A mixture of 4-(5-bromo-2-ethylphenyl)-2,2,6,6-tetramethylpyran-3,5-dione (200 mg, 0.57 mmol), 3-fluorophenol (320 mg, 2.83 mmol), cesium carbonate (400 mg, 1.13 mmol), copper(II) trifluoromethanesulfonate (10 mg, 0.03 mmol), and powdered 3 Å molecular sieves (400 mg) in toluene (3.5 ml) is heated to 160° C. under microwave irradiation for 60 minutes. The mixture is cooled to room temperature, poured into 2M aqueous hydrochloric acid, diluted with dichloromethane and filtered through a phase separation cartridge. The organic phase is collected. The solvent is evaporated under reduced pressure and the residue is purified by column chromatography on silica gel to give 4-[2-ethyl-5-(3-fluorophenoxy)phenyl]-2,2,6,6-tetramethylpyran-3,5-dione.
