Dimethylformamide → 3-Bromo-5-methoxybenzaldehyde
反応式
Br[C:2]1[CH:7]=[C:6]([O:8][CH3:9])[CH:5]=[C:4]([Br:10])[CH:3]=1.[Li]CCCC.CN([CH:19]=[O:20])C>CCOCC>[Br:10][C:4]1[CH:3]=[C:2]([CH:7]=[C:6]([O:8][CH3:9])[CH:5]=1)[CH:19]=[O:20]参加物
5
反応条件
- 温度
- -78 °C
実験手順
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.