A dry 500-mL three-neck flask was flushed with N2 and was charged with 8-(2-ethylhexoxy)-4-(2-ethylhexyl)thieno[2,3-f]benzothiophene (8.4 g, 0.020 mol) and THF (200 mL, 0.1 M) via deoxygenated syringe. The reaction flask was cooled to −78° C. and a 2.0 M solution of n-butyllithium in hexanes (10 mL, 0.020 mol) was added dropwise via deoxygenated syringe. After 30 minutes of stirring at −78° C., dibromotetrafluoroethane (7.8 g, 0.030 mol) was added to the reaction flask and stirring continued for 1 hour at −78° C. The cooling bath was removed and the reaction mixture was allowed to warm up to ambient temperature. As the reaction was completed, cool DI water (50 mL) was slowly added to the reaction flask. Then, the reaction mixture was poured into 150 mL of cool water and extracted with hexanes (200 mL) three times. The combined organic layer was dried over anhydrous magnesium sulfate (MgSO4). After the product was filtered, the solvent was removed by rotary evaporation. The product was purified using column chromatography on silica gel with hexanes/chloroform (gradient) to yield colorless oil (4.2 g, 42%).
