A New and Efficient Method for the Trifluoromethylation of Carbonyl Compounds with Trifluoromethyltrimethylsilane in DMSO

Abstract

In the presence of MS 4 Å in DMSO, trifluoromethyl­ation of various aldehydes and ketones with trifluoromethyltri­methylsilane (TMSCF₃) proceeded very smoothly to give the corresponding trifluoromethylated adduct in good to quantitative yields without a base catalyst.

trifluoromethylation - trifluoromethyltrimethylsilane - carbonyl compounds - DMSO

References and Notes

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Typical Procedure.
A solution of benzaldehyde (30 µL, 0.30 mmol) and TMSCF₃ (54 µL, 0.36 mmol) in DMSO (2 mL) in the presence of powdered MS 4 Å (150 mg) was stirred at r.t. under an argon atmosphere. After 15 min, the reaction mixture was quenched with a phosphate buffer (pH 7, 20 mL). The organic materials were extracted with Et₂O, dried over anhyd MgSO₄, and the solvent was evaporated in vacuo. ¹H NMR analysis (400 MHz) of the crude product using 1,1,2,2-tetrachloroethane as an internal standard shows that (2,2,2-trifluoro-1-phenylethoxy)trimethylsilane was obtained in quantitative yield. The product gave satisfactory ¹H NMR, ¹³C NMR, ¹⁹F NMR, and IR spectra after the purification by TLC on silica gel.

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