)
10. customto produce a colorless oil