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The general procedure for the synthesis of 2,7-dibromo-9,9-difluoro-9H-fluorene from 2,7-dibromo-9-fluorenone is as follows: 2,7-dibromo-9-fluorenone (4.0 g, 11.8 mmol) was suspended in deoxyfluoric acid (12 mL) at room temperature and ethanol (4 drops) was added. The stirred suspension was heated at 90 °C for 24 h. (Note: when using deoxyfluor at high temperatures, a rapid and violent exothermic reaction may occur). When the reaction is complete, the mixture is cooled to room temperature and poured onto ice containing sodium bicarbonate. The solid formed is collected by filtration. The crude product was dissolved in ethyl acetate and washed sequentially with 1 M aqueous hydrochloric acid and brine. The organic phase was dried with anhydrous sodium sulfate, filtered and the solvent evaporated to give the crude product. The crude product was purified by silica gel column chromatography (eluent: ethyl acetate/hexane) to afford the target product 2,7-dibromo-9,9-difluoro-9H-fluorene (3.2 g).19F-NMR (282 MHz, dmso-d6) δ: -111.6 ppm.The solution of the product in ethyl acetate was passed through activated charcoal prior to the next step in the use.

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