3′-Fluoro-4′-[(6-fluoro-1,3-benzothiazol-2-yl)amino]biphenyl-4-carboxylic acid (0.084 g, 0.22 mmol) and L-valine methyl ester hydrochloride (0.044 g, 0.26 mmol) were suspended in CH2Cl2 (5 mL), and triethylamine (0.04 mL, 0.26 mmol), 1-hydroxybenzotriazole (0.0296 g, 0.22 mmol), and N,N′-diisopropylcarbodiimide (0.030 mL, 0.22 mmol) were added. DMF (2.0 mL) was added to achieve dissolution, and the reaction mixture was stirred at rt overnight. The reaction mixture was diluted with EtOAc (50 mL) and was washed with water (2×50 mL) and brine (50 mL). The combined organic phases were dried over MgSO4, filtered, and concentrated in vacuo. The crude material was purified by flash column chromatography (Biotage® system; 30-40% EtOAc/Hexanes gradient). This yielded 90.4 mg (83%) of the desired product as a white solid.
