To a mixture of 4-chlorophenol (0.473 g, 3.69 mmol), cesium carbonate (0.521 g, 1.48 mmol), copper triflate (0.013 g, 0.04 mmol) and powdered 5 Å molecular sieves (0.400 g) is added a solution of 2-(5-bromo-2-trifluoromethoxyphenyl)cyclopentane-1,3-dione (0.249 g, 0.74 mmol) in anhydrous toluene (3.5 ml). The mixture is flushed with nitrogen and heated at 160° C. for 1 hour under microwave radiation, then for a further 1 h at 170° C. After cooling to room temperature the crude product is partitioned between dichloromethane (5 ml) and 2M hydrochloric acid (5 ml), and the organic phase is separated then concentrated in vacuo. The residue is then purified by flash column chromatography on silica gel (ethyl acetate/iso-hexane eluant) to afford 2-[5-(4-chlorophenoxy)-2-trifluoromethoxyphenyl]cyclopentane-1,3-dione as a white solid.
