[N:1]1[CH:6]=[CH:5][N:4]=[CH:3][C:2]=1[C:7]([NH2:9])=[O:8].[OH2:10].S(=O)(=O)(O)O.NOS(O)(=O)=O.[CH3:22]O>O.O.O.O.O.O.O.S([O-])([O-])(=O)=O.[Fe+2]>[OH:10][CH2:22][C:5]1[N:4]=[CH:3][C:2]([C:7]([NH2:9])=[O:8])=[N:1][CH:6]=1Pyrazinecarboxylic acid amide (0.492 g, 4 mmol) was suspended in methanol (8 ml), water (4 ml) and concentrated sulphuric acid (0.22 ml, 4 mmol), then iron (II) sulphate heptahydrate (0.334 g, 1.2 mmol) was added and the mixture degassed. To this was then added hydroxylamine-O-sulphonic acid (1.36 g, 12 mmol). After 6 h more sulphuric acid and iron (II) sulphate heptahydrate were added. After a further 1 h the mixture was adjusted to pH 7, evaporated, and the residue extracted with methanol. This solution was pre-absorbed onto silica then purified by chromatography, eluting with 0–10% ‘2 M ammonia in methanol’ in dichloromethane, to give the title compound as an off-white solid (0.102 g, 17%); NMR [(CD3)2SO] 4.72 (2H, d), 5.72 (1H, t), 7.79 (1H, br s), 8.22 (1H, br s), 8.73 (1H, d), and 9.09 (1H, d).
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