General procedure for the synthesis of ethyl 5-nitropyridinecarboxylate from 5-nitro-2-pyridinecarboxylic acid and ethanol: 5-nitro-2-pyridinecarboxylic acid (38.0 g, 226 mmol) was dissolved in thionyl chloride (50.0 mL, 686 mmol), and heated to reflux for 1 hour. Upon completion of the reaction, the mixture was concentrated to dryness to give a solid. The solid was dissolved in anhydrous ethanol (100 mL) and the reaction was refluxed for 2 hours and then cooled to room temperature. Subsequently, the solvent was removed by evaporation under reduced pressure. The resulting solid residue was dissolved in ethyl acetate (500 mL) and washed sequentially with 1 M aqueous sodium bicarbonate (2 x 300 mL). The organic phase was dried over anhydrous sodium sulfate and concentrated to give 39.0 g (86% yield) of yellow solid product with >95% purity (confirmed by 1H NMR and LC-MS analysis).1H NMR (DMSO-d6) δ: 9.46 (d, 1H, J = 2.1 Hz), 8.76 (dd, 1H, J = 2.1, 8.8 Hz), 8.29 (d, 1H, J = 8.6), 8.29 (d, 1H, J = 8.6). 1H, J = 8.6 Hz), 4.41 (q, 2H, J = 7.1 Hz), 1.36 (t, 3H, J = 7.1 Hz).LC-MS (APCI) m/z: [M + H]+ 197.
