Boron trifluoride etherate → Tert-butyl 5,5,5-trifluoropentanoate

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of 5,5,5-trifluoropentanoic acid (5 g, 32.0 mmol) in THF (30 mL) and hexane (30 mL) at 0° C., was added tert-butyl 2,2,2-trichloroacetimidate (11.46 mL, 64.1 mmol). The mixture was stirred for 15 min at 0° C. Boron trifluoride etherate (0.406 mL, 3.20 mmol) was added and the reaction mixture was allowed to warm to room temperature overnight. To the clear reaction mixture was added solid NaHCO3 (5 g) and stirred for 30 min. The mixture was filtered through MgSO4 and washed with hexanes (200 mL). The solution was allowed to rest for 45 min, and the resulting solid material was removed by filtering on the same MgSO4 filter again, washed with hexanes (100 mL) and concentrated under reduced pressure without heat. The volume was reduced to about 30 mL, filtered through a clean fritted funnel, washed with hexane (5 mL), and then concentrated under reduced pressure without heat. The resulting neat oil was filtered through a 0.45 μm nylon membrane filter disk to provide tert-butyl 5,5,5-trifluoropentanoate (6.6 g, 31.4 mmol 98% yield) as a colorless oil: 1H NMR (400 MHz, CDCl3) δ ppm 1.38 (s, 9H) 1.74-1.83 (m, 2H) 2.00-2.13 (m, 2H) 2.24 (t, J=7.28 Hz, 2H).

Provenance & Evidence