A solution of Intermediate 6 (30 mg) in N,N-dimethylacetamide (1 ml) was added with K4[Fe(CN)6].3H2O (6.6 mg, Ald), sodium carbonate (5.5 mg), and palladium acetate (1.1 mg, WAKO), and stirred at 120° C. for 5 hours. The reaction mixture was added with water (3 ml), and ethyl acetate (3 ml×2) for extraction, and then successively washed with saturated aqueous sodium hydrogencarbonate, saturated aqueous ammonium chloride, and saturated brine, the organic layer was dried, and then the solvent was evaporated under reduced pressure. The residue was purified by column chromatography (Yamazen, n-hexane:ethyl acetate=3:1), and the solvent was evaporated under reduced pressure by using a rotary evaporator to obtain the title compound (yield: 10 mg).
