(S)-(-)-2-Amino-4-pentenoic acid (2.0 g) was suspended in dioxane (80 mL) at room temperature and triethylamine (4.3 g), water (2.0 mL) and N-(phenylmethoxycarbonyloxy)succinimide (9.1 g) were added sequentially. The reaction mixture was stirred overnight at room temperature and then concentrated under vacuum. Subsequently, the reaction mixture was diluted with saturated NaHCO3 solution and extracted with ether (3 x 80 mL). The basic aqueous layer was acidified to pH 2 with 2N HCl and extracted with EtOAc (3 x 80 mL). The EtOAc layers were combined, washed with brine, dried over anhydrous Na2SO4, filtered and the solvent evaporated. Finally, a viscous oily product (4.41 g, quantitative yield) was obtained by concentration from toluene (2 × 20 mL). The product was confirmed by 1H NMR (300 MHz, DMSO-d6): δ 2.31-2.50 (m, 2H), 4.00-4.06 (m, 1H), 5.03 (s, 2H), 5.05-5.12 (m, 2H), 5.71-5.84 (m, 1H), 7.35 (m, 5H), 7.53 (d, 1H), 12.57 (bs, 1H). Mass spectrometry analysis (APCI) showed m/z = 250 ([M+H]+).LC/MS analysis (Method A) showed a retention time of 2.30 min.
