The dimethylsulfonium moiety as a leaving group in aromatic radiofluorination using tetra-n-butylammonium [18F]fluoride

The reaction of aryldimethylsulfonium methylsulfates with tetra-n-butylammonium [18F]fluoride in acetonitrile or dimethyl sulfoxide has been studied. Fluorine-18 incorporation into the aromatic ring of the selected aryldimethylsulfonium salts was observed, depending greatly on the substituent group on the aromatic ring. It was found that the displacement yields with the p-nitro- and o-nitro-substituted substrates are consistently greater using a polymethylpentene vessel than those using a Pyrex vessel. The nucleophilic displacement of the dimethylsulfonium group was not a good general method for labeling aromatic compounds with 18F, because of the facile demethylation of the sulfonium salt by a nucleophile present. (author)