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http://arks.princeton.edu/ark:/88435/dsp01c247dw46m
Title: | Cooperative Phosphine-Photoredox Catalysis Enables N-H Activation |
Authors: | Sedillo, Kassandra Faye |
Advisors: | Doyle, Abigail G Knowles, Robert R |
Contributors: | Chemistry Department |
Keywords: | N-H activation nitrogen centered radicals Olefin hydroamination phosphine catalysis phosphoranyl radicals photoredox catalysis |
Subjects: | Organic chemistry |
Issue Date: | 2024 |
Publisher: | Princeton, NJ : Princeton University |
Abstract: | Ideal chemical reactions access valuable products from feedstock chemicals under mildconditions in a robust and high-yielding fashion. However, straightforward achievement of molecular complexity proves challenging due to the inertness of strong bonds in abundant chemicals. Many reactions thus necessitate forcing conditions that impose limitations on the reaction scope, stoichiometric quantities of sacrificial reagents that produce excessive waste, or additional synthetic manipulations to pre-activate the substrate. As a result, developing sustainable and efficient catalytic methodologies remains in high demand. One approach to chemical reaction development is to leverage underexplored reactive intermediates. In this regard, phosphoranyl radicals have become interesting intermediates to explore and to effect mild activation of otherwise inert X–Y bonds. The Doyle group was among the first to discover that photoredox catalysis allows formation of phosphoranyl radicals under mild conditions via single-electron oxidation of a P(III) species followed by nucleophilic addition. The mild generation of these intermediates offers new opportunities for reaction development. A clear understanding of phosphoranyl radical reactivity pathways facilitated the design of selective α-scission fragmentation, ultimately resulting in the development of a novel phosphine catalytic pathway. This new cooperative phosphine-photoredox catalytic strategy has enabled direct N–H bond activation of primary sulfonamides and a diverse array of N–H heteroarenes to deliver versatile N-centered radical intermediates. Various secondary sulfonamides and Nalkylated heteroarenes were formed via intermolecular hydroamination of unactivated olefins. It is anticipated that with improved understanding of the reactivity and selectivity of phosphoranyl radicals, it will be possible to further expand the diversity of nucleophiles and reaction classes capable of interfacing with this platform and apply this strategy in new synthetic contexts. |
URI: | http://arks.princeton.edu/ark:/88435/dsp01c247dw46m |
Type of Material: | Academic dissertations (Ph.D.) |
Language: | en |
Appears in Collections: | Chemistry |
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