[OH:1][C:2]1[CH:3]=[C:4]2[C:8](=[CH:9][CH:10]=1)[N:7]([CH2:11][C:12]([O:14][CH3:15])=[O:13])[CH:6]=[CH:5]2.[Br:16][CH2:17][CH2:18][CH2:19]Br.C([O-])([O-])=O.[Cs+].[Cs+]>CN(C=O)C>[Br:16][CH2:17][CH2:18][CH2:19][O:1][C:2]1[CH:3]=[C:4]2[C:8](=[CH:9][CH:10]=1)[N:7]([CH2:11][C:12]([O:14][CH3:15])=[O:13])[CH:6]=[CH:5]2To a solution of methyl (5-hydroxy-1H-indol-1-yl)acetate (1.0 g, 4.87 mmol) (Example 9) in 35 mL DMF, was added 1,3-dibromopropane (5.90 g, 29.24 mmol) and Cs2CO3 (3.18 g, 9.75 mmol). The mixture was stirred at rt for 6 h, and then the solvent was evaporated under reduced pressure. The residue was suspended in EtOAc, filtered, and the filter cake was washed with EtOAc. The combined organic layers were dried, concentrated, and purified by column chromatography (0-10% EtOAc in hexane) to give 720 mg (45%) of the product containing minor impurities. This material was used in later steps with no further purification. 1H NMR (400 MHz, CDCl3) δ 7.18-7.10 (m, 2H), 7.05 (d, 1H), 6.94-6.85 (m, 1H), 6.50 (d, 1H), 4.80 (s, 2H), 4.18 (t, 2H), 3.75 (s, 3H), 3.65 (t, 2H), 2.40-2.30 (m, 2H).
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