SYNTHESIS OF MODELS FOR NEIGHBORING PROLINE AMIDE AND ARYL PARTICIPATION IN ELECTRON TRANSFER FROM THIOETHERS

Persistent Link:
http://hdl.handle.net/10150/205471
Title:
SYNTHESIS OF MODELS FOR NEIGHBORING PROLINE AMIDE AND ARYL PARTICIPATION IN ELECTRON TRANSFER FROM THIOETHERS
Author:
Yamamoto, Takuhei
Issue Date:
2011
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.
Embargo:
Embargo: Release after 12/02/2012
Abstract:
A series of 6-endo-(methylthio)-bicyclo[2.2.1]heptane-2-endo-proline amides was synthesized to study the neighboring proline amide participation in electron transfer from thioethers. The thioether with endo-pyrrolidine amide formed a two-center three-electron SO bond after one electron oxidation and the oxidation potential of the thioether was lowered by 530 mV and 330 mV compared to the corresponding exo-pyrrolidine amide and the primary amide analogues, respectively. The thioether with a proline methyl ester showed the oxidation potential of 410 mV higher than that of the pyrrolidine amide. The basis for this surprising result was revealed by an X-ray crystallographic structure study of the diastereomerically pure proline methyl ester which showed amide carbonyl n → methyl ester π* interaction which removes electron density from the neighboring amide which results in less effective neighboring amide participation in thioether oxidation. This accounts for the electrochemical result. A potent synthetic route for S-tert-butyl m-terphenyl thioethers was developed and a series of such thioethers was synthesized. Electrochemical studies showed through-space S∙∙∙π interaction with lower oxidation potentials for thioethers with more electron rich aromatic groups and higher oxidation potentials with electron withdrawing aromatic groups. Selective Suzuki reactions were discovered in which mono-coupling of the precursor dibromides could be achieved. A second coupling was then possible in which two different aromatic rings are attached to the central aryl thioether ring. This enabled the synthesis of a two-sulfur three-aromatic ring extended m-terphenyl thioether as a potential electron conductor. In support of this possibility this compound showed an oxidation potential of +0.99 V which is less positive than the +1.09 V measured for the mono-sulfur analog.
Type:
text; Electronic Dissertation
Keywords:
neighboring; oxidation; participation; thioether; Chemistry; group; methionine
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Chemistry
Degree Grantor:
University of Arizona
Advisor:
Glass, Richard S.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleSYNTHESIS OF MODELS FOR NEIGHBORING PROLINE AMIDE AND ARYL PARTICIPATION IN ELECTRON TRANSFER FROM THIOETHERSen_US
dc.creatorYamamoto, Takuheien_US
dc.contributor.authorYamamoto, Takuheien_US
dc.date.issued2011-
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.releaseEmbargo: Release after 12/02/2012en_US
dc.description.abstractA series of 6-endo-(methylthio)-bicyclo[2.2.1]heptane-2-endo-proline amides was synthesized to study the neighboring proline amide participation in electron transfer from thioethers. The thioether with endo-pyrrolidine amide formed a two-center three-electron SO bond after one electron oxidation and the oxidation potential of the thioether was lowered by 530 mV and 330 mV compared to the corresponding exo-pyrrolidine amide and the primary amide analogues, respectively. The thioether with a proline methyl ester showed the oxidation potential of 410 mV higher than that of the pyrrolidine amide. The basis for this surprising result was revealed by an X-ray crystallographic structure study of the diastereomerically pure proline methyl ester which showed amide carbonyl n → methyl ester π* interaction which removes electron density from the neighboring amide which results in less effective neighboring amide participation in thioether oxidation. This accounts for the electrochemical result. A potent synthetic route for S-tert-butyl m-terphenyl thioethers was developed and a series of such thioethers was synthesized. Electrochemical studies showed through-space S∙∙∙π interaction with lower oxidation potentials for thioethers with more electron rich aromatic groups and higher oxidation potentials with electron withdrawing aromatic groups. Selective Suzuki reactions were discovered in which mono-coupling of the precursor dibromides could be achieved. A second coupling was then possible in which two different aromatic rings are attached to the central aryl thioether ring. This enabled the synthesis of a two-sulfur three-aromatic ring extended m-terphenyl thioether as a potential electron conductor. In support of this possibility this compound showed an oxidation potential of +0.99 V which is less positive than the +1.09 V measured for the mono-sulfur analog.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectneighboringen_US
dc.subjectoxidationen_US
dc.subjectparticipationen_US
dc.subjectthioetheren_US
dc.subjectChemistryen_US
dc.subjectgroupen_US
dc.subjectmethionineen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorGlass, Richard S.en_US
dc.contributor.committeememberGhosh, Indraneelen_US
dc.contributor.committeememberZheng, Zhipingen_US
dc.contributor.committeememberLichtenberger, Dennis L.en_US
dc.contributor.committeememberGlass, Richard S.en_US
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