| 总结: | <p><strong>Chapter 1</strong> (<em>Introduction</em>) summarises the key concepts surrounding Positron Emission Tomography (PET) imaging, including the underlying physical principles and its applications and the use of fluorine-18 as a PET radioisotope. A brief account of fluorine-18 radiochemistry, including the 18F-fluorination of aliphatic and aromatic scaffolds, as well as 18F-fluoroalkylation chemistry is also provided. The chapter concludes with an outline of the work disclosed in this thesis.</p>
<p><strong>Chapter 2</strong> (<em>18F-Difluoromethylation with [18F]Difluorocarbene</em>) begins with an account of the properties of difluoromethylated molecules and the methods employed to access them in non-radiolabelled and radiolabelled form. [18F]Difluorocarbene is next introduced as a new reactive intermediate for 18F-radiochemistry. Three key advances in this area are disclosed. Firstly, the development of a new-generation [18F]difluorocarbene reagent with improved properties is described, followed by the first application of this chemistry to PET imaging. Finally, a novel Pd-mediated 18F-difluoromethylation of aryl boronic acids is disclosed.</p>
<p><strong>Chapter 3</strong> (<em>Deaminative 18F-Fluorination of Heteroaryl Pyridinium Salts</em>) first provides an overview of SNAr reactivity with both 19F-fluoride and [18F]fluoride, followed by a summary of the synthesis of pyridinium salts, as well as their reactivity. The development of a pyridinium-based 18F-fluorodeamination of heteroaryl amines is then disclosed. Attention is then given to the automation and scale-up of the reaction, the use of pyridinium salts as elution reagents, the evaluation of crude pyridinium salts in 18F-fluorination and comparison to other substrates.</p>
<p><strong>Chapter 4</strong> (<em>Experimental</em>) contains experimental details for the work disclosed in Chapters 2 and 3, including procedures and characterisation for synthesised compounds, as well as radiosynthesis procedures and data.</p>
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