Copper-Mediated Deoxygenative Trifluoromethylation of Benzylic Xanthates: Generation of a C-CF3 Bond from an O-Based Electrophile

The conversion of an alcohol-based functional group, into a trifluoromethyl analogue is a desirable transformation. However, few methods are capable of converting O-based electrophiles into trifluoromethanes. The copper-mediated trifluoromethylation of benzylic xanthates using Umemoto's reagent as the source of CF3 to form CCF3 bonds is described. The method is compatible with an array of benzylic xanthates bearing useful functional groups. A preliminary mechanistic investigation suggests that the CCF3 bond forms by reaction of the substrate with in situ generated CuCF3 and CuOTf. Further evidence suggests that the reaction could proceed via a radical cation intermediate.