[CH3:1][O:2][C:3](=[O:14])[C@H:4]([OH:13])[C@H:5]([C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1)[NH2:6].Cl[C:16]([O:18][CH2:19][C:20]1[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=1)=[O:17]>N1C=CC=CC=1.CN(C1C=CN=CC=1)C.C(OCC)(=O)C>[CH3:1][O:2][C:3](=[O:14])[C@H:4]([OH:13])[C@H:5]([C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1)[NH:6][C:16]([O:18][CH2:19][C:20]1[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=1)=[O:17]A solution of (2R,3S)-β-phenyl isoserine methyl ester (2) (Preparation 1, 2 mM) in pyridine containing a small amount of DMAP is cooled in an ice bath and treated with benzyl chloroformate (0.8 ml). After stirring at room temperature overnight, the reaction is diluted with ethyl acetate, washed with 5% aqueous sodium bisulfate, dried and evaporated. The product is obtained pure by silica gel chromatography in ethyl acetate-hexane mixtures. Mp 120-121° C. NMR(CDCl3, TMS): δ3.26 (m, 1H); 3.79 (s, 3H); 4.47 (m, 1H); 5.06 (m, 2H); 5.27 (d, 1H); 5.75 (m, 1H); 7.20-7.50 (m, 10 H).
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