3-Aminopropionic acid (1.0 g, 11 mmol) was dissolved in tetrahydrofuran (10 mL) and 10% sodium hydroxide aqueous solution (11 mL). The solution was cooled to 5 °C, and di-tert-butyl dicarbonate (2.9 mL, 12 mmol) was added dropwise. The mixture was stirred at room temperature for 12 hours. Water (40 mL) was added, and the mixture was extracted with ethyl acetate (20 mL × 2). The aqueous phase was adjusted to pH 2 with 4 mol/L hydrochloric acid and then extracted with ethyl acetate (30 mL × 3). The extract was dried over anhydrous sodium sulfate. The mixture was filtered and concentrated under reduced pressure to give the title compound, Boc-beta-alanine, as a white solid (1.7 g, 80% yield).
