[Br:1][C:2]1[CH:7]=[CH:6][C:5]([OH:8])=[C:4]([C:9]2[N:10]=[CH:11][NH:12][CH:13]=2)[CH:3]=1.C(N(CC)CC)C.[C:21](Cl)(=[O:26])[C:22]([CH3:25])([CH3:24])[CH3:23].O>ClCCl.CN(C1C=CN=CC=1)C>[C:21]([O:8][C:5]1[CH:6]=[CH:7][C:2]([Br:1])=[CH:3][C:4]=1[C:9]1[N:10]=[CH:11][NH:12][CH:13]=1)(=[O:26])[C:22]([CH3:25])([CH3:24])[CH3:23]
To a solution of 4-bromo-2-(1H-imidazol-4-yl)phenol (2.9 g, 12.13 mmol) in dichloromethane was added DMAP (296 mg, 2.43 mmol), triethylamine (5.1 mL, 36.4 mmol) and pivaloyl chloride (3.7 mL, 30.33 mmol). The reaction was stirred at room temperature for 16 h. The reaction mixture was poured into water (100 mL) and extracted with dichloromethane (2×100 mL). The combined organic layers were dried over sodium sulfate and concentrated. The crude product was dissolved in methanol (70 mL) and refluxed for 2 h. The solution was concentrated and the residue was purified by flash column chromatography (silica gel, 20%-70% EtOAc/hexanes as eluent) to afford the desired product as yellow solid (1.2 g, 3.72 mmol, 31%). 1H NMR: 1.35 (s, 9H), 6.90 (d, 1H, J=8.4 Hz), 7.31 (s, 1H), 7.38 (dd, 1H, J=8.4 Hz, 2.4 Hz), 7.67 (s, 1H), 8.00 (d, 1H, J=2.4 Hz).
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