反应详情

温度

45 °C

Sodium nitrite (77 mg, 1.109 mmol) was added portionwise to concentrated sulfuric acid (2 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-methyl-4-(methylthio)phenyl]-2-pyrazinamine (190 mg, 0.821 mmol) in sulfuric acid (3 mL) at 0° C. The mixture was warmed to ambient temperature, stirred at ambient temperature for 15 min, then at 45° C. for 5 h. The mixture was cooled to ambient temperature, poured into water, and the pH was adjusted to ˜4 with 10N NaOH. The resulting precipitate was filtered, washed with water, and air-dried to give 100 mg (52%) of 5-[2-methyl-4-(methylthio)phenyl]-2-pyrazinol (and tautomers thereof) as a tan solid. 1H NMR (400 MHz, DMSO-d6): δ 12.61-12.37 (m, 1H), 8.08 (d, 1H, J=1.0 Hz), 7.72-7.45 (m, 1H), 7.30 (d, 1H, J=8.1 Hz), 7.22-7.06 (m, 2H), 2.48 (s, 3H), 2.30 (s, 3H); LRMS (ESI), m/z 233 (M+H).

1. temperaturecooled to 0° C.
2. temperatureThe mixture was warmed to ambient temperature
3. stirringstirred at ambient temperature for 15 min
4. temperatureThe mixture was cooled to ambient temperature
5. filtrationThe resulting precipitate was filtered
6. washwashed with water
7. customair-dried