[C:1]([O:5][C:6]([NH:8][C@H:9]([CH2:13][CH2:14][C:15]1[CH:20]=[CH:19][C:18]([C:21]([F:24])([F:23])[F:22])=[CH:17][CH:16]=1)[C:10]([OH:12])=O)=[O:7])([CH3:4])([CH3:3])[CH3:2].[NH2:25][C:26]1[CH:27]=[CH:28][C:29]2[C:33]([CH3:35])([CH3:34])[O:32][B:31]([OH:36])[C:30]=2[CH:37]=1.CCN(C(C)C)C(C)C.CN(C(ON1N=NC2C=CC=NC1=2)=[N+](C)C)C.F[P-](F)(F)(F)(F)F>C(Cl)Cl>[OH:36][B:31]1[C:30]2[CH:37]=[C:26]([NH:25][C:10](=[O:12])[C@H:9]([NH:8][C:6](=[O:7])[O:5][C:1]([CH3:4])([CH3:2])[CH3:3])[CH2:13][CH2:14][C:15]3[CH:20]=[CH:19][C:18]([C:21]([F:22])([F:24])[F:23])=[CH:17][CH:16]=3)[CH:27]=[CH:28][C:29]=2[C:33]([CH3:35])([CH3:34])[O:32]1To a suspension of (R)-2-(tert-butoxycarbonylamino)-4-(4-(trifluoromethyl)phenyl)butanoic acid (LXXI) (1 g, 2.88 mmol) and 6-amino-3,3-dimethylbenzo[c][1,2]oxaborol-1(3H)-ol (XCVIII) (0.615 g, 2.88 mmol) in dry DCM (10 mL) was added DIPEA (1.47 mL, 8.64 mmol). To this solution was added HATU (1.09 g, 2.88 mmol) and the mixture was stirred at room temperature overnight. The mixture was washed with 2 N aqueous HCl, 1 M aqueous K2CO3, brine, dried over MgSO4 and evaporated under vacuum to give (R)-tert-butyl 1-(1-hydroxy-3,3-dimethyl-1,3-dihydrobenzo[c][1,2]oxaborol-6-ylamino)-1-oxo-4-(4-(trifluoromethyl)phenyl)butan-2-ylcarbamate (1.44 g, 2.84 mmol, 99% yield). ESIMS found for C25H30BF3N2O5 m/z 507.5 (M+H).
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