Br[CH2:2][C:3]1[C:4]([C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=2)=[N:5][O:6][C:7]=1[C:8]([O:10][CH2:11][CH3:12])=[O:9].[CH2:19]([O:21][C:22](=[O:36])[CH2:23][NH:24][CH2:25][C:26]1[CH:31]=[CH:30][C:29]([O:32][CH3:33])=[CH:28][C:27]=1[O:34][CH3:35])[CH3:20].C(=O)([O-])[O-].[K+].[K+].CCOC(C)=O>CN(C=O)C.O>[CH3:35][O:34][C:27]1[CH:28]=[C:29]([O:32][CH3:33])[CH:30]=[CH:31][C:26]=1[CH2:25][N:24]([CH2:2][C:3]1[C:4]([C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=2)=[N:5][O:6][C:7]=1[C:8]([O:10][CH2:11][CH3:12])=[O:9])[CH2:23][C:22]([O:21][CH2:19][CH3:20])=[O:36]Ethyl 4-(bromomethyl)-3-phenylisoxazole-5-carboxylate (28.1 g, 90.6 mmol) was dissolved in 200 mL of DMF. N-(2,4-dimethoxybenzyl)glycine ethyl ester (22.9 g, 90.6 mmol) and potassium carbonate (9.2 g, 66.4 mmol) were added, and the mixture was stirred at room temperature for 16 h. EtOAc (200 mL) and water (100 mL) were added and the aqueous layer was extracted with additional EtOAc. The combined organic layer was washed with water and brine, and dried over MgSO4. After solvent was removed in vacuo, the crude product was purified by flash chromatography (0-40% EtOAc/hexanes) to give 29.6 g of the title compound. MS: (+) m/z 483.73 (M+1).
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