A solution of 5-(methylsulfonyl)-1H-indazole-3-carboxaldehyde (0.0392 g, 0.175 mmol) in methanol (0.7 mL) was added with tert-butyl 4-[(6-methoxy-3-oxo-2,3-dihydrobenzofuran-7-yl)methyl]piperazine-1-carboxylate (0.0915 g, 0.252 mmol) synthesized in the same manner as that of Example B42, Step 5, and piperidine (0.00149 g, 0.0175 mmol), and the mixture was stirred at 60° C. for 2 hours. The reaction mixture was concentrated, and the resulting residue was purified by silica gel column chromatography (chloroform/methanol) to obtain tert-butyl (Z)-4-[(6-methoxy-2-{[5-(methylsulfonyl)-1H-indazol-3-yl]methylene}-3-oxo-2,3-dihydrobenzofuran-7-yl)methyl]piperazine-1-carboxylate (0.0470 g, 47%).
