B(Br)(Br)Br.[Cl:5][C:6]1[CH:15]=[C:14]([O:16]C)[C:13]([Cl:18])=[C:12]2[C:7]=1[CH2:8][CH2:9][N:10](C(OC(C)(C)C)=O)[C:11]2=[O:19].O>ClCCl>[Cl:5][C:6]1[CH:15]=[C:14]([OH:16])[C:13]([Cl:18])=[C:12]2[C:7]=1[CH2:8][CH2:9][NH:10][C:11]2=[O:19]Boron tribromide (10 mL) was added to a cooled (0° C.) solution of tert-butyl 5,8-dichloro-7-methoxy-1-oxo-3,4-dihydroisoquinoline-2(1H)-carboxylate (296f, 14.5 g, 45.4 mmol) in dry dichloromethane (100 mL). The mixture was stirred at room temperature overnight, then water (10 mL) was added, causing a precipitate to form. The precipitate was collected by filtration, washed with water (500 mL), and dried to give 5,8-dichloro-7-hydroxy-3,4-dihydroisoquinolin-1(2H)-one (296g, 9.2 g, 95% yield) as a light yellow solid. 1H NMR (400 MHz, DMSO-d6): δ 10.58 (s, 1H), 8.17 (s, 1H), 7.13 (s, 1H), 3.25-3.23 (m, 2H), 2.83-2.80 (t, J=6.2 Hz, 2H). MS: 232 [M+1].
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