[Synthesis]
To a stirred solution of trifluoroethanol (10 g, 0.06 mol) in anhydrous dichloromethane (CH2Cl2, 100 mL) was added N,N-diisopropylethylamine (DIPEA; 29 mL, 0.16 mol) at room temperature and the reaction mixture was cooled to -78°C. At -78°C, trifluoromethanesulfonic anhydride (13.5 mL, 0.07 mol) to the reaction mixture. After stirring for 30 minutes, the reaction mixture was slowly warmed to -30°C and stirring was continued for 30 minutes. Upon completion of the reaction, the reaction was quenched with deionized water (200 mL) and extracted with dichloromethane (CH2Cl2, 2 x 300 mL). The organic layers were combined, washed sequentially with 1N hydrochloric acid (HCl) and deionized water, dried over anhydrous sodium sulfate (Na2SO4) and filtered. To a stirred N,N-dimethylformamide (DMF, 100 mL) solution of 4-bromophenol (4 g, 0.02 mol) and cesium carbonate (Cs2CO3; 15 g, 0.04 mol) was added the dichloromethane layer after the above treatment at room temperature. The mixture was stirred for 16 hours, during which time the progress of the reaction was monitored by thin layer chromatography (TLC). Upon completion of the reaction, the reaction mixture was diluted with deionized water and extracted with dichloromethane (CH2Cl2, 2 x 250 mL). The organic layers were combined, dried over anhydrous sodium sulfate (Na2SO4), filtered and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (SiO2, 60-120 mesh) to afford the target compound 1-bromo-4-(1,1,2,2,2-pentafluoroethoxy)benzene (3.5 g, 11.5 mmol, 50% yield) as a colorless liquid.1H NMR (200 MHz, CDCl3): δ 7.46-7.38 (m, 2H), 6.87- 6.79 (m, 2H), 4.45-4.32 (m, 2H). |