[C:1]([O:5][C:6]([N:8]([CH2:28][C:29]([OH:31])=O)[C@@H:9]1[CH2:11][C@H:10]1[C:12]1[CH:17]=[CH:16][C:15]([O:18][CH2:19][C:20]2[CH:25]=[CH:24][C:23]([C:26]#[N:27])=[CH:22][CH:21]=2)=[CH:14][CH:13]=1)=[O:7])([CH3:4])([CH3:3])[CH3:2].[NH3:32]>C(Cl)Cl>[NH2:32][C:29](=[O:31])[CH2:28][N:8]([C@@H:9]1[CH2:11][C@H:10]1[C:12]1[CH:17]=[CH:16][C:15]([O:18][CH2:19][C:20]2[CH:25]=[CH:24][C:23]([C:26]#[N:27])=[CH:22][CH:21]=2)=[CH:14][CH:13]=1)[C:6](=[O:7])[O:5][C:1]([CH3:4])([CH3:2])[CH3:3]N,N′-Carbonyldiimidazole (27 mg, 0.17 mmol) was added to a solution of [(tert-butoxycarbonyl){(trans)-2-{4-[(4-cyanobenzyl)oxy]phenyl}cyclopropyl}amino]acetic acid (50 mg, 0.12 mmol) in dry CH2Cl2 (3 mL) at 0° C. (ice-water bath). The solution was stirred for 40 min at room temperature and cooled again at 0° C.; NH3 (25% aqueous solution, 0.05 mL, 0.60 mmol) was added and the reaction was allowed to reach room temperature and stirred for additional 1.5 h. The mixture was diluted with CH2Cl2 (20 mL) and washed with brine (10 mL) and HCl (10% aqueous solution, 1 mL). The organic layer was dried over anhydrous Na2SO4 and filtered. After removal of the solvent, the crude product was purified by column chromatography on silica gel (5% MeOH/CH2Cl2) affording 38 mg of tert-butyl 2-amino-2-oxoethyl[(trans)-2-{4-[(4-cyanobenzyl)oxy]phenyl}cyclopropyl]carbamate [Rf=0.6 (10% MeOH/CH2Cl2), colorless oil, 76% yield].
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