15399-22-1

67-56-1

1492-24-6

2483-62-7

Step 1: Preparation of methyl (2S)-2-aminobutyrate; (2S)-2-aminobutyric acid (21.56 g, 0.21 mol) was dissolved in 120 mL of methanol. The reaction mixture was cooled to 0°C in an ice-water bath and thionyl chloride (30.5 mL, 0.42 mol) was added slowly and dropwise with continuous stirring. After the dropwise addition, the reaction mixture was heated to reflux for 2 hours and subsequently cooled to room temperature. The solvent was removed by concentration under reduced pressure to afford methyl (2S)-2-aminobutyrate (31.87 g, 99.3% yield) as a white solid.