Decarboxylative Allylation of Trifluoroethyl Sulfones and Approach to Difluoromethyl Compounds

Allyl carbonates undergo palladium-catalyzed decarboxylative allylation of trifluoroethyl phenyl sulfones. The success of the allylation, which is not efficient under typical strong base-mediated conditions, is the result of mild conditions thanks to a progressive delivery of ethoxide. Indeed, ethyl allyl carbonates act as a latent source of ethoxide for generation of the trifluoroethyl carbanion that reacts with the π-allylpalladium complex. The utility of the method is illustrated in a new approach to difluoromethyl compounds.