[C:1]([O:5][C:6](=[O:29])[C@@H:7]([CH:26]([CH3:28])[CH3:27])[NH:8][S:9]([C:12]1[CH:17]=[CH:16][C:15]([O:18][C:19]2[CH:24]=[CH:23][C:22]([Br:25])=[CH:21][CH:20]=2)=[CH:14][CH:13]=1)(=[O:11])=[O:10])([CH3:4])([CH3:3])[CH3:2].C(=O)([O-])[O-].[K+].[K+].Cl.[N:37]1[CH:42]=[CH:41][CH:40]=[C:39]([CH2:43]Cl)[CH:38]=1.Cl.N1C=CC=CC=1CCl>CN(C=O)C.C(OCC)(=O)C.O>[C:1]([O:5][C:6](=[O:29])[C@@H:7]([CH:26]([CH3:27])[CH3:28])[N:8]([S:9]([C:12]1[CH:17]=[CH:16][C:15]([O:18][C:19]2[CH:20]=[CH:21][C:22]([Br:25])=[CH:23][CH:24]=2)=[CH:14][CH:13]=1)(=[O:11])=[O:10])[CH2:43][C:39]1[CH:38]=[N:37][CH:42]=[CH:41][CH:40]=1)([CH3:4])([CH3:3])[CH3:2]To a solution of N-[4-(4-bromophenoxy)benzenesulfonyl]-D-valine t-butyl ester (980 mg, 2.0 mol) in 5 mL of DMF was added potassium carbonate (1.53 g, 11.1 mol), 3-picolyl chloride hydrochloride (414 mg, 2.53 mol), and Kl (67 mg, 0.4 mol). The reaction was stirred at room temperature overnight. An additional 220 mg of picolyl chloride hydrochloride was added, and the reaction was stirred for 3 h. Water (25 mL) and ethyl acetate (50 mL) were added, and the layers were separated. The ethyl acetate fraction was washed with brine, dried over MgSO4, and concentrated. The residue was purified by chromatography on silica, eluting with 35% ethyl acetate in hexane, to give 1.07g (92%) of N-[4-(4-bromophenoxy)benzenesulfonyl]-N-(pyridin-3-yl)methyl-D-valine t-butyl ester as a tan foam.
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