A solution of Intermediate 71 (313 mg) in toluene (6 ml) was added with tetrakis(triphenylphosphine)palladium(0) (17.9 mg, Aldrich), tetramethyltin (165 μl, Kanto Chemicals) and 2,6-di-tert-butyl-4-methylphenol (several pellets, Tokyo Kasei Kogyo) and stirred in a sealed tube at 150° C. for 48 hours. The reaction mixture was cooled to room temperature, filtered through Celite and concentrated under reduced pressure. The residue was added with saturated brine (30 ml) and extracted three times with ethyl acetate (30 ml for each time). The organic layers were combined and dried over anhydrous sodium sulfate, and then the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (hexane:ethyl acetate=2:1) to obtain the title compound (61.7 mg).
