反应详情

温度

45 °C

Sodium nitrite (1.73 g, 25.1 mmol) was added portionwise to concentrated sulfuric acid (20 mL) at 0° C. The mixture was stirred at 45° C. until homogeneous, cooled to 0° C., and charged with a solution of 5-[2-fluoro-4-(methylthio)phenyl]-2-pyrazinamine (4.37 g, 18.6 mmol) in concentrated sulfuric acid (55 mL) at 0° C. The reaction was allowed to warm to 25° C., stirred for 15 min, then at 45° C. for 1 h. The reaction was poured onto ice and the pH was adjusted to ˜4 with 10N NaOH. The resulting tan precipitate was filtered, washed with water, and air-dried to afford a tan solid. The solid was refluxed in EtOH (300 mL), hot-filtered, and the filtrate concentrated to afford 5-[2-fluoro-4-(methylthio)phenyl]-2-pyrazinol (and tautomers thereof) (3.16 g, 72% yield, purity=87%) as a tan solid. 1H NMR (400 MHz, DMSO-d6) δ8.14 (d, 1H, J=1.2 Hz), 7.72-7.86 (m, 2H), 7.24-7.15 (m, 2H), 2.52 (s LRMS (ESI), m/z 237 (M+H).

1. temperaturecooled to 0° C.
2. temperatureto warm to 25° C.
3. stirringstirred for 15 min
4. additionThe reaction was poured onto ice
5. filtrationThe resulting tan precipitate was filtered
6. washwashed with water
7. customair-dried
8. customto afford a tan solid
9. filtrationhot-filtered
10. concentrationthe filtrate concentrated