反应详情

2,3-Dimethyl-pyrazine 1-oxide (25 g, 0.2 mol) was dissolved in POCl3 (200 mL) under cooling. The mixture was gradually heated to reflux and stirred for 2 hours. After cooling, the reaction mixture was poured onto ice, basified to pH 8 with a saturated KOH solution under cooling and extracted with EtOAc. The combined organics were dried over Na2SO4 and concentrated. The residue was purified by column (P.E./EtOAc 100:1-60:1) to obtain 5-chloro-2,3-dimethylpyrazine. 1HNMR (CDCI3, 300 MHz) δ 8.31 (s, 1H), 2.53 (s, 6H). MS (ESI) m/e (M+H+) 143.2.

1. temperatureunder cooling
2. temperatureThe mixture was gradually heated
3. temperatureto reflux
4. temperatureAfter cooling
5. additionthe reaction mixture was poured onto ice
6. temperatureunder cooling
7. extractionextracted with EtOAc
8. dry with materialThe combined organics were dried over Na2SO4
9. concentrationconcentrated
10. customThe residue was purified by column (P.E./EtOAc 100:1-60:1)