The product obtained using (E)-4-[2-(1H-indazol-3-yl)vinyl]benzoic acid (300 mg, 1.00 mmol) obtained in Step 6 of Example 1, N-(2-aminoethyl)carbamic acid tert-butyl ester (240 mg, 1.50 mmol), 1-hydroxybenzotriazole monohydrate (176 mg, 1.30 mmol), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (270 mg, 1.40 mmol) and N-methylmorpholine (0.22 mL, 2.00 mmol) in a similar manner to Example 5, was dissolved in methanol (2.00 mL), and the solution was added with 4 mol/L hydrogen chloride-methanol solution (1.50 mL), followed by heating under reflux at 60° C. for 30 minutes. The reaction mixture was concentrated under reduced pressure, and the residue was crystallized from acetone to obtain Compound III (206 mg, 54%).
