[Synthesis]
(1) Synthesis of diethyl anilino malonate: Aniline (18.6 g, 0.20 mol) was dissolved in anhydrous benzene (125 mL), followed by the addition of diethyl bromomalonate (23.9 g, 0.10 mol). The reaction mixture was heated to reflux under continuous stirring and maintained for 37 hours. Upon completion of the reaction, the reaction mixture was washed with dilute hydrochloric acid to remove unreacted aniline. The organic layer was separated, washed three times with water and dried with anhydrous magnesium sulfate. Subsequently, the solvent was removed by distillation under reduced pressure. The crude product was purified by silica gel column chromatography using hexane/ethyl acetate (10:1, v/v) as eluent to afford 7.5 g (30% yield) of diethyl anilino malonate. The product was characterized by nuclear magnetic resonance (NMR) with the following data: 1H NMR (δ, TMS, CCl4): 1.20 (6H, t, J = 7 Hz), 4.20 (4H, q, J = 7 Hz), 4.66 (2H, s, br; changed to 1H after addition of D2O), 6.5-7.3 (5H, m). |