Boron tribromide → 4-Bromo-3-nitrophenol
反応式
[Br:1][C:2]1[CH:7]=[CH:6][C:5]([O:8]C)=[CH:4][C:3]=1[N+:10]([O-:12])=[O:11].B(Br)(Br)Br>ClCCl>[Br:1][C:2]1[CH:7]=[CH:6][C:5]([OH:8])=[CH:4][C:3]=1[N+:10]([O-:12])=[O:11]参加物
4
反応条件
- 温度
- -78 °C
実験手順
4-Bromo-3-nitroanisole (2.32g, 10 mmol) was dissolved in 25 mL dichloromethane and cooled in an acetone-dry ice bath at −78° C. under nitrogen. A solution of BBr3 (1.0M in dichloromethane) (25 mL, 25 mmol) was added dropwise. Gradually increased temperature to 20° C., stirred for 30 h. The reaction mixture was cooled to 0° C. and distilled water (30 mL) was added dropwise. The aqueous layer was extracted with ethyl acetate (30 mL×2) . The combined organic layer was washed successively with saturated NaHCO, solution (30 mL×2). The organic layer was dried over anhydrous sodium sulfate, filtered and evaporated in vacuo. The residue was chromatographed over 100 g of silica gel using 3:1 mixture respectively of hexanes and ethyl acetate to give the phenol in 70% yield; 1H NMR(CDCl3) δ6.92(1H, dd, J1=2.9, J2=8.8), 7.36(1H, d, J=2.9), 7.56(1H, d, J=8.8); 13C NMR(CDCl3) δ105.2 113.4, 116.4, 121.4, 136.3, 155.9; HRMS calcd for C6H4NO3Br: 216.9374, found: 216.9375.