1-Hydroxybenzotriazole → 2-bromo-4-[[[(1H-indol-4-yl)methyl]amino]carbonyl]benzoic acid methyl ester

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Reaction Steps

Diisopropylethylamine (2.3 mL, 13.2 mmol) was added dropwise to a solution of 2-bromo-1,4-benzenedicarboxylic acid, 1-methyl ester (Example 2; 861 mg, 3.32 mmol), HBTU (1.39 g, 3.65 mmol), 1H-indole-4-methanamine hydrochloride salt (Example 11; 528 mg, 3.98 mmol), and HOBT (493 mg, 3.65 mmol) in N,N-dimethylformamide (6.5 mL) at 0° C. The solution warmed to room temperature and stirred for 24 h. The solvent was concentrated under vacuum to remove most of the N,N-dimethylformamide. The residue was diluted with ethyl acetate (50 mL) and washed with 1 M HCl (10 mL), water (10 mL), saturated aqueous NaHCO3 (10 mL) and brine (10 mL). The organic layer was dried (MgSO4), filtered, evaporated and flash chromatographed (silica, 25-35% ethyl acetate/petroleum ether) to give 2-bromo-4-[[[(1H-indol-4-yl)methyl]amino]carbonyl]benzoic acid, methyl ester (900 mg, 70%) as an off-white solid.

Provenance & Evidence