The general procedure for the synthesis of 2-cyano-3-methyl-5-nitropyridine from 2-cyano-3-methylpyridine was as follows: 3-methylpyridine-2-carbonitrile (128 g, 1.08 mol) and tetrabutylammonium nitrate (363 g, 1.19 mol) were dissolved in tertiary-butylmethyl ether (1.3 L) and the mixture was cooled down to 4 °C. Trifluoroacetic anhydride (171 mL, 1.21 mol) was slowly added under stirring, followed by continuous stirring of the reaction mixture for 60 hours at room temperature. Upon completion of the reaction, the pH of the mixture was adjusted to about 7 with 20% aqueous sodium hydroxide solution and then extracted with dichloromethane (3 x 1 L). The organic layers were combined, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure. Purification of the crude product by silica gel column chromatography (elution gradient: 0% to 10% petroleum ether solution of ethyl acetate) afforded the target compound 2-cyano-3-methyl-5-nitropyridine as a yellow solid. Yield: 70 g, 0.43 mmol, 40% yield.1H NMR (400 MHz, CDCl3) δ 9.31-9.36 (m, 1H), 8.47-8.52 (m, 1H), 2.74 (s, 3H).
