反应详情

4-Chloro-5-fluoro-2-picoline-N-oxide (12.43 g, 76.93 mmol), from Step 7, was dissolved in 52 mL of glacial acetic acid in a 3-necked flask equipped with a mechanical stirrer, a condenser and a thermometer. Iron powder (6.45 g, 115.5 mmol) was added to the solution at ambient temperature and the reaction mixture was carefully heated to 35°-40° C. After 10 min at 30° C., an exothermic reaction took place which caused the reaction temperature to rise to 120° C. and the reaction mixture became a very dark brown-colored solution. The flask was transferred to a cold water bath and the temperature of the solution brought down to ambient. The reaction mixture was then poured over ice. The resultant aqueous mixture was adjusted to pH 9 with potassium carbonate and steam distilled. The aqueous distillate collected at 92°-96° C. was extracted with three portions of methylene chloride. The combined organic extract was dried over anhydrous sodium sulfate, filtered and distilled to afford 15.91 g (71% yield) of the title compound, b.p. 138°-140° C.; MS GC-MS M/Z:146 (M+H)+ ; 1H NMR (CDCl3) d 2.53 (s, 3H), 7.23 (d, 1H, J=6.0 Hz), 8.37 (s, 1H).

1. customequipped with a mechanical stirrer, a condenser
2. temperaturethe reaction mixture was carefully heated to 35°-40° C
3. customan exothermic reaction
4. customto rise to 120° C.
5. customThe flask was transferred to a cold water bath
6. additionThe reaction mixture was then poured over ice
7. distillationdistilled
8. distillationThe aqueous distillate collected at 92°-96° C.
9. extractionwas extracted with three portions of methylene chloride
10. extractionThe combined organic extract
11. dry with materialwas dried over anhydrous sodium sulfate
12. filtrationfiltered
13. distillationdistilled