University of Illinois Urbana-Champaign

Selenium redox-catalyzed alkene syn-difunctionalization

Mumford, Emily Millicent

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https://hdl.handle.net/2142/121198

Description

Title
Selenium redox-catalyzed alkene syn-difunctionalization
Author(s)
Mumford, Emily Millicent
Issue Date
2023-06-08
Director of Research (if dissertation) or Advisor (if thesis)
Denmark, Scott E.
Doctoral Committee Chair(s)
Denmark, Scott E.
Committee Member(s)
  • van der Donk, Wilfred A.
  • Mirica, Liviu M.
  • Mehta, Angad P.
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
  • alkene
  • difunctionalization
  • main group redox catalysis
  • mechanism
  • oxazoline
  • imidazolidinone
  • selenium
Abstract
This thesis covers two projects both involving the use of selenium redox catalysis for alkene difunctionalization. It begins with a brief overview of the chemistry of electrophilic selenium reagents and their reactivity with alkenes to incorporate various nucleophiles in selenofunctionalization reactions. It then moves into examples where the incorporated selenide can be oxidized and displaced to give syn-dichlorination and syn-diamination products. In covering the state of the art in main group redox catalysis for alkene difunctionalization, comparisons are made to transformations accomplished using organoiodine redox catalysis. Chapter 2 covers the development of a high yielding and highly enantioselective alkene oxyamination reaction for the synthesis of 2-aryl oxazolines, based upon an existing strategy for alkene diamination. This oxyamination method uses N-tosyl benzamides in combination with alkene substrates, a chiral diselenide catalyst, and sym-collidinium fluoride tetrafluoroborate as an oxidant. Reaction discovery and optimization, alkene substrate scope, and transformation of the products to differentially protected amino alcohols as well as PHOX ligands are discussed. Mechanistic considerations of low-yielding substrates are addressed, and future directions including use of alkene oxyamination for the synthesis of additional classes of oxazoline-containing ligands are discussed. Chapter 3 covers efforts to elucidate the mechanism of the selenium redox-catalyzed syn¬-diamination reaction. Experiments towards mechanism determination included reaction profile determination through continuous reaction monitoring by 19F NMR, initial rate kinetics, assessment of any non-linear effects, probing for radical intermediates, evaluation of isolable species of reactions at partial conversion, and attempted syntheses of postulated intermediates along the proposed catalytic cycle. Along the way, the effects of reaction parameters including concentration, identity of solvent, urea nucleophile, oxidant, and diselenide were evaluated.
Graduation Semester
2023-08
Type of Resource
Thesis
Copyright and License Information
Copyright 2023 Emily Mumford

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