[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([C@H:8]([NH:13][C:14]2[CH:15]=[CH:16][C:17]([CH3:22])=[C:18]([CH:21]=2)[CH:19]=O)[C:9]([F:12])([F:11])[F:10])=[CH:4][C:3]=1[CH3:23].[NH:24]1[CH2:28][CH2:27][C@@H:26]([C:29]([OH:31])=[O:30])[CH2:25]1.CC(O)=O>CO>[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([C@H:8]([NH:13][C:14]2[CH:15]=[CH:16][C:17]([CH3:22])=[C:18]([CH:21]=2)[CH2:19][N:24]2[CH2:28][CH2:27][C@@H:26]([C:29]([OH:31])=[O:30])[CH2:25]2)[C:9]([F:11])([F:12])[F:10])=[CH:4][C:3]=1[CH3:23]To a solution of aldehyde INT 33 (2.50 g, 7.32 mmol) and (R)-pyrrolidine-3-carboxylic acid (0.93 g, 8.05 mmol) in MeOH (74 mL) was added HOAc (0.42 mL, 7.32 mmol) followed by PS—CNBH3 (2.5 mmol/g, 2.93 g, 7.32 mmol). The reaction mixture was stirred at room temperature overnight. The mixture was filtered through Celite. The filtrate was concentrated. The residue was taken up in EtOAc and washed with saturated aqueous NaHCO3 and water. The aqueous layers were extracted with EtOAc (2×). The combined organic layers were washed with brine, dried over MgSO4, filtered and concentrated. The residue was purified by chromatography on silica gel (CH2Cl2/MeOH) to afford the title compound Example 21.
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