1-Hydroxybenzotriazole → N-[2-bromo-4-[[[(3-hydroxyphenyl)methyl]amino]carbonyl]benzoyl]-3-(thiophene-2-carbonyl)amino-L-alanine methyl ester

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Reaction Steps

Diisopropylethylamine (305 μL, 1.71 mmol) was added dropwise to a solution of 2-bromo-4-[[[(3-hydroxyphenyl)methyl]amino]carbonyl]benzoic acid (Example 47; 150 mg, 0.428 mmol), HBTU (179 mg, 0.471 mmol), 3-(thiophene-2-carbonyl)amino-L-alanine methyl ester HCl salt (Example 301; 125 mg, 0.471 mmol), and HOBT (64 mg, 0.471 mmol) in N,N-dimethylformamide (6.5 mL) at 25° C. The solution was stirred for 6 h. The solvent was concentrated under vacuum to remove most of the N,N-dimethylformamide. The residue was diluted with ethyl acetate (60 mL) and washed with 1 N 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, 60–75% ethyl acetate in petroleum ether) to give N-[2-bromo-4-[[[(3-hydroxyphenyl)methyl]amino]carbonyl]benzoyl]-3-(thiophene-2-carbonyl)amino-L-alanine, methyl ester (198 mg, 83%) as an off-white foam.

Provenance & Evidence