This work focuses on the development of new synthetic methods for the preparation of various N-heterocycles. While I have encountered many road blocks throughout my PhD, it has taught me how to solve a wide variety of challenges through perseverance, critical thinking and collaboration. I have successfully developed multiple projects stemming from my independent ideas for new chemical transformations. The projects range from cyclizations of o-alkenylisocyanides using a variety of radical precursors to C(sp3)-H amination (with and without transition metals) reactions. The discovery of selective addition of radicals to isonitriles could be harnessed to initiate a radical cascade that was designed to overcome the stereoelectronic restrictions on homoallylic ring expansion in alkyne reactions by using alkenes as synthetic equivalents of alkynes. This allowed us to establish a new route for N-heteroaromatics by coupling a homoallylic ring expansion with a stereoelectronically assisted C-C bond scission to yield the formal “6-endo” products. Additionally we have developed multiple protocols for C(sp3)-H aminations. Firstly, a transition metal mediated approach using FeCl3/DDQ for an intramolecular C(sp3)-H oxidative amination. In this reaction, an aniline group can activate the molecule for single-electron-transfer while also acting as an internal nucleophile to trap reactive intermediates. Following a consecutive electron transfer oxidation process, we can couple free amines with -CH2- groups to afford aromatic N-heterocycles using inexpensive reagents. Expansion of the intramolecular oxidative C(sp3)-H amination to unprotected anilines and amides and C(sp3)-H bonds to occur under mild conditions using t-BuOK, DMF and O2. This protocol relies on a synergy between base, radical and oxidizing species to promote a coordinated sequence of deprotonation followed by H-atom transfer and oxidation that constructs a new C-N bond. We were able to apply this chemistry to the preparation of a wide variety of N-heterocycles, ranging from small molecules to extended aromatics without the need for transition metals or strong oxidants. / A Dissertation submitted to the Department of Chemistry and Biochemistry in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester 2018. / April 13, 2018. / Development, Methodology, N-heterocycles, Organic, Reaction / Includes bibliographical references. / Igor V. Alabugin, Professor Directing Dissertation; Michael Blaber, University Representative; Kenneth Hanson, Committee Member; Justin Kennemur, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_653411 |
| Contributors | Evoniuk, Christopher J. (Christopher Jordan) (author), Alabugin, Igor V. (professor directing dissertation), Blaber, Michael (university representative), Hanson, Kenneth G. (committee member), Kennemur, Justin Glenn (committee member), Florida State University (degree granting institution), College of Arts and Sciences (degree granting college), Department of Chemistry and Biochemistry (degree granting departmentdgg) |
| Publisher | Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text, doctoral thesis |
| Format | 1 online resource (287 pages), computer, application/pdf |
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