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Title:Lewis base catalyzed enantioselective oxysulfenylation of alkenes
Author(s):Kornfilt, David Jean Pierre
Director of Research:Denmark, Scott E
Doctoral Committee Chair(s):Denmark, Scott E
Doctoral Committee Member(s):Burke, Martin D; Donk, Wilfred v; Rauchfuss, Thomas B
Department / Program:Chemistry
Discipline:Chemistry
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(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.
Issue Date:2016-11-30
Type:Thesis
URI:http://hdl.handle.net/2142/95493
Rights Information:Copyright 2016 David Kornfilt
Date Available in IDEALS:2017-03-01
Date Deposited:2016-12


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