反应详情

To 85 ml of concentrated sulfuric acid was added 7.0 g of 3-(2,4-difluorophenyl)-1-methyl-6-trifluoromethyl-2-oxo-1,2-dihydropyrazine (present compound 1-10) at 5° C. Furthermore, 9 ml of 70% nitric acid was added, and the mixture was stirred at 5° to 10° C. for 8 hours. After completion of the reaction, the reaction mixture was added to ice water, followed by extraction with ethyl acetate. The organic layer was washed with water and then saturated sodium chloride solution, dried with anhydrous magnesium sulfate, and concentrated. The residue was subjected to silica gel column chromatography, which afforded 7.76 g (yield, 96%) of 3-(2,4-difluoro-5-nitrophenyl)-1-methyl-6-trifluoromethyl-2-oxo-1,2-dihydropyrazine (present compound 1-16; m.p., 93.2° C.).

1. customAfter completion of the reaction
2. extractionfollowed by extraction with ethyl acetate
3. washThe organic layer was washed with water
4. dry with materialsaturated sodium chloride solution, dried with anhydrous magnesium sulfate
5. concentrationconcentrated