GENERAL STEPS: Dissolve sodium bicarbonate (605 g, 5.72 mol) in water (3 L) and cool to 0-5°C in an ice bath. D-serine (200 g, 1.90 mol) was added in 8-10 portions, 20-30 minutes apart. Subsequently, a toluene solution of 50% benzyl chloroformate (780 g, 2.29 mol) was added slowly and dropwise over a period of 1 h. The temperature was maintained at 0-5°C. The reaction mixture was stirred at 0-5 °C for 2 h, then brought to room temperature and continued stirring for 2 h. The reaction was carried out at room temperature. Ethyl acetate (400 mL) was added and the pH was adjusted with hydrochloric acid to 2.0. The product was extracted with ethyl acetate (2 x 800 mL). The organic phases were combined and concentrated under reduced pressure to about 640 mL to give a suspension. Cyclohexane (1200 mL) was added and slurried for 6 hours. The purified product was collected by filtration and dried under reduced pressure at 50 °C to afford (R)-2-(((benzyloxy)carbonyl)amino)-3-hydroxypropanoic acid (432.5 g, 95% yield) as a white solid with a melting point of 119-120 °C (literature value of 119 °C) and [α]D25 -5.08 (c 2.7, acetic acid).IR (ν, cm-1 ): 1689 (C=O) 1749 (C=O), 3319 (NH), 3338 (OH).UV (λmax, nm): 208.1H NMR (CD3OD, δ, ppm, J/Hz): 3.83-3.92 (2H, m, CH2), 4.30 (1H, t, J=8.8, NCH), 5.13 (2H, s, CH2), 7.29- 7.40 (5H, m, Ph-H).13C NMR (CD3OD, δ, ppm): 57.7, 63.1, 67.7, 128.9 (2C), 129.0, 129.5 (2C), 138.1, 158.6, 173.8.Mass Spectrometry (m/z, Irel%): 238 [M-H]- (100).
