Sodium hydride → 2,2,2-Trifluoro-1-(4-fluorophenyl)ethyl trifluoromethanesulfonate

A dried 50 mL of flask was charged sodium hydride, 60% dispersion in mineral oil (624 mg, 15.6 mmol) under N2 and then washed with dried hexane (20 mL) twice. Dried ethyl ether (10 mL) was added and a solution of 2,2,2-trifluoro-1(RS)-(4-fluorophenyl)ethanol (90% ee) (2.5 g, 12.89 mmol) in ethyl ether (10 mL) was added at 0° C. After completion of addition, the reaction mixture was allowed to warm up to room temperature and stirred for 1 h. A solution of trifluoromethanesulfonyl chloride (3.28 g, 19.5 mmol) in ethyl ether (10 mL) was added at 0° C. After completion of addition, the reaction was allowed to warm up to room temperature and stirred for 1 h. The solvent was removed under rot-vap and diluted with hexane (150 mL) and washed with a saturated NaHCO3 n and brine. After drying with MgSO4, the organic solvent was removed to give trifluor-methanesulfonic acid 2,2,2-trifluoro-1(RS)-(4-fluorophenyl)ethyl ester (3.15 g) (90% ee) as a colorless oil which was used in the next step without further purification.