反应详情

To a solution of 0,45 g (1,9 mmol) 2,3-dihydroxy-8,9-dimethylpyrazino(2,3-f)quinoxaline in 30 ml concentrated sulfuric acid was added at 0° C. 384 mg (3,8 mmol) potassium nitrate. Stirring was continued at 0° C. for 30 min. and at 25° C. for 24 h. The reaction mixture was poured into 150 ml ice-water. The solution was added 10N sodium hydroxide to pH 7, and then extracted with ethyl acetate (5×100 ml). The combined and dried ethyl acetate phases were evaporated to give 0,18 g (33%) 2,3-dihydroxy-8,9-dimethyl-6-nitropyrazino(2,3-f)quinoxaline, m.p.>300° C. NMR (DMSO-d6) 8.07 (1H,s), 2.77 (3H,s), 2.73 (3H,s).

1. extractionextracted with ethyl acetate (5×100 ml)
2. customdried ethyl acetate phases were evaporated