A solution of tert-butyl 4-[4-(6-methoxy-3-oxo-2,3-dihydrobenzofuran-7-yl)but-3-enyl]piperidine-1-carboxylate (0.0265 g, 0.0660 mmol) in methanol (3 mL) was added with 1H-indazole-3-carboxaldehyde (0.00964 g, 0.0660 mmol) and piperidine (0.0800 mL, 0.810 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 4-((Z)-4-{(Z)-2-[(1H-indazol-3-yl)methylene]-6-methoxy-3-oxo-2,3-dihydrobenzofuran-7-yl}but-3-enyl)piperidine-1-carboxylate (0.0293 g, 84%).
