A solution of tert-butyl 4-(6-methoxy-3-oxo-2,3-dihydrobenzofuran-7-yloxy)piperidine-1-carboxylate (0.019 g, 0.052 mmol) in methanol (2.0 mL) was added with 1H-indazole-3-carboxaldehyde (0.008 g, 0.057 mmol). Then, the mixture was added with 5 drops of piperidine, and the mixture was stirred at room temperature for 2 hours. The reaction mixture was added with toluene, the solvent was evaporated under reduced pressure, and then the residue was purified by silica gel column chromatography (eluted with hexane/ethyl acetate (2:1→1:4)) to obtain tert-butyl (Z)-4-{2-[(1H-indazol-3-yl)methylene]-6-methoxy-3-oxo-2,3-dihydrobenzofuran-7-yloxy}piperidine-1-carboxylate (0.020 g, 79%).
