General procedure: 3,3'-dimethylbiphenyl, 2-bromo-5-fluorotoluene, 2-bromotoluene and 2,4-dibromotoluene were synthesized using the following general procedure: boron trifluoride (TFB) was pre-synthesized prior to use according to the literature methods [7-9]. The corresponding aromatics (4 mmol) were dissolved in Freon R 113 (4.1 mL) and the solution was cooled to -25 °C. The corresponding TFB (2 mmol) was slowly added to the aromatic solution under vigorous stirring, followed by removal of the cooling bath. The reaction mixture was stirred at 45 °C for 5 hours. Upon completion of the reaction, the reaction mixture was treated with H2O and filtered to remove the metal fluoride precipitate. Subsequently, the liquid phase was treated with 10% NaNO2 aqueous solution to remove traces of bromine and 30% CaCl2 aqueous solution to remove F- anions. Finally, Freon R 113 was removed from the organic phase by evaporation and the resulting product was purified by rapid chromatography on silica gel, the eluent being a hexane:EtOAc solvent mixture.
