A solution of 0.4N 9-borabicyclo[3.3.1]nonane in tetrahydrofuran (300 ml, 0.12 mol) was added dropwise to a solution of methyl 3-butenoate (12.01 g, 0.12 mol) in tetrahydrofuran (5 ml) at room temperature under nitrogen atmosphere, and the mixture was stirred for 3 hours. This reaction mixture was added dropwise to a solution of 2-[4-(3-bromophenyl)-7-chloro-6-methyl-2-oxo-2H-chromen-3-yl]-N-[4-fluoro-2-(trifluoromethyl)phenyl]acetamide obtained in Reference Example 4 (34.12 g, 0.06 mol), sodium methoxide (9.72 g, 0.18 mol) and (1,1′-bis-(diphenylphosphino)ferrocene)palladium dichloride (9.8 g, 0.012 mol) in tetrahydrofuran (150 ml) at room temperature under nitrogen atmosphere, and the mixture was refluxed for 17 hours. To the reaction mixture was added an aqueous solution of 1N hydrochloric acid, and the mixture was extracted with ethyl acetate. The extract was washed with water and saturated saline, and dried over magnesium sulfate. The extract was concentrated, and roughly purified by silica gel column chromatography to obtain a crude product of methyl 4-{3-[7-chloro-3-(2-{[4-fluoro-2-(trifluoromethyl)phenyl]amino}-2-oxoethyl)-7-methyl-2-oxo-2H-chromen-4-yl]phenyl}butanoate (34.96 g). This was dissolved in a mixed solvent of ethanol (300 ml) and tetrahydrofuran (300 ml), an 2N aqueous solution of sodium hydroxide (118.5 ml, 0.237 mol) was added thereto, and the mixture was stirred at room temperature for 12 hours. The reaction mixture was extracted with water. The extract was washed with diethyl ether, neutralized with 6N hydrochloric acid, and extracted with ethyl acetate. The extract was washed with saturated saline, dried over magnesium sulfate, and concentrated. The residue was purified by column chromatography and then re-crystallized from acetonitrile to obtain the title compound (12.04 g): mp 196° C.
