A mixture of 3-((4-(difluoromethoxy)phenyl)ethynyl)phenol (900 mg), potassium carbonate (636 mg), Aliquat 336 (4 drops), sodium iodide (catalytic) and 4-bromo-1,1-difluoro-1-butene (591 μL) in methyl ethyl ketone was placed in a pressure vessel, heated at 80° C. for 15 h, cooled to room temperature, diluted with dichloromethane and filtered. The filtrate was concentrated in vacuo. The resultant residue was purified by flash chromatography (silica gel, eluant: 2.5% ethyl acetate/hexane to afford 1-(4,4-difluorobut-3-enyloxy)-3-((4-(difluoromethoxy)phenyl)ethynyl)benzene, 560 mg (46.2% yield); 1H NMR (chloroform-d1): δ 7.51 (d, J=8.8 Hz, 2H), 7.24 (m, 1H), 7.10 (m, 1H), 7.08 (d, J=8.8 Hz, 2H), 7.03 (m, 1H), 6.87 (m, 1H), 6.52 (t, J=73.5 Hz, 1H), 4.32 (m, 1H), 3.97 (t, J=6.4 Hz, 2H) and 2.47 (m, J=6.4 Hz, 2H); MS (ES pos) m/z 350.
