Compound (154e) (1.66 g), copper(I) oxide (0.070 g), 4,7-dimethoxy-1,10-phenanthroline (0.214 g), cesium carbonate (5.46 g), polyethylene glycol (Mn=3400) (0.250 g), and 4-(1-methyl-1H-pyrazol-4-yl)-1H-imidazole hydrochloride (1.20 g) were suspended in DMSO (15 mL), followed by stirring at 120° C. for 2 hr. The reaction solution was diluted with ethyl acetate, and insoluble matters were filtered by celite. The filtrate was distributed between ethyl acetate and water, and the organic layer was washed with saturated saline. The organic layer after the washing was dried over anhydrous sodium sulfate, and the solvent was distilled away to obtain 3-methyl-4-{4-(4-(1-methyl-1H-pyrazol-4-yl)-1H-imidazol-1-yl)-3-(trifluoromethyl)-1H-pyrazolo[3,4-b]pyridin-1-yl}benzonitrile, which was used in the subsequent reaction without being purified. TFA (5.0 mL) and sulfuric acid (0.5 mL) were added to this 3-methyl-4-{4-(4-(1-methyl-1H-pyrazol-4-yl)-1H-imidazol-1-yl)-3-(trifluoromethyl)-1H-pyrazolo[3,4-b]pyridin-1-yl}benzonitrile, followed by stirring at room temperature for 2 days. The reaction solution was cooled in an ice bath and was neutralized with sodium hydroxide. The reaction solution was distributed between ethyl acetate and water, and the organic layer was washed with saturated saline. The organic layer after the washing was dried over anhydrous sodium sulfate, and the solvent was distilled away. Ethanol was added to the residue, and the precipitate was collected by filtration and dried under reduced pressure to obtain compound (154) (0.881 g, the second stage yield: 38%).
