The Development of Complexity Generating Organic Photoredox Transformations and the Application of These Transformations in Complex Molecule Synthesis

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  • March 19, 2019
Creator
  • Gesmundo, Nathan
    • Affiliation: College of Arts and Sciences, Department of Chemistry
Abstract
  • Described herein are three methods for the direct functionalization of alkenes, enabled by organic photoredox catalysis. Additionally, a model system studying the application of a photoredox cyclization method in natural product synthesis is described. I. Introduction to Visible Light Photoredox Catalysis An overview of visible light photoredox catalysis is presented. The principles of photoredox catalysis and single electron transfer are discussed and excited state photooxidants are introduced. II. Cyclization-Endoperoxidation Cascade of Unconjugated Dienes Mediated by a Pyrylium Photoredox Catalyst A method for the direct synthesis of bicyclic endoperoxides from unconjugated dienes using a pyrylium photoredox catalyst is presented. The reaction proceeds through the intermediacy of a distonic cation radical, with molecular oxygen serving as the peroxide source. Emphasis of this chapter is on the complimentary nature of our endoperoxidation strategy. III. Development of a Method to Directly Access γ-Lactam and Pyrrolidine Heterocycles via Polar Radical Crossover Cyclizations A method for the direct synthesis of γ-lactam and pyrrolidine heterocycles from alkenes and unsaturated N-nucleophiles is described. The reaction proceeds via a cation radical intermediate and utilizes a dual catalytic system comprised of an acridinium photooxidant and a redox active hydrogen atom donor to produce the heterocyclic products. The boundaries of this mode of reactivity are explored and the complimentary nature of this method is emphasized. IV. Application of a Cation Radical Mediated Polar Radical Crossover Cycylization in a Rubriflordilactone B Model System A model system to explore the possibility of rubriflordilactone B synthesis utilizing a polar radical crossover cyclization as the key step is designed. Work on a key Mukaiyama vinylogous aldol reaction is presented as well as exploratory work on the central tetrahydrofuran-forming cyclization. Discussions of related syntheses, retrosynthetic analysis, and future work are also presented. V. Hydrotrifluoromethylation of Aliphatic Alkenes and Styrenes A method for the catalytic hydrotrifluoromethylation of alkenes using an organic photoredox system is disclosed. The strategy operates by single electron oxidation of sodium trifluoromethane sulfinate and is tolerant of aliphatic and styrenyl alkene substrates. A dual catalytic system of an acridinium photoredox catalyst and a redox-active hydrogen atom donor is used to generate the observed products.
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  • In Copyright
Advisor
  • Johnson, Jeffrey
  • You, Wei
  • Nicewicz, David
  • Alexanian, Erik
  • Templeton, Joseph
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2015
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  • Chapel Hill, NC
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  • There are no restrictions to this item.
Date uploaded
  • June 23, 2015

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