Synthesis of [18F]F-DOPA using hypervalent iodine compounds

• Main Author: Edwards, Richard
• Published: Cardiff University 2015
• Subjects: 547; QD Chemistry
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678969

[18F]F-DOPA is a widely used radiotracer most commonly employed in the diagnosis of Parkinson’s disease[1] and neuroendocrine tumours (NETs).[2] In this thesis, the syntheses of suitable diaryliodonium salt precursors for [18F]F-DOPA production via fluorination with nucleophilic, no carrier added (n.c.a.) [18F]fluoride are described. The complex iodonium salt precursors are prepared by a simple and robust procedure in good yields and are bench stable compounds. Incorporation of both ‘cold’ [19F]fluoride and ‘hot’ [18F]fluoride using the prepared precursors has been investigated.[3] Fluorinations occur with complete regioselectivity for fluorination at the DOPA moiety when using a range of precursors with varying protecting group strategies. Optimisation of the radiofluorination and subsequent isolation method allowed for isolation of a protected [18F]F-DOPA species in 2% radiochemical yield (RCY). Solid-Supported Iodonium Salts for Fluorinations (CH3) Secondly, solid-supported iodonium salt precursors have been prepared and used for the production of fluoroarenes. The importance of the resin functionality for the attachment of the iodonium salt moieties has been demonstrated. Use of a tris(aminoethyl) funtionalised resin rather than aminomethyl resin as starting material gives improved reproducibility and yields for precursor formation. The successful radiofluorination of a simple solid-supported precursor with no carrier added (n.c.a) [18F]fluoride is also reported, producing [18F]fluorobenzene with 3% radiochemical conversion (RCC).[4] Extension of the solid-supported methodology to the production of synthetically useful fluoroarenes was investigated. Preparation of benzyl protected 4-fluorophenol was accomplished using this strategy. Optimisation of the fluorination conditions gave 24% yield of the aryl fluoride from the resin bound iodonium salt precursor.