To a 150 mL round bottom flask was added 30.5 g (0.25 mol) of 4-fluorobenzaldehyde, 25.6 g (0.25 mol) of malonic acid and 28.4 g (0.37 mol) of ammonium acetate dissolved in ethanol. The reaction mixture was heated to 75-80°C and the reaction was stirred under reflux conditions for 8 hours. After completion of the reaction, the mixture was cooled to room temperature and stirring was continued for 1 hour. Subsequently, the precipitate was collected by filtration and dried under reduced pressure at 45°C to give 28.3 g of 3-amino-3-(4-fluorophenyl)propionic acid (racemic mixture) in 62.8% yield (calculated based on 4-fluorobenzaldehyde), the product was a white powder.
The physical properties of 3-amino-3-(4-fluorophenyl)propionic acid (racemic mixture) were as follows:
1H-NMR (δ, ppm, D2O): 2.49 (dd, 1H, J = 17.1, 6.8 Hz), 2.62 (dd, 1H, J = 17.1, 7.8 Hz), 4.20 (dd, 1H, J = 7.8, 6.8 Hz), 6.58-6.62 (m, 2H), 6.88-6.91 (m, 1H)
13C-NMR (δ, ppm, D2O): 37.1, 50.5, 115.5, 115.8, 128.9, 130.4, 172.6
MS (EI) m/z: 183 (M+)
MS (CI, i-C4H10) m/z: 184 (MH+)
