To a mixture of 4′-methyl-5-(methylsulfonyl)biphenyl-3-carboxylic acid (40 mg, 0.14 mmol), N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (53 mg, 0.28 mmol), 1-hydroxybenzotriazole hydrate (21 mg, 0.14 mmol), and CH2Cl2 (3 mL) were added (6-methylpyridin-3-yl)methanamine (25 mg, 0.21 mmol), and N,N-diisopropylethylamine (48 μL, 0.28 mmol). The mixture was stirred at room temperature overnight and then concentrated. The residue was purified by preparative HPLC (100×20.2 mm, C18 column; 30-80% CH3CN-water[10 mM Et2NH]) to afford a white solid.
