[Cl:1][C:2]1[CH:7]=[CH:6][CH:5]=[C:4]([CH3:8])[N+:3]=1[O-:9].[N+:10]([O-])([OH:12])=[O:11].C([O-])(O)=O.[Na+]>S(=O)(=O)(O)O>[Cl:1][C:2]1[CH:7]=[C:6]([N+:10]([O-:12])=[O:11])[CH:5]=[C:4]([CH3:8])[N+:3]=1[O-:9]2-chloro-6-methylpyridine 1-oxide (60 g, 0.42 mol) was dissolved in 98% sulfuric acid (60 mL) at 0° C., then a solution of HNO3 (50 mL) and H2SO4 (50 mL) was added dropwise at the same temperature. After the addition was complete, the reaction was stirred at 90° C. for 3 h. The reaction was poured into ice-water, neutralized with NaHCO3, and then extracted with ethyl acetate (3×500 mL). The combined organic layers were washed with brine (500 mL), dried over magnesium sulfate, filtered and concentrated to afford 2-chloro-6-methyl-4-nitropyridine 1-oxide which was used without further purification. 1H NMR (300 MHz, CDCl3) δ 8.27 (d, J=2.7 Hz, 1H), 8.07 (d, J=0.6 Hz, 1H), 2.62 (s, 3H). LRMS calc'd for (C6H6ClNO) [M+H]+, 189; found 189.
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