S(VI) Lewis acids: fluorosulfoxonium cations

Avenues to S-based Lewis acids were developed via the oxidation of aryl-sulfoxides with XeF2, giving difluorodiarylsulfoxides which react via fluoride abstraction to afford Lewis acidic fluorosulfoxonium cations; this acidity is derived from the S–F σ* orbital and has been probed both experimentally and computationally.