Under argon protection, N-chlorosuccinimide (0.53 g, 3.95 mmol) was slowly added to a solution of 2-amino-5-nitropyridine (0.50 g, 3.59 mmol) in anhydrous toluene (7.18 mL). The reaction mixture was stirred continuously at 80 °C for 1 hour. After completion of the reaction, the mixture was cooled to room temperature and diluted with 15 mL of water. Subsequently, extraction was carried out with ethyl acetate and the organic layer was washed sequentially with saturated sodium bicarbonate solution and brine. The organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and the resulting crude product was purified by column chromatography (silica gel 60N, gradient elution of n-hexane/ethyl acetate = 80/20 to 60/40) to afford 2-amino-3-chloro-5-nitropyridine (0.40 g, 2.30 mmol, 64% yield) as a yellow solid. The structure of the product was analyzed by nuclear magnetic resonance hydrogen spectrum (1H NMR, 500 MHz, DMSO-d6) δ 8.84 (d, J = 2.5 Hz, 1H), 8.35 (d, J = 2.5 Hz, 1H), 7.91 (brs, 1H); nuclear magnetic resonance carbon spectrum (13C NMR, 125 MHz, DMSO-d6) δ 112.58, 132.14, 135.01, 145.25, 159.75; high-resolution mass spectrometry (HRMS, ESI-TOF, m/z) calculated values of C5H4ClN3O2Na [M + Na]+: 195.9884, 197.9856, measured values: 195.9878, 197.9847 confirmed.
