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Please use this identifier to cite or link to this item: http://arks.princeton.edu/ark:/88435/dsp01zs25xc07q
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dc.contributor.advisorKnowles, Robert R-
dc.contributor.authorChoi, Gilbert-
dc.contributor.otherChemistry Department-
dc.date.accessioned2017-07-17T20:47:13Z-
dc.date.available2018-06-09T08:06:47Z-
dc.date.issued2017-
dc.identifier.urihttp://arks.princeton.edu/ark:/88435/dsp01zs25xc07q-
dc.description.abstractAmidyl radicals are classical intermediates that are well-known to achieve olefin-addition reactions as well as C-H abstractions via hydrogen-atom transfer. Despite their synthetically useful reactivity, methods to generate these radicals with mild and catalytic conditions from the native N-H bonds of amides are not documented. This dissertation describes the development of catalytic protocols in the activation of N-H bonds of amides to perform carboamination, hydroamidation, and C-H abstractions via amidyl radicals. First, through use of the excited state of an iridium photocatalyst and a phosphate base, proton-coupled electron transfer activation of the N-H bond of N-aryl amides was effected. This process generates amidyl radicals, representing a net formal homolysis. These reactive amidyl intermediates could continue by adding into pendant olefins. With an appropriate olefin acceptor or a H-atom donor, carboamination and hydroamidation reaction protocols were developed. These reactions demonstrate broad scopes and functional group compatibility. Furthermore, evidence from luminescence quenching experiments strongly suggest a concerted proton-coupled electron transfer mechanism for these types of activations. This method was extended to N-alkyl amides, which exhibit stronger N-H bond strengths. By developing novel conditions for PCET activation of these much stronger bonds mainly by use of a more oxidizing iridium photocatalyst in its excited state, we could effect distal C-H alkylation reactions along with intermolecular variants. Again, the mechanistic data gathered from these experiments favor the probability of a concerted proton-coupled electron transfer as the mechanism of activation. Finally, by appending the phosphate base to the amide, more efficient yields of intermolecular C-H alkylation product could be obtained. This approach may potentially lend itself further to unique selectivities virtually inaccessible by other means.-
dc.language.isoen-
dc.publisherPrinceton, NJ : Princeton University-
dc.relation.isformatofThe Mudd Manuscript Library retains one bound copy of each dissertation. Search for these copies in the library's main catalog: <a href=http://catalog.princeton.edu> catalog.princeton.edu </a>-
dc.subject.classificationOrganic chemistry-
dc.titleProton-Coupled Electron Transfer in Organic Synthesis: Activation of Amides Towards Challenging Bond Homolyses-
dc.typeAcademic dissertations (Ph.D.)-
pu.projectgrantnumber690-2143-
pu.embargo.terms2018-06-09-
Appears in Collections:Chemistry

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