A mixture of 4-bromo-3-fluoro(trifluoromethoxy)benzene (6.6 g, 26 mmol), benzophenone imine (6.4 mL, 38 mmol), Pd2(dba)3 (0.58 g, 0.64 mmol), Xantphos (1.5 g, 2.6 mmol) and sodium tert-butoxide (3.7 g, 38 mmol) in 1,4-dioxane (120 mL) was stirred at 100° C. under N2 atmosphere for 5 h. After stirring at room temperature overnight, the mixture was concentrated under reduced pressure. The residue was partitioned between AcOEt and water. The organic layer was washed with brine, dried over MgSO4, filtered and concentrated under reduced pressure. The residue was chromatographed on silica gel (0/100-5/95 AcOEt/hexane) to give a yellow oil. The residual oil was dissolved in THF (150 mL), and 1 M HCl aqueous solution (50 mL) was added to the mixture. After stirring at room temperature for 1 h, the mixture was basified with 8 M NaOH aqueous solution and extracted with diethyl ether. The organic layer was washed with brine, dried over MgSO4, filtered and concentrated under reduced pressure. The residue was chromatographed on silica gel (0/100-5/95 AcOEt/hexane) to give the title compound (4.2 g, 85% yield) as a pale yellow oil: 1H NMR (300 MHz, DMSO-d6): δ ppm 5.36 (2H, s), 6.75-6.85 (1H, m), 6.89-6.94 (1H, m), 7.12 (1H, dd, J=11.7, 2.3 Hz).
