Intermediate 1a (228 mg) obtained in Example 1-1, Step A was added with phenylboronic acid (122 mg, Aldrich), tetrakis(triphenylphosphine)palladium(0) (116 mg), 1,2-dimethoxyethane (5 ml) and 2 N aqueous sodium carbonate (2 ml), and the mixture was refluxed by heating for 5 hours under a nitrogen gas atmosphere. The reaction mixture was cooled to room temperature, then added with water (25 ml), and extracted 3 times with ethyl acetate (20 ml for each time), and the combined organic layer was washed with saturated brine (30 ml), and dried over anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure, and the residue was purified by silica gel chromatography (n-hexane:ethyl acetate=2:1) to obtain the title compound (158 mg).
