To a mixture of 4-(5-bromo-2-ethylphenyl)-2,2,6,6-tetramethylpyran-3,5-dione (0.278 g, 0.79 mmol), cesium fluoride (1.19 g, 7.90 mmol), 4-chloro-2-fluorophenylboronic acid (0.194 g, 1.11 mmol) and [1,1′-bis(diphenylphosphino)ferrocene]dichloro-palladium(II) (0.102 g, 0.12 mmol) is added degassed dimethoxyethane (2 ml), and the resulting suspension is stirred under nitrogen for 45 minutes then heated at 80° C. for 20 hours. After cooling to room temperature the reaction mixture is partitioned between ethyl acetate and 1M aqueous hydrochloric acid. The aqueous phase is further extracted with ethyl acetate, then all organic fractions are combined, dried over anhydrous magnesium sulfate and concentrated in vacuo. The resulting material is purified by column chromatography on silica gel (hexane/ethyl acetate 3:1 ratio) to afford 4-(4′-chloro-4-ethyl-2′-fluorobiphenyl-3-yl)-2,2,6,6-tetramethyl-pyran-3,5-dione (0.248 g) as a white solid.
