To a stirred solution of 3-fluoro-4-(1,3-thiazol-4-yl)phenyl trifluoromethanesulfonate (1.45 g, 4.43 mmol) in dioxane (42 ml) was added tributyl(1-ethoxyvinyl)tin (1.92 g, 5.32 mmol), tetrakis(triphenylphosphine)palladium (512 mg, 0.44 mmol), lithium chloride (466 mg, 11.0 mmol), and the mixture was heated at reflux temperature for 16 hours. The reaction mixture was cooled down to room temperature, and diluted with ethyl acetate. The whole was washed with saturated potassium fluoride aqueous solution, and the precipitate was removed by filteration through celite. The resulting solution was extracted with ethyl acetate. The organic layer was concentrated in vacuo. To the residue was added THF (20 ml), 2N HCl aqueous solution (20 ml), and the mixture was heated at reflux temperature for 8 hours. The reaction mixture was cooled down to room temperature, made neutral by addition of NaHCO3, and extracted with ethyl acetate. The organic layer was washed with brine, dried over MgSO4, and concentrated in vacuo. The residue was purified by flash chromatography eluting with ethyl acetate-hexane (1:5) to give title compound (666 mg, 68% yield).
