Synthesis
2-Methoxy-6-methylpyridine (1.95 g, 15 mmol) was used as starting material and 60% nitric acid (7 mL) was added. The reaction mixture gradually changed to reddish brown color, accompanied by exothermic phenomenon and generation of nitrogen dioxide gas. Subsequently, concentrated sulfuric acid (7 mL) was added slowly. The reaction system was stirred at 80°C overnight. Upon completion of the reaction, the cooled reaction mixture was slowly poured into ice water (70 mL) and neutralized with calcium carbonate. The aqueous phase was extracted with ethyl acetate (3 x 50 mL), the organic phases were combined and dried over anhydrous sodium sulfate. The desiccant was removed by filtration and the organic phase was concentrated to dryness under reduced pressure to give 6-methoxy-2-methyl-3-nitropyridine (2.25 g, 86% yield) as a yellow solid. Nuclear magnetic resonance hydrogen spectroscopy (1H NMR, DMSO-d6) data were as follows: δ 8.3 (d, 1H), 6.8 (d, 1H), 4.0 (s, 3H), 2.7 (s, 3H).
