A mixture of (1E,4E)-2-(tert-butoxycarbonylamino)-8-(4-(pyrrolidine-1-carbonyl)phenyl)-3H-benzo[b]azepine-4-carboxylic acid (200 mg, 0.42 mmol), HOBt (114 mg, 0.84 mmol), and EDCI (161 mg, 0.84 mmol) in DMF (5 mL) was stirred for 1 h at room temperature. To this mixture was added triethylamine (0.12 mL, 0.84 mmol) and propan-1-amine (0.043 mL, 0.53 mmol) at room temperature. The resulting solution was stirred for additional 2 h. The reaction mixture was diluted with EtOAc (5 mL) and washed with sat'd aq NH4Cl. The aqueous layer was separated and extracted with EtOAc (3×5 mL). The combined organic layers were washed with brine (5 mL), sat'd aq NaHCO3 (5 mL), and brine (5 mL). The organic layer was dried over MgSO4, filtered, and concentrated under reduced pressure to give the crude tert-butyl (1E,4E)-4-(propylcarbamoyl)-8-(4-(pyrrolidine-1-carbonyl)phenyl)-3H-benzo[b]azepin-2-ylcarbamate that was used directly without further purification.
