Development of new Fluorination Methods Directed to Fluorine-18 Labelling
Abstract: This thesis deals with the development of new fluorination reactions and their application to fluorine-18 labelling. Fluorine-18 labelled compounds are employed as tracers in Positron Emission Tomography (PET), which is a powerful non-invasive imaging method in medical diagnostics.The first part of this thesis focuses on the development of a late-stage halogen exchange-based fluorination method for the synthesis of trifluoromethylated molecules. The first project in this area relies on the application of a copper(I)-based fluorinating reagent to furnish trifluoroacetates, trifluorotoluenes and trifluoroacetamides. The second project involves the translation of this methodology into the fluorine-18 labelling of tertiary and secondary trifluoroacetamides. The targeted substrates were labelled in high radiochemical yield and high molar activity using [18F]Bu4NF as fluorine source in the presence of an organic activator.In the second part, the development of electrophilic fluorination reactions using a hypervalent iodine-based reagent is discussed. The first project in this area addresses the development of an electrophilic fluorine-18 fluorination reagent: [18F]fluoro-benziodoxole. The utility of this reagent was demonstrated in the labelling of [18F]fluoro-benzoxazepines. In the second project, the same [18F]fluoro-benziodoxole reagent was used in the rhodium-mediated synthesis of α-[18F]fluoroethers. High molar activities were obtained in these electrophilic labelling processes. In the third project, the fluorine-19 analog fluoro-benziodoxole was used in the palladium-catalyzed iodofluorination of allyl benzenes, styrenes and cycloalkenes. Both iodine and fluorine atoms in the product arise from the same reagent.
CLICK HERE TO DOWNLOAD THE WHOLE DISSERTATION. (in PDF format)