To toluene 3.0 mL suspension of tert-butyl 2-amino-4-(3-(tert-butoxycarbonyloxy)phenyl)benzoate 0.12 g and cesium carbonate 0.25 g were added 5-bromobenzothiophene 0.13 g, 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl 7.4 mg, tris(dibenzylideneacetone)dipalladium(0) 2.9 mg and palladium acetate 1.4 mg at room temperature, and it was stirred at 110° C. for 24 hours. 2-Dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl 7.4 mg, tris(dibenzylideneacetone)dipalladium(0) 2.9 mg and palladium acetate 1.4 mg were added to it, and it was stirred at 110° C. for 21 hours. Cesium carbonate 51 mg, 5-bromobenzothiophene 33 mg, 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl 7.4 mg, tris(dibenzylideneacetone)dipalladium(0) 2.9 mg and palladium acetate 1.4 mg were added to it, and it was stirred at 110° C. for 24 hours. After the reaction mixture was cooled to room temperature, ethyl acetate and 10% citric acid aqueous solution were added to it, and insoluble matter was filtrated. The organic layer was separated and collected,dried over anhydrous magnesium sulfate after washing with saturated sodium chloride aqueous solution, and the solvent was removed under reduced pressure. The obtained residue was refined by silica gel column chromatography [Trikonex company, Flash Tube 2008, eluent; hexane:ethyl acetate=10:1] to give tert-butyl 2-((benzothiophen-5-yl)amino)-4-(3-(tert-butoxycarbonyloxy)phenyl)benzoate.
