Compound 18 was synthesized by mixing p-nitroaniline (0.34 g, 0.0024 mol), 2-chloro-8-methylquinoline-3-carbaldehyde (0.5 g, 0.0024 mol), potassium carbonate (0.67 g, 0.0047 mol), and moist copper powder (0.1 g, 0.0016) in a 100 mL round-bottom flask containing N,N-dimethylformamide (20 mL). A water condenser was fitted into the neck, and the mixture was refluxed for 5 hours; meanwhile, the progress of the reaction was attended by TLC. After being cooled to room temperature, it was added to 100 mL crushed ice water. The solid product was separated by suction filtration and washed with 5% HCl solution (50 mL) and allowed to dry in air. The product was a gray powder, and the yield was 0.93 g (85.3%)
An aqueous solution of KOH (1 mL, 40%) was added dropwise to a mixture of 8-methyl-2-((4-nitrophenyl)amino)quinoline-3-carbaldehyde (0.68 g, 2.2 mmol) and benzyltriphenylphosphonium chloride (0.86 g, 2.2 mmol) dissolved in DMF (15 mL) in a 100 mL round-bottom flask while being stirred with a magnetic stirrer. The stirring was continued overnight until TLC analysis showed the complete conversion of the reactant. Then, the mixture was poured to 150 mL crushed ice water, and the precipitate was separated by suction filtration and washed with 30 mL cold water. The product was a pink powder, and the crude yield was 1.07 g (92%)
