Yield:917918-86-6 81%

Reaction Conditions:

with sulfuric acid;nitric acid at 0 - 50; for 1 h;

Steps:

22 Example 227-fluoro-8methyl-5-azaquinoxaline-2,3-dione (22)

2-Amino-4-methyl-5-fluoropyridine (1 g, 7.93 mmol) at 0 ° C with stirringAdd in portions to 15 ml of concentrated sulfuric acid,When the solid was completely dissolved, fuming nitric acid (0.43 mL, 10.3 mmol) was slowly added dropwise.Slowly rise to 50 ° C and continue to stir for 1 hour.Pour the reaction solution into 100 g of ice water and adjust the pH to 9-10 with concentrated ammonia water.The resulting yellow solid was filtered.The yellow solid was recrystallized (petroleum ether / ethyl acetate = 5:1) to give 2-amino-3-nitro-4-methyl-5-fluoropyridine.(1.1 g, yield 81%).

References:

CN103435561,2016,B Location in patent:Paragraph 0341; 0342