To a solution of 2-methyl-2H-indazole-5-carboxyllic acid (28 mg, 0.16 mmol) in dry dimethylformamide was added 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (37 mg, 0.19 mmol) and 1-hydroxybenzotriazole (26 mg, 0.19 mmol) N,N-diisopropylethylamine (84 μL, 0.48 mmol). The reaction mixture was stirred at room temperature for 10 minutes and then 1′-isopropyl-4′,6′-dihydrospiro[piperidine-4,6-pyrazolo[3,4-c]pyridin]-7′(1′H)-one hydrochloride was added (Intermediate 2, 30 mg, 0.12 mmol) and the reaction was stirred for 16 hours. The mixture was poured into chilled water and the resulting precipitate was collected by vacuum filtration. The obtained solid was triturated from diethyl ether to afford 1′-isopropyl-1-(2-methyl-2H-indazole-5-carbonyl)-4′,6′-dihydrospiro[piperidine-4,5′-pyrazolo[3,4-c]pyridin]-7′(1′H)-one (25 mg). +ESI (M+H) 407.3; 1H NMR (400 MHz, DMSO-d6, δ): 8.41 (s, 1H), 7.85 (s, 1H), 7.75 (s, 1H), 7.63 (d, 1H), 7.40 (s, 1H), 7.20 (s, 1H), 5.40 (m, 1H), 4.18 (s, 3H), 3.60 (br. s., 4H), 2.85 (s, 2H), 1.70 (br. s., 4H), 1.35 (d, 6H).
