Step 1: Synthesis of 1-bromo-4,5-difluoro-2-methylbenzene (16). Bromine (Br2) (40 g, 250 mmol) was added slowly and dropwise to a reaction flask containing 3,4-difluorotoluene (15) (27 g, 210 mmol) and iron powder (600 mg, 10 mmol) under ice bath conditions. The reaction mixture was slowly warmed to room temperature with stirring and the reaction was continued for 12 hours. Upon completion of the reaction, the reaction was quenched by the addition of water and the mixture was extracted with ether. The combined organic layers were washed sequentially with sodium thiosulfate solution and saturated brine and dried over anhydrous sodium sulfate (Na2SO4). The ether was removed by concentration under reduced pressure to give the target product 1-bromo-4,5-difluoro-2-methylbenzene (16) (36 g, 83% yield). 1H NMR (400 MHz, DMSO-d6): δ 7.78 (t, 1H), 7.52 (t, 1H), 2.29 (s, 3H).
