To 5.00 g (40.3 mmol) of 3-fluorobenzaldehyde was added 20 mL of ethanol followed by 4.19 g (40.3 mmol) of malonic acid and 4.66 g (60.4 mmol) of ammonium acetate. The mixture was heated to 80 to 90°C with stirring and the reaction was refluxed for 7 hours. Upon completion of the reaction, the reaction mixture was cooled to 0 to 5°C and stirring was continued for 1 h. Subsequent filtration afforded 4.27 g of 3-amino-3-(3-fluorophenyl)propionic acid (racemic mixture) as a white powder (57.9% isolated yield based on 3-fluorobenzaldehyde).
The physical properties of 3-amino-3-(3-fluorophenyl)propionic acid (racemic mixture) were as follows:
1H-NMR (δ (ppm), D2O): 2.83 (dd, 1H, J = 16.1, 6.8 Hz), 2.90 (dd, 1H, J = 16.1, 7.8 Hz), 4.67 (dd, 1H, J = 6.8, 7.8 Hz), 7.2-7.5 (m, 5H).
13C-NMR (δ (ppm), D2O): 43.4, 55.1, 116.9, 119.0, 125.7, 134.0, 141.5, 164.3, 179.9.
MS (EI) m/z: 183 (M+).
MS (CI, i-C4H10) m/z: 184 (MH+).
