反应详情

Sodium nitrite (4.5 g, 66 mmol) was added slowly to a solution of 6-amino-3-bromo-2-methylpyridine (3.07 g, 16.4 mmol) in concentrated HCl (40 mL) at −20° C. After 1 h, the reaction was allowed to warm to room temperature and stirred overnight. The reaction was carefully neutralized with ice-cold 5N NaOH until pH=11. The aqueous layer was extracted with Et2O (3×75 mL). The combined organic layers were washed with brine (1×75 mL), dried (Na2SO4) and concentrated in vacuo to afford 3-bromo-6-chloro-2-methylpyridine, as a white solid, which was used in the next step without further purification. LCMS calc.=205.9; found=206.0 (M+1)+. 1H NMR (500 MHz, CDCl3) δ 7.76 (d, J=8.2 Hz, 1H); 7.07 (d, J=8.1 Hz, 1H); 2.66 (s, 3H).

1. extractionThe aqueous layer was extracted with Et2O (3×75 mL)
2. washThe combined organic layers were washed with brine (1×75 mL)
3. dry with materialdried (Na2SO4)
4. concentrationconcentrated in vacuo