[N+:1]([O-:4])(O)=[O:2].[Br:5][C:6]1[CH:11]=[CH:10][CH:9]=[C:8]([CH3:12])[N+:7]=1[O-:13]>S(=O)(=O)(O)O>[Br:5][C:6]1[CH:11]=[C:10]([N+:1]([O-:4])=[O:2])[CH:9]=[C:8]([CH3:12])[N+:7]=1[O-:13]To cooled nitric acid (concentrated, 168 ml) was added sulfuric acid (concentrated, 300 ml) under cooling followed by 2-bromo-6-methyl-pyridine 1-oxide (35 g, 0.186 mol). The mixture was stirred at 70° C. for 4 hours, cooled to room temperature and poured slowly on crushed ice. A stream of nitrogen was bubbled through the mixture overnight. The mixture was basified to pH 8 under cooling with NaOH (10N, ca. 1 L), diluted with water (3 L) and extracted with DCM (5×). The combined organic phases were dried (sodium sulfate) and evaporated to dryness to yield 27.6 g of a yellow crystalline solid (0.118 mol, 57%).
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