Fluorinated Dialkyl Chloronium Salts: Synthesis and Reactivity for Fluoroalkylation and Hydride Abstraction

A new concept for the synthesis of dialkyl chloronium cations [R−Cl−R] + is described (R=CH 3 , CH 2 CF 3 ), that allows the formation of fluorinated derivatives. By utilizing the xenonium salt [XeOTeF 5 ][M(OTeF 5 ) n ] (M=Sb, n =6; M=Al, n =4) chlorine atoms of chloroalkanes or the deactivated chlorofluoroalkane CH 2 ClCF 3 are oxidized and removed as ClOTeF 5 leading to the isolation of the corresponding chloronium salt. Since the resulting highly electrophilic cation [Cl(CH 2 CF 3 ) 2 ] + is able to alkylate weak nucleophiles, this compound can be utilized for the introduction of a fluorinated alkyl group to those. In addition, the fluorinated alkyl chloronium cation displays a high hydride ion affinity, enabling the activation of linear hydrocarbons by hydride abstraction even at low temperatures ultimately leading to the formation of branched carbocations.