General procedure for the synthesis of 4-bromo-2-iodo-1-(trifluoromethyl)benzene from 5-bromo-2-(trifluoromethyl)aniline: to a stirred solution of anhydrous THF (10 mL) with 5-bromo-2-(trifluoromethyl)aniline (300 mg, 1.255 mmol) was added at -78 °C the BF3-ether compound (707 mg, 5.02 mmol) and tertiary nitrite butyl ester (452 mg, 4.39 mmol). The reaction mixture was stirred for 10 min, slowly warmed to room temperature and continued stirring for 30 min. Upon completion of the reaction, the reaction mixture was diluted with ether (30 mL), the solid was collected by filtration and dried under vacuum. The resulting diazonium salt was added to an acetone solution containing KI (289 mg, 1.746 mmol) and iodine (203 mg, 0.876 mmol), which was pre-positioned in another flask at 0 °C. The reaction mixture was stirred at 0 °C for 1 h and then concentrated under reduced pressure. The residue was diluted with water (20 mL) and the product was extracted with ether (2 x 20 mL). The combined organic layers were dried over anhydrous sodium sulfate and concentrated under reduced pressure to afford 4-bromo-2-iodo-1-(trifluoromethyl)benzene (230 mg, yield not specified). The product was characterized by 1H NMR (400 MHz, CDCl3): δ 8.19 (s, 1H), 7.59 (d, 1H), 7.50 (d, 1H).
