[Br:1][C:2]1[C:10]2[N:9]=[N:8][N:7]([CH2:11][C:12]([CH3:15])([CH3:14])[CH3:13])[C:6]=2[CH:5]=[CH:4][C:3]=1[O:16]C.B(Br)(Br)Br.O>ClCCl>[Br:1][C:2]1[C:10]2[N:9]=[N:8][N:7]([CH2:11][C:12]([CH3:14])([CH3:13])[CH3:15])[C:6]=2[CH:5]=[CH:4][C:3]=1[OH:16]To a solution of 4-bromo-1-(2,2-dimethylpropyl)-5-methoxy-1H-1,2,3-benzotriazole (1-5) (8.97 g, 30.1 mmol, 1.0 equiv.) in dichloromethane (150 ml) at 0° C., was added slowly a 1M solution of BBr3 (60.2 ml, 60.2 mmol, 2.0 equiv.) in dichloromethane. The reaction mixture was allowed to warm up to room temperature and was stirred for an additional 14 hours. LCMS showed completion. The reaction mixture was treated with water, neutralized to pH=7, then extracted with EtOAc. The combined organic layers were dried over Na2SO4, filtered and concentrated to give provide 4-bromo-1-(2,2-dimethylpropyl)-1H-1,2,3-benzotriazol-5-ol (1-6). 1H NMR (500 MHz, CDCl3) 7.36 (d, 1H, J=9.0 Hz), 7.24 (d, 1H, J=9.0 Hz), 4.37 (s, 2H), 1.04 (s, 9H) ppm. LRMS m/z (M+H) 283.9 and 285.9 (intensity ratio ˜1:1) found, 284.0 and 286.0 required.
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