No carrier-added nucleophilic aromatic radiofluorination using solid phase supported arenediazonium sulfonates and 1-(aryldiazenyl)piperazines

This Letter concerns the investigation of a solid phase based method for no carrier-added nucleophilic [18F]fluorination of aromatic compounds via de-diazofluorination. Initial screening of reaction conditions was conducted using soluble analogues, that is, substituted benzenediazonium tosylates and 1-(phenyldiazenyl)piperazines in solution. This was followed by translation of the principle conditions to solid phase bound analogues. A variety of substituted aryldiazonium cations were immobilised using a sulfonate functionalised ion exchange resin and labelled with [18F]fluoride ion by Balz–Schiemann like thermal decomposition in the presence of no carrier-added [18F]fluoride ion. Likewise, a chloromethyl-bearing (Merrifield-) resin was modified using piperazine to provide the means for covalent immobilisation of diazonium ions. The resin bound 1-(aryldiazenyl)piperazines obtained were used as substrates for a Wallach reaction with hydrogen [18F]fluoride.