To a mixture of tert-butyl {1-[4-(8-hydrazino-3-phenyl-1,7-naphthyridin-2-yl)phenyl]cyclobutyl}carbamate (7-5) (30 mg, 0.0620 mmol), acetic acid (11.2 mg, 0.187 mmol), HOBt (19.1 mg, 0.125 mmol) and DIPEA (0.044 mL, 0.249 mmol) in NMP (2 mL) was added EDC (219 mg, 0.125 mmol). The mixture was stirred at room temperature for 30 min and then at 100° C. for 72 hours. The mixture was diluted with AcOEt, washed with water, dried over sodium sulfate, filtered, and concentrated in vacuo. The residue was purified by silica gel chromatography. HCl in MeOH was added to the residue and the mixture was heated in a microwave reactor at 80° C. for 5 minutes. The solvent was evaporated and the residue was purified by reverse phase HPLC (H2O/0.1% TFA aq.-MeCN/0.1% TFA aq.) to give 1-[4-(3-methyl-8-phenyl[1,2,4]triazolo[4,3-h]-1,7-naphthyridin-9-yl)phenyl]cyclobutanamine (9-1) as a pale yellow solid.
