A new method for the fluorine-18 labelling of trifluoromethyl ketones has been developed. This method is based on the conversion of a-COCF3 functional group to a difluoro enol silyl ether followed by halogenation and fluorine-18 labelling. The utility of this new method was demonstrated by the synthesis of fluorine-18 labelled neutrophil elastase inhibitors, which are potentially useful for detection of inflammatory disorders.

This work is focused on two areas: the chemistry of organofluorine and organoboron compounds. In the first chapter, a copper-catalysed synthesis of tri- and tetrasubstituted allenylboronic acids is presented. Extension of the same method leads to allenylboronic esters. The very reactive and moisture-sensitive allenylboronic acids are further applied to the reaction with aldehydes, ketones and imines to form homopropargyl alcohols and amines. In addition, an enantioselective reaction catalysed by a BINOL organocatalyst was developed to form tertiary alcohols with adjacent quaternary carbon stereocenters.

The second chapter specialises in the functionalisation of 2,2-difluoro enol silyl ethers with electrophilic reagents under mild reaction conditions. This allowed for the formation of perfluoroethyl ketones, 2-aryl-2,2-difluoro ketones as well as the novel -COCF₂SCF₃-moiety. 

The third chapter continues with electrophilic fluorination. A synthesis of an electrophilic, ¹⁸F-labelled hypervalent iodine reagent from nucleophilic ¹⁸F-labelled tetrabutylammonium fluoride was devised. Then, the ¹⁸F-labelling of o-styryl benzamides using the developed reagent afforded [¹⁸F]benzoxazepines in good radiochemical yields and molar activity.

The objective of the final chapter was the development of a method for the nucleophilic ¹⁸F-labelling of 2-halo-2,2-difluoro ketones derived from the corresponding 2,2-difluoro enol silyl ethers. The radiochemical utility of this method was demonstrated by fluorine-18 labelling of a potential neutrophil elastase ligand followed by successful preclinical studies.

This study reports a new application area of difluoro enol silyl ethers, which can be easily obtained from trifluoromethyl ketones. The main focus has been directed to the electrophilic fluoroalkylation and arylation methods. The trifluoromethylthiolation of difluoro enol silyl ethers can be used for the construction of a novel trifluoromethylthio-alpha, alpha-difluoroketone (-COCF2SCF3) functionality. The -CF2SCF3 moiety has interesting properties due to the electron-withdrawing, albeit lipophilic, character of the SCF3 group, which can be combined with the high electrophilicity of the difluoroketone motif. The methodology could also be extended to difluoro homologation of the trifluoromethyl ketones using the Togni reagent. In addition, we presented a method for transition-metal-free arylation of difluoro enol silyl ethers based on hypervalent iodines.

Tri- and tetrasubstituted allenylboronic acids were prepared via a new versatile copper-catalyzed methodology. The densely functionalized allenylboronic acids readily undergo propargylboration reactions with ketones and imines without any additives. Catalytic asymmetric propargylborylation of ketones is demonstrated with high stereoselectivity allowing for the synthesis of highly enantioenriched tertiary homopropargyl alcohols. The reaction is suitable for kinetic resolution of racemic allenylboronic acids affording alkynes with adjacent quaternary stereocenters.

Operationally simple radiosynthesis and purification of [F-18]fluoro-benziodoxole was developed starting from a cyclotron produced [F-18]F- precursor, [F-18]TBAF, and tosyl-benziodoxole. The synthetic utility of [F-18]fluoro-benziodoxole was demonstrated by electrophilic fluorocyclization of o-styrilamides proceeding with high RCC (typically 50-90%) and high molar activity (up to 396 GBq mol(-1)).