Preparative Example 1 Synthesis of 1-(2-chloro-4-nitrophenyl)-4-methylpiperazine: in a dry reaction flask, 3-chloro-4-fluoronitrobenzene (10.05 g, 57.2 mmol) was mixed with N-methylpiperazine (17.2 g, 172 mmol). Exothermic phenomenon was observed during the reaction and after 1 h of continuous stirring, the reaction mixture was quenched by adding water to the reaction mixture. The resulting brown solid precipitate was collected by filtration and washed with plenty of water to remove unreacted raw materials and by-products. Finally, the product was dried in air to afford 1-(2-chloro-4-nitrophenyl)-4-methylpiperazine (14.1 g, 96% yield). The product was confirmed by 1H NMR (400 MHz, DMSO-d6) and mass spectrometry (MS) characterization: 1H NMR δ 2.24 (s, 3H), 2.43-2.55 (m, 4H), 3.11-3.24 (m, 4H), 7.28 (d, J = 9.03 Hz, 1H), 8.14 (dd, J = 9.03,2.76 Hz, 1H) , 8.21 (d, J = 2.51Hz, 1H); MS m/z 255 (M+).
