1-(Trifluoroacetyl)piperidine

Typical Procedure:
4-Bromotoluene (9.45 g, 55.25 mmol) is dissolved in Et₂O (280 mL) and cooled to -40 °C. n-Butyllithium (1.1 M in hexane, 40.5 mL, 60.74 mmol) is added dropwise, and the solution is warmed to 0 °C over a 2 h period. The solution is then cooled to -60 °C and a solution of 1-(trifluoroacetyl)piperidine (10.00 g 55.23 mmol) in dry Et₂O (60 mL) is added in portions. The reaction is allowed to stir at -60 °C for 3 h and then warmed to room temperature. The solution is hydrolyzed with saturated NH₄Cl (50 mL) and washed with NH₄Cl (5 x 50 mL) and H₂O (3 x 50 mL). The organic phase is dried over MgSO₄, and the solvent is removed in vacuo. The remaining oil is purified by flash column chromatography eluting with hexane/CH₂Cl₂ (5:1, 4:1, and 3:1) to give a colorless oil (5.62 g, 54%).