Enantioselective Copper-Catalyzed Intermolecular Cyano­trifluoro­methylation of Alkenes via Radical Process

A novel enantioselective copper-catalyzed
intermolecular cyano­trifluoro­methylation
of alkenes has been developed, in which a variety of CF3-containing alkylnitriles are furnished with excellent enantiomeric
excess. Preliminary mechanistic studies revealed (1) the reaction
was initiated by a SET process between activated Togni’s CF3+ reagent and a Cu­(I) catalyst; (2) the released
CF3 radical readily added to styrene to provide a benzylic
radical, which was then trapped by a chiral Cu­(II) cyanide species
to deliver the desired alkylnitriles; (3) a low concentration of the
CN anion was crucial to obtain high enantioselectivity.