To a mixture of 6-(2-cyanophenyl)-2-(3-fluorophenethylamino)-N-(pyrrolidin-2-ylmethyl)nicotinamide hydrochloride (95 mg, 0.2 mmol), 4-(tert-butoxycarbonylamino)butanoic acid (61 mg, 0.3 mmol), HOBT (41 mg, 0.3 mmol), and HBTU (114 mg, 0.3 mmol) were added DMF (1.0 mL) and DIEA (0.1 mL, 0.6 mmol). The reaction mixture was stirred at r.t. for 1 h. LC/MS indicated the reaction was complete. The reaction mixture was then filtered and the filtrate was purified on RP-HPLC using a mixture of acetonitrile and water to give tert-butyl 4-(2-((6-(2-cyanophenyl)-2-(3-fluorophenethylamino)nicotinamido)methyl)pyrrolidin-1-yl)-4-oxobutylcarbamate (81.2 mg, 65%). LRMS (M+H+) m/z 629.2.
