Lewis base catalyzed enantioselective oxysulfenylation of alkenes

Kornfilt, David Jean Pierre

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

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

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

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

Copyright and License Information

Copyright 2016 David Kornfilt

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