[C:1]([O:5][C:6]([N:8]1[C:16]2[C:11](=[C:12]([Cl:18])[C:13]([CH3:17])=[CH:14][CH:15]=2)[CH:10]=[CH:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2].C1C(=O)N([Br:26])C(=O)C1.CC(N=NC(C#N)(C)C)(C#N)C>C(Cl)(Cl)(Cl)Cl.CCOC(C)=O>[C:1]([O:5][C:6]([N:8]1[C:16]2[C:11](=[C:12]([Cl:18])[C:13]([CH2:17][Br:26])=[CH:14][CH:15]=2)[CH:10]=[CH:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2]
To a stirred solution of 314 (38.1 g, 0.143 mol) in CCl4 (300 mL) at 80° C. was added NBS (30.6 g, 0.172 mol) followed by AIBN (1.2 g, 7.31 mmol), and the reaction mixture was stirred at 80° C. overnight. The cooled reaction mixture was diluted with EtOAc, and the organic layer was washed with water and brine, dried (Na2SO4), filtered, and concentrated in vacuo. The crude product was purified by SiO2 chromatography eluting with an EtOAc/hexane gradient (2 to 20% EtOAc) to afford 16.1 g (33%) of tert-butyl-5-(bromomethyl)-4-chloro-1H-indole-1-carboxylate (316) as a white solid: NMR (400 MHz, CDCl3) δ 8.03 (d, J=8.4 Hz, 1H), 7.63 (s, 1H), 7.36 (d, J=8.4 Hz, 1H), 6.71 (d, J=3.8 Hz, 1H), 4.75 (s, 2H), 1.67 (s, 9H).
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