[Synthesis]
General procedure for the synthesis of compounds (CAS: 84500-41-4) from (2S,3R)-2-(((benzyloxy)carbonyl)amino)-3-hydroxybutanoic acid and benzyl bromide: (2S,3R)-2- benzyloxycarbonylamino-3-hydroxybutanoic acid (1.0 g, 4.0 mmol) was dissolved in a mixture of N,N-dimethylformamide (DMF, 15.0 mL) and deionized water (5.0 mL) in a mixed solvent, cesium carbonate (644.5 mg, 2.0 mmol) was added, and the reaction was stirred for 30 min at room temperature. After the reaction was completed, the reaction solution was concentrated and the residual water was removed by azeotropy with toluene (3 × 10 mL). Subsequently, a solution of benzyl bromide (0.71 mL, 5.9 mmol) in DMF (10.0 mL) was added to the dried residue and the reaction was continued for 24 hours. At the end of the reaction, the reaction was quenched by the addition of water (15 mL) and extracted with ethyl acetate (2 x 30 mL). The organic phases were combined, dried over anhydrous sodium sulfate, filtered and concentrated. The crude product was purified by fast column chromatography with ethyl acetate/hexane (1:3, v/v) as eluent to give the target compound (1.149 g, 84% yield) as a white powder. The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3), 13C NMR (125 MHz, CDCl3) and LC-ESI-MS: 1H NMR (400 MHz, CDCl3) δ 7.26-6.35 (m, 10H), 5.60 (d, 1H, J = 8.7 Hz), 5.17-5.24 (m, 2H) 5.13 (s, 2H), 4.37-4.39 (m, 2H), 1.97 (br, 1H), 1.63 (br, 1H), 1.23 (d, 1H, J = 6.3 Hz); 13C NMR (125 MHz, CDCl3) δ 171.2, 156.9, 136.2, 135.3, 128.6, 128.5, 128.5 128.5, 128.2, 128.0, 68.0, 67.4, 67.2, 59.5, 19.9; LC-ESI-MS [M + H]+ C19H21NO5 Calculated value 344.14, measured value 344.03. |