Hydrazine hydrate (1:1) → 2-Amino-5-methoxypyridine

55.6 g (corresponding to 0.239 mol) of 2-bromo-3-methoxy-6-nitropyridine was dissolved in 1700 mL of ethanol, and 37.3 g (50% wet) of 10% palladium-carbon was added thereto under argon stream. To the mixture, 283 mL of hydrazine monohydrate was then added dropwise. After the reaction mixture was heated under reflux for 70 minutes, the reaction solution was cooled down to room temperature. Then, after palladium-carbon was filtered off, the residue was washed with ethanol, and the washings were combined with the filtrate. The combined solution was concentrated under reduced pressure. Then, 1300 mL of water and 130 mL of conc. aqueous ammonia were added to the concentrate, and the resulting mixture was extracted eight times with chloroform. The combined chloroform layers were dried over anhydrous sodium sulfate and concentrated under reduced pressure. The resulting crude product was distilled under reduced pressure to obtain 26.2 g (corresponding to 0.211 mol) of 2-amino-5-methoxypyridine (FIG. 3, Step 3).

1. temperatureAfter the reaction mixture was heated
2. temperatureunder reflux for 70 minutes
3. filtrationThen, after palladium-carbon was filtered off
4. washthe residue was washed with ethanol
5. concentrationThe combined solution was concentrated under reduced pressure
6. additionThen, 1300 mL of water and 130 mL of conc. aqueous ammonia were added to the concentrate
7. extractionthe resulting mixture was extracted eight times with chloroform
8. dry with materialThe combined chloroform layers were dried over anhydrous sodium sulfate
9. concentrationconcentrated under reduced pressure
10. distillationThe resulting crude product was distilled under reduced pressure

ORD record

ord-af26533621804a58a2f8cb289cb710f8

Source dataset

uspto-grants-2013_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08399672B2