反应详情

To a cooled (0° C.) solution of 5-bromo-2-chloro-3-nitropyridine (50 g, 211 mmol) in methanol (200 mL) was added dropwise over 10 minutes 20% sodium methoxide (50 mL, 211 mmol) solution. The reaction, which quickly became heterogeneous, was allowed to warm to ambient temperature and stirred for 16 h. The reaction was filtered and the precipitate diluted with water (200 mL) and stirred for 1 h. The solids were filtered, washed with water (3×100 mL) and dried in a vac oven (40° C.) to give 5-bromo-2-(methyloxy)-3-nitropyridine (36 g, 154 mmol, 73.4% yield) as a pale yellow powder. The original filtrate was concentrated in vacuo and diluted with water (150 mL). Saturated ammonium chloride (25 mL) was added and the mixture stirred for 1 h. The solids were filtered, washed with water, and dried in a vac oven (40° C.) to give a second crop of 5-bromo-2-(methyloxy)-3-nitropyridine (9 g, 38.6 mmol, 18.34% yield). Total yield=90%. MS (ES)+m/e 232.8, 234.7 [M+H]+.

1. customThe reaction, which quickly became heterogeneous
2. filtrationThe reaction was filtered
3. additionthe precipitate diluted with water (200 mL)
4. stirringstirred for 1 h
5. filtrationThe solids were filtered
6. washwashed with water (3×100 mL)
7. customdried in a vac oven (40° C.)