Copper-Catalyzed 1,2-Bistrifluoromethylation of Terminal Alkenes

Many efficient catalytic methods for the introduction of trifluoromethyl group (CF ₃ ) have been reported. Among them, the addition of CF ₃ and other components to alkenes is well known, and many components such as azides, cyanides, amines, and halides have been inserted into alkenes with CF ₃ . However, to date the double catalytic insertion of CF ₃ into an alkene is unknown. Herein, we report the catalytic 1,2-bistrifluoromethylations of alkenes catalyzed by Copper (Cu). We used two CF ₃ sources, namely Umemoto's reagent and (trifluoromethyl)trimethylsilane (TMSCF ₃ ). Each reagent plays a unique role during this transformation; Umemoto's reagent generates CF ₃ radicals, while TMSCF ₃ is used to form CF ₃ anions. Copper (I) bromide (CuBr) exhibited the best catalytic activity for this reaction. We believe that CuBr oxidizes the alkyl radical, which is produced by the addition of the CF ₃ radical to the alkene, to the corresponding alkyl cation, which then reacts with the CF ₃ anion from TMSCF ₃ to produce the desired product. This reaction tolerates a diverse set of substrates bearing functional groups such as amides, esters, ethers, ketones, protected amines, tertiary amines, and phthalimides; hence this transformation is widely applicable to a wide variety of substrates. (Figure presented.).