[C:1]([O:5][C:6]([CH:8]1[CH2:14][CH2:13][C:12]2[CH:15]=[CH:16][C:17]([O:19][CH3:20])=[CH:18][C:11]=2[N:10]([CH2:21][CH3:22])[C:9]1=[O:23])=[O:7])([CH3:4])([CH3:3])[CH3:2].[Br:24]N1C(=O)CCC1=O>C(O)(=O)C.C(Cl)(Cl)Cl>[Br:24][C:16]1[C:17]([O:19][CH3:20])=[CH:18][C:11]2[N:10]([CH2:21][CH3:22])[C:9](=[O:23])[CH:8]([C:6]([O:5][C:1]([CH3:4])([CH3:3])[CH3:2])=[O:7])[CH2:14][CH2:13][C:12]=2[CH:15]=1A solution of 3(R,S)-tert-butoxycarbonyl-1-ethyl-8-methoxy-2,3,4,5-tetrahydro-1H-1-benzazepine-2-one (3.38 g, 10.58 mmol) and N-bromosuccinimide (2.072 g, 11.64 mmol) in acetic acid (2.5 mL) and chloroform (25 mL) was heated at reflux for 2 hrs. The reaction mixture was diluted with chloroform (25 mL), washed with saturated aqueous solution of NaHCO3 and water, dried over Na2SO4, filtered and evaporated to dryness. Purification of the crude product by flash chromatography on silica gel column eluted with EtOAc/hexane (3:7) provided the desired compound (3.25 g, 77%) as white powder.
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