In a volumetric flask molecular sieves of 4 Å (1 g, previously dried for 3 h at 200° C. under vacuum), 4,6-bis(4-fluorophenyl)-5-(4-pyridyl)-1H-pyrazolo[3,4-b]pyridine (0.30 g, 0.8 mmol, obtained in example 1), (4-methylsulfanylphenyl)boronic acid (0.26 g, 1.6 mmol), copper II acetate (0.28 g, 1.6 mmol), pyridine (0.12 g, 1.6 mmol), triethylamine (0.16 g, 1.6 mmol) and CH2Cl2 (22 mL) were introduced under argon atmosphere. This was stirred at room temperature for 2 days. It was filtered through celite and concentrated. The crude product obtained was purified by chromatography on silica gel using hexane-EtOAc mixtures of increasing polarity as eluent, to afford 40 mg of 4,6-bis(4-fluorophenyl)-2-(4-methylsulfanylphenyl)-5-(4-pyridyl)pyrazolo[3,4-b]pyridine (yield: 10%) and 90 mg of 4,6-bis(4-fluorophenyl)-1-(4-methylsulfanylphenyl)-5-(4-pyridyl)pyrazolo[3,4-b]pyridine (yield: 23%).
