[C:1]([O:5][C:6]([NH:8][C@H:9]([CH2:14][C:15]1[CH:20]=[CH:19][C:18]([B:21]2[O:25][C:24]([CH3:27])([CH3:26])[C:23]([CH3:29])([CH3:28])[O:22]2)=[CH:17][CH:16]=1)[C:10](OC)=[O:11])=[O:7])([CH3:4])([CH3:3])[CH3:2].[BH4-].[Li+]>O1CCCC1>[OH:11][CH2:10][C@H:9]([NH:8][C:6](=[O:7])[O:5][C:1]([CH3:4])([CH3:3])[CH3:2])[CH2:14][C:15]1[CH:16]=[CH:17][C:18]([B:21]2[O:25][C:24]([CH3:26])([CH3:27])[C:23]([CH3:29])([CH3:28])[O:22]2)=[CH:19][CH:20]=1Methyl (2R)-2-[(tert-butoxycarbonyl)amino]-3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]propanoate (9.50 g, 0.0234 mol) was dissolved in tetrahydrofuran (30 mL, 0.37 mol) and cooled to 0° C. 2 M lithium tetrahydroborate in tetrahydrofuran (12.0 mL) was added over 3 minutes. The reaction was allowed to stir in the ice bath for 21 minutes. The bath was removed and the reaction continued stirring for additional 3 hours. The reaction was quenched with saturated aqueous ammonium chloride. The mixture was extracted with ethyl acetate. The combined organic extracts were washed with brine and dried over Na2SO4. The solution was filtered through a glass frit and the solvent concentrated to give a white solid (8.80 g, 100%). 1H NMR (400 MHz, CDCl3): δ 7.75 (d, J=8.8 Hz, 2H), 7.23 (d, J=8.8 Hz, 2H), 4.73 (br s, 1H), 3.86 (br s, 1H), 3.66 (m, 1H), 3.54 (m, 1H), 2.87 (m, 2H), 1.42 (s, 9H), 1.34 (s, 12H).
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