The general procedure for the synthesis of D-homoserine from D-methionine was as follows: D-methionine (1) (25.0 g, 167.5 mmol, 1 eq.) was suspended in a mixed H2O/MeOH solvent (466 mL/66 mL) according to the literature method, followed by the addition of methyl iodide (25.2 mL, 405.4 mmol, 2.4 eq.). The resulting suspension was stirred vigorously at room temperature for 48 hours. Upon completion of the reaction, the volume of the reaction mixture was concentrated to one-third of the original volume by vacuum evaporation, while the excess methyl iodide was removed. To the remaining reaction mixture was added water (155 mL) followed by NaHCO3 (14.07 g, 167.5 mmol, 1 equiv). The resulting solution was refluxed for 15 hours and then cooled to room temperature. The solvent was removed under vacuum to give a thick syrupy substance. The syrupy substance was dissolved in water (45 mL) under heating, followed by sequential addition of acetone (90 mL) and ethanol (1000 mL), and a white solid precipitate was observed. The precipitate was filtered and dried under vacuum to give a white solid of the target product D-homoserine (2). Yield: 9.9 g (83 mmol, 50% yield). Melting point: 202°C. 1H NMR (300 MHz, D2O): δ = 1.92-1.78 (m, 1H, 3-CH), 2.09-2.92 (m, 1H, 3-CH), 3.65-3.58 (m, 2H, 4-CH2), 3.68 (dd, 3JH,H = 4.8, 3JH,H = 7.5 Hz, 1H, 2-CH ).13C NMR (75 MHz, D2O): δ = 32.1 (s, 3-C), 53.3 (s, 2-C), 58.5 (s, 4-C), 174.5 (s, 1-C).HRMS (ESI+, MeOH): m/z = 142.0468 [M + Na]+ with a calculated value of 142.0475 for C4H9NO3Na.
