To a round bottom flask was added tert-butyl {1-[4-(5-hydrazino-3-phenyl-1,6-naphthyridin-2-yl)phenyl]cyclobutyl}carbamate (1-6) (2.77 g, 5.75 mmol), and 1,1′-carbonylbis(1H-imidazole) (4.10 g, 4.40 mmol), in 1,4 Dioxane (30 mL). The sealed reaction mixture was then heated at 95° C. under an atmosphere of nitrogen. To the crude reaction mixture was added a saturated solution of sodium bicarbonate (100 mL) and ethyl acetate. The organic layer was washed with a saturated solution of sodium bicarbonate, followed by water, then brine, dried over sodium sulfate, filtered, and concentrated. The resulting residue was then purified by silica gel chromatography eluting with 0-10% IPA/DCM. The appropriate fractions were then combined and the solvent was removed in vacuo to give tert-butyl {1-[4-(3-hydroxy-9-phenyl[1,2,4]triazolo[3,4-f]-1,6-naphthyridin-8-yl)phenyl]cyclobutyl}carbamate (1-6a) as a tan solid. MS (M+H)+: observed=508.1, calculated=508.6.
