1. Fluorene (5.00 g, 30.08 mmol) was dissolved in 40 mL of chloroform. A solution of bromine (3.08 mL) dissolved in 15 mL of chloroform was slowly added dropwise at 0°C and protected from light, and the reaction was stirred for 10 hours. After completion of the reaction, the mixture was quenched by pouring it into aqueous Na2S2O3. Extracted with dichloromethane (15 mL x 3), the organic layers were combined and washed sequentially with deionized water (25 mL x 3) and saturated brine (20 mL). The organic layer was dried over anhydrous magnesium sulfate and the solvent was removed by rotary evaporation. The crude product was recrystallized with anhydrous ethanol to afford 2,7-dibromofluorene as a white solid (7.04 g, 72.2% yield).
2. 2,7-Dibromofluorene (6.40 g, 19.75 mmol), tetrabutylammonium bromide (0.10 g, 0.31 mmol) and 1-bromododecane (10 mL, 41.65 mmol) were dissolved in a mixed solvent of 60 mL of toluene and 25 mL of 50 wt% NaOH aqueous solution, and the reaction was carried out at reflux at 80 °C for 24 h under argon protection. At the end of the reaction, it was extracted with ethyl acetate (25 mL×3), and the organic layers were combined and washed with deionized water (25 mL×3) and saturated brine (30 mL) sequentially. The organic layer was dried over anhydrous magnesium sulfate and the solvent was removed by rotary evaporation. The crude product was separated by column chromatography (petroleum ether:dichloromethane=4:1) to afford 2,7-dibromo-9,9-bisdodecylfluorene (11.30 g, 86.6% yield) as a pale yellow solid.
3. 2,7-Dibromo-9,9-didodecylfluorene (2.00 g, 3.03 mmol) was dissolved in 60 mL of dichloromethane, 10 mL of concentrated sulfuric acid was added, and after cooling, ceric ammonium nitrate (4.98 g, 9.08 mmol) was added in batches, and the reaction was stirred for 1 hour. After the reaction was completed, it was quenched by adding 50 mL of deionized water and extracted with dichloromethane (15 mL x 3). The organic layers were combined and washed sequentially with deionized water (25 mL × 3) and saturated brine (20 mL). The organic layers were dried over anhydrous magnesium sulfate and the solvent was removed by rotary evaporation. The crude product was separated by column chromatography (petroleum ether:dichloromethane=4:1) to afford the orange-yellow product 2,7-dibromo-9,9-bisdodecyl-1,6-difuran (1.7 g, 74.56% yield).
