Cooperative Lewis acidity in borane-substituted fluorophosphonium cations

A series of aryl-difluorophosphoranes are converted to give fluorophosphonium salts [Ph2PF(o-C6X4BR2)]+ (X = H, F; R = Cy, Mes). The proximity of the two weakly Lewis acidic fluorophosphonium and borane moieties results in enhanced Lewis acid catalytic reactivity.