反应详情

Under ice cooling, to 5-fluoropyridine-2-amine (10.36 g) was added concentrated sulfuric acid (48 ml), followed by stirring for 10 minutes, and then fuming nitric acid (3.83 ml) was added dropwise over 30 minutes. Stirring was carried out at room temperature for 1 hour, and further at 55° C. for 90 minutes. Ice was poured thereinto, and neutralized with a 10 N aqueous sodium hydroxide solution, followed by concentration under reduced pressure. The residue was dissolved in dichloromethane (600 ml), followed by stirring for 30 minutes, and then the insolubles were filtered off to concentrate the filtrate under reduced pressure. The residue was purified by silica gel column chromatography to afford 5-fluoro-3-nitropyridine-2-amine (2.66 g).

1. stirringStirring
2. waitwas carried out at room temperature for 1 hour
3. waitfurther at 55° C. for 90 minutes
4. additionIce was poured
5. concentrationfollowed by concentration under reduced pressure
6. dissolutionThe residue was dissolved in dichloromethane (600 ml)
7. stirringby stirring for 30 minutes
8. filtrationthe insolubles were filtered off
9. concentrationto concentrate the filtrate under reduced pressure
10. customThe residue was purified by silica gel column chromatography