(E)-2-(2-Propylbenzimidazol-1-yl)methyl-5-(5-oxo-4,5-dihydro-1,2,4-oxadiazol-3-yl)methylene-10,11-dihydro-5H-dibenzo[a,d]cycloheptene (69 mg, 0.15 mmol) obtained in Example 5 and methanol (30 μL, 0.75 mmol) were dissolved in THF (1 mL), polymer-supported triphenylphosphine (150 mg, 0.45 mmol) and di-tert-butyl azodicarboxylate (104 mg, 0.45 mmol) were added at 0° C., and the mixture was stirred at room temperature for 1 hr. The mixture was filtered, and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane/ethyl acetate=7/3 to 0/10) to give the title compound (compound 6) (65 mg, 92%).
