Phosphorus oxychloride → 5-Bromo-2-chloro-3-ethoxypyridine
반응식
[Br:1][C:2]1[CH:3]=[N+:4]([O-])[CH:5]=[C:6]([O:8][CH2:9][CH3:10])[CH:7]=1.O=P(Cl)(Cl)[Cl:14]>C(Cl)Cl>[Br:1][C:2]1[CH:7]=[C:6]([O:8][CH2:9][CH3:10])[C:5]([Cl:14])=[N:4][CH:3]=1참가 물질
4
반응 조건
- 온도
- 45 °C
실험 절차
To a solution of 3-bromo-5-ethoxypyridine-1-oxide (40 g, 183 mmol) in DCM (200 mL) at 0° C. was slowly added POCl3 (159 mL, 1701 mmol) over 30 min. Then the resulting solution was warmed to 45° C. and stirred for 15 h. The mixture was concentrated and adjusted pH=9-10 with 10% NaOH solution, extracted with DCM (300 mL×2), dried over Na2SO4, filtered, and concentrated to give the crude product which was purified by silica column chromatography (10% EA: 90% PE, 800 g silica column). All fractions found to contain product by TLC (EA: PE=1:5, Rf=0.6) were combined and concentrated to yield an oil of 5-bromo-2-chloro-3-ethoxypyridine (30 g, 60.9 mmol, 33% yield): 1H NMR (400 MHz, CD3OD) δ 8.00-7.99 (d, J=2.0 Hz, 1H), 7.65-7.64 (d, J=2.0 Hz, 1H), 4.17-4.12 (m, 2H), 1.44 (t, J=7.0 Hz, 2H); ES-LCMS m/z 235 (M+H).