To a solution of 1′-isopropyl-4′,6′-dihydrospiro[piperidine-4,5′-pyrazolo[3,4-c]pyridin]-7′(1′H)-one hydrochloride salt (Intermediate 2, 430 mg, 1.3 mmol) and 3,7-dimethyl-1H-indazole-5-carboxylic acid (306 mg, 1.6 mmol) in dimethylformamide (2 mL) was added triethylamine (0.75 mL, 5.4 mmol), 4-dimethylaminopyridine (33 mg, 0.37 mmol), and 1-propanephosphonic acid cyclic anhydride (0.52 mL, 1.74 mmol, 50% solution in ethyl acetate), and the reaction mixture was stirred overnight at room temperature. The reaction mixture was concentrated in vacuo, taken up in ethyl acetate and washed with saturated aqueous sodium bicarbonate. The organic layer was dried over sodium sulfate, filtered, and concentrated to a solid. The solid was purified via flash column chromatography (0-15% methanol/dichloromethane) to afford a glassy solid. The glassy solid was stirred in ethyl acetate for 16 hours and the resulting solid collected by vacuum filtration to afford the desired product as a white solid (138 mg). +ESI (M+H) 421.0; 1H NMR (400 MHz, CD3OD, δ): 7.65 (s, 1H) 7.42 (s, 1H) 7.21 (s, 1H) 5.50 (m, 1H) 3.95 (br. s., 1H) 3.50-3.62 (br. s., 3H) 2.97 (s, 2H) 2.56 (m, 6H) 1.83 (br. s., 4H) 1.44 (d, 6H).
