[OH:1][CH2:2][CH:3]([NH:8][C:9](=[O:15])[O:10][C:11]([CH3:14])([CH3:13])[CH3:12])[CH2:4][CH:5]([CH3:7])[CH3:6].[Br:16][CH2:17][CH2:18][CH2:19][C:20](O)=[O:21].C(Cl)CCl>C(Cl)Cl.CN(C1C=CN=CC=1)C>[Br:16][CH2:17][CH2:18][CH2:19][C:20]([O:1][CH2:2][CH:3]([NH:8][C:9]([O:10][C:11]([CH3:13])([CH3:12])[CH3:14])=[O:15])[CH2:4][CH:5]([CH3:7])[CH3:6])=[O:21]tert-Butyl 1-hydroxy-4-methylpentan-2-ylcarbamate (2.00 g, 9.20 mmol) and 4-bromo-butyric acid (2.57 g, 15.38 mmol) were dissolved in CH2Cl2 (40 ml) and the mixture was cooled to 0° C. EDC (4.20 g, 21.90 mmol) and DMAP (0.27 g, 2.21 mmol) were added and the reaction was slowly warmed to room temperature and stirred overnight. Then the reaction was treated with a solution of 5% aqueous NaH2PO4 (100 ml). The organic layer was washed with a solution of 10% aqueous Na2CO3 (100 ml) and brine, dried over Na2SO4, filtered and concentrated. The obtained crude clear oil corresponding to the title compound (3.30 g) was used without any further purification.
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