General procedure for the synthesis of 1,5-difluoro-2-iodo-4-toluene from 2,4-difluorotoluene: To a solution of 2,4-difluoro-1-methylbenzene (6 g, 47 mmol) in trifluoroacetic acid (15 mL) was added N-iodosuccinimide (12.1 g, 53.7 mmol). The reaction mixture was stirred at room temperature overnight. Upon completion of the reaction, the mixture was poured into ice water and extracted with hexane (3 x 20 mL). The organic layers were combined and washed sequentially with saturated sodium thiosulfate solution, saturated sodium bicarbonate solution and brine, and then dried with anhydrous magnesium sulfate. After filtration, the filtrate was concentrated under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate=10:1) to afford 1,5-difluoro-2-iodo-4-toluene (10.7 g, 90% yield) as a colorless oil.1H NMR (400 MHz, CDCl3) δppm: 2.15-2.30 (m, 3H, CH3), 6.73-6.85 (m, 1H ArH), 7.55 (t, J=7.69Hz, 1H, ArH).
