To a 150 mL round bottom flask was added 28.5 g (0.21 mol) of p-methoxybenzaldehyde, 21.8 g (0.21 mol) of malonic acid and 32.3 g (0.42 mol) of ammonium acetate dissolved in 150 mL of ethanol. The reaction mixture was heated to 75-80°C and the reaction was stirred under reflux conditions for 8 hours. Upon completion of the reaction, the reaction mixture was cooled to room temperature and stirring was continued for 20 hours. Subsequently, a white solid was collected by filtration to afford 23.6 g of 3-amino-3-(4-methoxyphenyl)propionic acid (racemic mixture) in 82.3% yield (based on p-methoxybenzaldehyde). The product was a white powder and its physical properties were as follows: 1H-NMR (δ, ppm, D2O): 2.50 (dd, 1H, J = 17.1, 6.8 Hz), 2.65 (dd, 1H, J = 17.1, 7.8 Hz), 3.24 (s, 3H), 6.46 (s, 1H), 6.48 (s, 1H), 6.86 (s, 1H), 6.88 (s, 1H); 13C-NMR (δ, ppm, D2O): 37.1, 50.7, 55.1, 114.3, 126.9, 128.2, 159.1, 172.7; MS (EI) m/z: 195 (M+); MS (CI, i-C4H10) m/z: 196 (MH+).
