Stabilization of electron-deficient sulfur by neighboring sulfur and oxygen groups.

Persistent Link:
http://hdl.handle.net/10150/184977
Title:
Stabilization of electron-deficient sulfur by neighboring sulfur and oxygen groups.
Author:
Steffen, Lawrence Kraig.
Issue Date:
1989
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The mesocyclic trithioether 1,4,7-trithiacyclononane shows neighboring group participation upon oxidation as evidenced by the peak potential for oxidation in cyclic voltammetry, 0.9 V versus Ag/0.1 M AgNO₃, and by the formation of its monosulfoxide by controlled potential electrolysis in an overall two electron process. Pulse radiolysis of 1,4,7-trithiacyclononane leads to the formation of a two-center three-electron bond of moderate stability. Naptho [1,8-b,c]-1,5-dithiocin shows neighboring group participation upon electrochemical oxidation. A low peak potential is observed, 0.47 V versus Ag/0.1 M AgNO₃, in the cyclic voltammetry. Controlled potential electrolysis leads to formation of the monosulfoxide in a two electron process. The rigid methionine analog (±)-2-exo-amino-6-endo methylthiobicyclo [2.2.1] heptane-2-endo carboxylic acid exhibits neighboring group participation upon electrochemical oxidation. The degree of participation depends on the acid/base chemistry of the α-amino acid. The zwitterion shows the strongest neighboring group participation. Controlled potential electrolysis led to the formation of two diastereomeric sulfoxides in a two electron process. The diastereomer ratio was suggestive of participation by the carboxylate in the oxidation. The structures of the sulfoxides were confirmed by comparison with chemically prepared sulfoxides and sulfoxide amino acid derivatives. The stereochemistry was assigned by comparison with related compounds upon which x-ray crystallographic analysis had been performed. Single-electron pulse radiolytic oxidation of the amino acid led to the formation of an absorbing transient which was assigned to a two-center three-electron sulfur-carboxylate oxygen species. The yield of the species formed was pH dependent. At a pH above 3.5 decarboxylation becomes a major decomposition pathway in contrast to the electrochemical experiments where no decarboxylation was seen. The alcohol (±)-endo-2-hydroxy-6-endo-methylthiobicyclo [2.2.1] heptane shows significant neighboring group participation upon electrochemical oxidation in comparison with its exo-hydroxy isomer as indicated by a 350 mV difference in the peak potentials. Controlled potential electrolysis in a two electron process leads to formation of a mixture of diastereomeric alkoxysulfonium salts.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Chemistry
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Chemistry; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Glass, Richard S.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleStabilization of electron-deficient sulfur by neighboring sulfur and oxygen groups.en_US
dc.creatorSteffen, Lawrence Kraig.en_US
dc.contributor.authorSteffen, Lawrence Kraig.en_US
dc.date.issued1989en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe mesocyclic trithioether 1,4,7-trithiacyclononane shows neighboring group participation upon oxidation as evidenced by the peak potential for oxidation in cyclic voltammetry, 0.9 V versus Ag/0.1 M AgNO₃, and by the formation of its monosulfoxide by controlled potential electrolysis in an overall two electron process. Pulse radiolysis of 1,4,7-trithiacyclononane leads to the formation of a two-center three-electron bond of moderate stability. Naptho [1,8-b,c]-1,5-dithiocin shows neighboring group participation upon electrochemical oxidation. A low peak potential is observed, 0.47 V versus Ag/0.1 M AgNO₃, in the cyclic voltammetry. Controlled potential electrolysis leads to formation of the monosulfoxide in a two electron process. The rigid methionine analog (±)-2-exo-amino-6-endo methylthiobicyclo [2.2.1] heptane-2-endo carboxylic acid exhibits neighboring group participation upon electrochemical oxidation. The degree of participation depends on the acid/base chemistry of the α-amino acid. The zwitterion shows the strongest neighboring group participation. Controlled potential electrolysis led to the formation of two diastereomeric sulfoxides in a two electron process. The diastereomer ratio was suggestive of participation by the carboxylate in the oxidation. The structures of the sulfoxides were confirmed by comparison with chemically prepared sulfoxides and sulfoxide amino acid derivatives. The stereochemistry was assigned by comparison with related compounds upon which x-ray crystallographic analysis had been performed. Single-electron pulse radiolytic oxidation of the amino acid led to the formation of an absorbing transient which was assigned to a two-center three-electron sulfur-carboxylate oxygen species. The yield of the species formed was pH dependent. At a pH above 3.5 decarboxylation becomes a major decomposition pathway in contrast to the electrochemical experiments where no decarboxylation was seen. The alcohol (±)-endo-2-hydroxy-6-endo-methylthiobicyclo [2.2.1] heptane shows significant neighboring group participation upon electrochemical oxidation in comparison with its exo-hydroxy isomer as indicated by a 350 mV difference in the peak potentials. Controlled potential electrolysis in a two electron process leads to formation of a mixture of diastereomeric alkoxysulfonium salts.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectChemistryen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorGlass, Richard S.en_US
dc.contributor.committeememberBates, Robert B.en_US
dc.contributor.committeememberMash, Eugene A.en_US
dc.contributor.committeememberWilson, George S.en_US
dc.contributor.committeememberMiller, Walter B.en_US
dc.identifier.proquest9022114en_US
dc.identifier.oclc706823211en_US
All Items in UA Campus Repository are protected by copyright, with all rights reserved, unless otherwise indicated.