[C:1]([O:5][C:6]([NH:8][C@@H:9]([CH2:13][C:14]1[CH:19]=[CH:18][CH:17]=[C:16]([I:20])[CH:15]=1)[C:10](O)=[O:11])=[O:7])([CH3:4])([CH3:3])[CH3:2]>O1CCCC1>[C:1]([O:5][C:6](=[O:7])[NH:8][C@@H:9]([CH2:13][C:14]1[CH:19]=[CH:18][CH:17]=[C:16]([I:20])[CH:15]=1)[CH2:10][OH:11])([CH3:4])([CH3:2])[CH3:3]To a solution of (2S)-2-[(tert-butoxycarbonyl)amino]-3-(3-iodophenyl)propanoic acid [Aldrich] (4.0 g, 10. mmol) in tetrahydrofuran (10 mL) with stirring was added 1.0 M borane-THF complex in THF (40 mL) dropwise to keep temperature at 0° C. (about 15 min). The reaction mixture was stirred at room temperature for 1 h, then cooled down with ice-bath, quenched with AcOH:MeOH (1:5, 20 mL) and partitioned between saturated aqueous NaHCO3 solution and DCM, dried over sodium sulfate, filtered, and evaporated under reduced pressure. The residue was purified by combi-flash chromatography to give 2.0 g (52% yield) of the desired product. LC-MS found: 278.0 (M−Boc+H)+.
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