(E)-[2-(2-Propylbenzimidazol-1-yl)methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-ylidene]acetic acid (60 mg, 0.14 mmol) obtained in Example 2 was dissolved in DMF (0.6 mL), N,N′-carbonyldiimidazole (92 mg, 0.57 mmol) was added, and the mixture was stirred at room temperature for 1 hr. Methanesulfonamide (68 mg, 0.71 mmol) and DBU (106 μL, 0.71 mmol) were added to the reaction mixture, and the mixture was stirred at 80° C. for 2 hr. Water and 5% aqueous citric acid solution were added to the mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed with brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. Ethyl acetate was added to the residue, and the mixture was filtered to give the title compound (compound 12) (29 mg, 41%).
