GENERAL METHOD: DL-Phenylalanine (8.16 g, 0.040 mol) was dissolved in methanol (80 mL) and thionyl chloride (SOCl2, 14.28 g, 0.120 mol) was added slowly and dropwise. The reaction mixture was stirred at room temperature for 30 min. Subsequently, the reaction solution was concentrated and the solid product was collected by filtration. The solid residue was washed with acetone and dried under infrared lamp to afford methyl 2-amino-3-phenylpropionate hydrochloride (compound 3a) as a white solid (8.07 g, 92.54% yield). Melting point: 220°C (decomposition), literature value: 221-222°C.
