University of Illinois Urbana-Champaign

Lewis base catalyzed enantioselective oxysulfenylation of alkenes

Kornfilt, David Jean Pierre

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KORNFILT-DISSERTATION-2016.pdf

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https://hdl.handle.net/2142/95493

Description

Title
Lewis base catalyzed enantioselective oxysulfenylation of alkenes
Author(s)
Kornfilt, David Jean Pierre
Issue Date
2016-11-30
Director of Research (if dissertation) or Advisor (if thesis)
Denmark, Scott E.
Doctoral Committee Chair(s)
Denmark, Scott E.
Committee Member(s)
  • Burke, Martin D.
  • Donk, Wilfred v
  • Rauchfuss, Thomas B.
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Date of Ingest
2017-03-01T16:37:00Z
Keyword(s)
  • Catalysis
  • Lewis Bases
  • Enantioselecive
  • Organocatalysis
Abstract
The Lewis base activation of Lewis acids has been harnessed in the development of an enantioselective oxysulfenylation reaction for unactivated alkenes. The weak Lewis acid N-(phenylthio)-phthalimide can be activated in the presence of a moderate Brønsted acid and chiral Lewis base donors. The resulting complex is a powerful sulfenylating agent capable of sulfenium transfer to simple mono-, di- and trisubstituted alkenes with high selectivity to form enantioenriched thiiranium ions. Stereospecific and site-selective capture of the thiiranium ions furnish vicinally functionalized thioethers. The nucleophile scope of the reaction encompasses alcohols, carboxylic acids and phenols. Both inter- and intramolecular sulfenylation reactions were realized. The reaction is highly robust and individual substrates usually did not require reoptimization. Mechanistic, X-ray crystallographic and kinetic investigations enabled a complete catalytic cycle to be formulated. The proposed cycle was supported by both kinetic data and the characterization of reaction intermediates. The turnover-limiting and enantiodetermining steps were identified as thiiranium ion formation. X-ray crystallography of the active sulfenylating agent did not immediately identify a basis for the high selectivity. Instead, the origin of selectivity in the reaction of trans-alkenes was determined to be distortion-based with the aid of computational models.
Graduation Semester
2016-12
Type of Resource
text
Permalink
http://hdl.handle.net/2142/95493
Copyright and License Information
Copyright 2016 David Kornfilt

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