Date on Master's Thesis/Doctoral Dissertation
Committee Co-Chair (if applicable)
Nigeria; Louisville; hydrogen bond basicity; Obafemi Awolowo University
The utility of fluorine in medicinal and manufacturing chemistry is undisputed. Despite its usefulness, the incorporation of fluorine in organic molecules is not without challenges. Regardless of their electrophilic or nucleophilic nature, most, if not all, fluorinating reagents derive from HF. Nucleophilic reagents are less expensive compared with their counterparts, and many are not commercially available. The Hammond laboratory is interested in developing and applying HF-based fluorination reagents that are cost effective and capable of enhancing both classical and metal based transformations. The following chapters describe some of the applications of our HF-based reagent. Chapter 2 discusses the preparation and role of DMPU-HF in the fluorination of alkynes in the presence of a metal catalyst. This reaction employs the imidogold precatalyst, which is activated by DMPU-HF to enhance both mono- and di-fluorination of alkynes. Approaches to induce monofluorination and difluorination of terminal alkynes by an HF-based reagent, unprecedented in the literature, are also discussed. In Chapter 3, we describe further the application of DMPU-HF to the diastereoselective synthesis of fluorinated tetrahydropyrans and the N-tosylpiperidine analogues. We also showed that the acidic behavior of DMPU-HF makes it a better fluorinating reagent when compared to existing HF-based reagents in these types of transformations. Further extension of DMPU-HF to the ring opening of aziridines is discussed in Chapter 4. A wide variety of N-tosyl aziridines undergo efficient ring opening in the presence of DMPU-HF at room temperature. The methodology was also extended to some N-substituted aziridines including unactivated substrates, all of which were efficiently fluorinated under these conditions. Chapter 5 gives an overview of some of the applications of DMPU-HF to other known C-F bond formations. Examples of such transformations include but are not limited to the ring opening of epoxides, fluorobromination of unsaturated compounds and the metal free synthesis of fluoroamines. Finally, Chapter 6 provides spectroscopic data for all the new compounds prepared in chapters 2 to 5.
Okoromoba, Otome Elisha, "Development and applications of novel HF-based fluorination reagents : DMPU-HF." (2016). Electronic Theses and Dissertations. Paper 2393.