This thesis concerns method development of new synthetic routes by applying electrophilic hypervalent iodine reagents, such as trifluoromethyl-benziodoxole (Togni reagent) and fluoro-benziodoxole. The first project involved the addition of an oxygen moiety and trifluoromethyl group across double and triple bonds (both groups derived from the hypervalent iodine reagent). We observed that electron donating substituents on the aromatic ring of the substrate accelerated the oxytrifluoromethylation reaction. This transformation was further expanded to halo-trifluoromethylation reaction of a vinyl silane substrate. We also developed a copper mediated cyanotrifluoromethylation reaction, which was accelerated by PCy₃ additive. This transformation allowed for the creation of two new C-C bonds in a single addition reaction. The direct C-H trifluoromethylation reaction of quinones was achived using the Togni-reagent in the presence of B₂pin₂ additive. The intriguing additive effects of both B₂pin₂ and PCy₃ inspired us to examine the mechanism of these transformations.

Fluoro-benziodoxole is the fluoroiodane analogue of the trifluoromethylating Togni reagent. We developed a AgBF₄ mediated geminal difluorination of styrenes using this fluoroiodine reagent. In this process one fluorine atom came from the fluoroiodane, while the other fluorine was derived from the tetrafluoroborate ion. A similar approach was applied for the 1,3-oxyfluorination and difluorination of cyclopropanes. Similarly, this fluorinative ring opening of unactivated cyclopropanes involved the introduction of an electrophilic fluorine atom from the fluoroiodane reagent and a nucleophilic one from the tetrafluoroborate ion. This reaction was extended to synthesis of 1,3-oxyfluorinated products. When alkenes reacted with the fluoro-benziodoxole reagent in the presence of palladium catalyst the iodofluorination reaction occurred.  Both the iodine and fluorine atoms were derived from the fluoroiodane reagent. The iodofluorination reaction with disubstituted and cyclic alkenes proceeded with high regio- and stereoselectivity.

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.