To a solution (20 mL) of 1-(5-bromo-3-methyl-1-benzofuran-2-yl)-2-methylpropan-1-one (1.0 g) synthesized in Example A182(1) in toluene were added cyclopropaneboronic acid (0.92 g), 2N aqueous sodium carbonate solution (5.3 mL), and the mixture was stirred at room temperature for 10 min under argon atmosphere. To the reaction mixture were added 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (0.18 g) and tris(dibenzylideneacetone)dipalladium (0) (0.10 g), and the mixture was heated under reflux under argon atmosphere overnight. The reaction mixture was cooled to room temperature, and filtered through celite, and the residue was washed with diethyl ether. Water was added to the filtrate, and the organic layer was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate:hexane=1:10, volume ratio) to give the title object compound (0.80 g, 93%) as a yellow oil.
