反应详情

To a solution of 0,38 g (1,4 mmol) 2,3-dihydroxy-pyrazino(2,3-f)quinoxaline in 25 ml concentrated sulfuric acid was added at 0° C. 0,28 g (2,8 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 100 ml ice-water. The solution was added 10 N 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 0,17 g (47%) 2,3-dihydroxy-6-nitropyrazino(2,3-f)quinoxaline, m.p. >300° C. NMR (DMSO-d6) 9.10 (2H,s), 8.23 (1H,s).

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