Enantioselective alkene difunctionalization enabled by organochalcogen catalysis I. Lewis base-catalyzed sulfenium ion transfer II. Organoselenium redox catalysis
Panger, Jesse Lee
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https://hdl.handle.net/2142/120368
Description
Title
Enantioselective alkene difunctionalization enabled by organochalcogen catalysis I. Lewis base-catalyzed sulfenium ion transfer II. Organoselenium redox catalysis
Author(s)
Panger, Jesse Lee
Issue Date
2023-04-25
Director of Research (if dissertation) or Advisor (if thesis)
Denmark, Scott E
Doctoral Committee Chair(s)
Denmark, Scott E
Committee Member(s)
Sarlah, David
Girolami, Gregory S
Mirica, Liviu M
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
organocatalysis
chalcogen
enantioselective
sulfenofunctionalization
Lewis base catalysis
Abstract
The thesis herein will cover broadly the application of main group organoselenium catalysis for: (1) the enantioselective transfer of sulfenium ions to alkenes to form lactams, (2) the enantioselective transfer of sulfenium ions to specifically Z-alkenes and the physical organic differences in reactivity between E- and Z-alkenes, and (3) diselenide-catalyzed syn-difunctionalization of alkenes under an oxidative manifold. A further appendix will include work toward the activation and utilization of nitrenium ions for enantioselective aziridination which ultimately was not successful but has important foundational work conducted.
Chapter 1 will cover the background of Lewis base catalysis and its application in organic synthesis. Then it will transition into enantioselective sulfenium ion transfer and how the Denmark laboratory has found success with different nucleophiles to afford attractive sulfenofunctionalized products (Chapter 2). These products can be rapidly diversified into a wide variety of useful products under operationally simple transformations. Chapter 3 will expand on the previous discussion by showcasing examples where earlier methodology overlooked critical insights into the catalyst/alkene combination. These studies include both a physical organic look at the mechanism as well as the synthetic applicability. Chapter 4 will change focus to organoselenium redox catalysis whereby a highly electrophilic selenium species becomes susceptible to displacement by careful choice of nucleophile. The selenium species undergoes two displacements to render the whole process catalytic in selenium, a stark contrast to the sulfenofunctionalization discussed in chapters 1-3. The key finding of the addition of fluoride scavengers has the effect of enhancing reactivity in some cases, and in other cases fully ‘turning on’ reactivity. Using a fluoride scavenger has opened up the platform for what is possible under the reaction manifold utilized in these laboratories.
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