[Synthesis]
The general procedure for the synthesis of (2S,3S)-2-amino-3-hydroxy-4-methylpentanoic acid from the compound (CAS: 228858-51-3) was as follows: the raw material (22 mg, 0.11 mmol, dr > 99:1) was dissolved in 6.0 M aqueous HCl (1 mL) and stirred at room temperature for 3 hours. Upon completion of the reaction, the mixture was concentrated in vacuum. Subsequently, water (4 mL) and chloroform (3 mL) were added, and the aqueous layer was washed with chloroform (23 mL) and again concentrated under vacuum. Purification by ion exchange chromatography (using DOWEX 50WX8-200 resin, eluent 1.0 M NH4OH aqueous solution) afforded the target product (2S,3S)-2-amino-3-hydroxy-4-methylpentanoic acid as a white solid (11 mg, 69% yield, dr 96:4). The physicochemical properties of the product are as follows: melting point 220-226 °C (decomposition); specific optical rotation [a]D20 +17.6 (c 1.0, H2O); literature value [a]D25 +20 (c 1.1, H2O); infrared spectrum (ATR) νmax 3449, 3058 (O-H, N-H), 1627 cm-1 (C=O); 1H NMR ( 500 MHz, D2O) δ 0.89 (3H, d, J = 6.7 Hz, C(4)-MeA), 0.90 (3H, d, J = 6.7 Hz, C(4)-MeB), 1.87 (1H, d septet, J = 9.1, 6.7 Hz, C(4)-H), 3.46 (1H, dd, J = 9.1, 3.2 Hz, C(3 )-H), 3.84 (1H, d, J = 3.2 Hz, C(2)-H); 13C NMR (125 MHz, CDCl3) δ 18.5, 18.5 (C(4)-Me2), 30.2 (C(4)), 57.1 (C(2)), 76.1 (C(3)), 171.7 (C(1)); mass spectra (ESI) m/z 148 ([M+H]+, 100%); high-resolution mass spectrum (ESI) C6H13NNaO3 ([M+Na]+) calculated value 170.0788, measured value 170.0788. |