The general procedure for the synthesis of 3,4,5-trifluoroiodobenzene from 3,4,5-trifluorobromobenzene was as follows: first, magnesium (5.76 g, 237 mmol) and iodine (10.0 mg, 40.0 μmol) were added to tetrahydrofuran (190 mL), followed by the slow dropwise addition of 3,4,5-trifluorobromobenzene (50.0 g, 237 mmol). The reaction mixture was stirred at room temperature for 30 min. Next, a tetrahydrofuran solution (160 mL) of iodine (66.1 g, 261 mmol) was added at 0 °C and the mixture was continued to be stirred at room temperature for 2 hours. Upon completion of the reaction, the mixture was poured into ice water, neutralized with concentrated hydrochloric acid and then extracted with hexane. The extract was sequentially washed with saturated aqueous sodium thiosulfate and dried over anhydrous sodium sulfate, followed by concentration under reduced pressure. Finally, the concentrate was purified by silica gel column chromatography (eluent: ethyl acetate/hexane=1/10) to afford the title compound 3,4,5-trifluoroiodobenzene as a yellow oil (yield 45.0 g, 70%).1H NMR (CDCl3) δ: 7.32 (2H, t, J=6.4 Hz).
