反应详情

温度

-78 °C

step 2—To a solution of 1,3-dibromo-5-methoxy-benzene (60 g, 0.2256 mol) and anhydrous Et2O (1 L) cooled to −78° C. and maintained under an Ar atmosphere was added dropwise over 30 min n-BuLi (100 mL, 0.2482 mol, 2.5M in hexane). The yellow solution was stirred at −78° C. for 20 min. To the reaction mixture was added dropwise dry DMF (19 mL, 248.2 mmol) over 15 min and the reaction stirred at −78° C. for 10 min before the cooling bath was removed and the reaction allowed to warm to −30° C. over 30 min. The reaction vessel was placed in an ice-water bath and warmed to −10° C. The mixture was slowly added to an ice cold saturated aqueous NH4Cl solution (400 mL). The organic layer was separated and the aqueous phase thrice extracted with Et2O. The combined extracts were washed with water, dried (MgSO4), filtered and evaporated to afford an oil which solidified on standing. The crude product was purified by SiO2 chromatography eluting with a hexane/EtOAc gradient (3 to 5% EtOAc) to afford 3-bromo-5-methoxy-benzaldehyde.

1. temperaturemaintained under an Ar atmosphere
2. stirringthe reaction stirred at −78° C. for 10 min before the cooling bath
3. customwas removed
4. temperatureto warm to −30° C. over 30 min
5. customThe reaction vessel was placed in an ice-water bath
6. temperaturewarmed to −10° C
7. additionThe mixture was slowly added to an ice cold saturated aqueous NH4Cl solution (400 mL)
8. customThe organic layer was separated
9. extractionthe aqueous phase thrice extracted with Et2O
10. washThe combined extracts were washed with water
11. dry with materialdried (MgSO4)
12. filtrationfiltered
13. customevaporated
14. customto afford an oil which
15. customThe crude product was purified by SiO2 chromatography
16. washeluting with a hexane/EtOAc gradient (3 to 5% EtOAc)