Development of highly efficient palladium catalysts and organic reactions.
Item
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Title
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Development of highly efficient palladium catalysts and organic reactions.
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Identifier
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AAI3283627
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identifier
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3283627
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Creator
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Dong, Chengguo.
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Contributor
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Adviser: Qiao-Sheng Hu
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Date
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2007
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Organic | Chemistry, Polymer
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Abstract
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Over the past decades, Palladium catalyzed bond-forming reactions including cross-coupling reactions are among the most powerful transformations in organic synthesis. It is of our primary concern to develop highly active Palladium catalysts and new reactions/processes to further enhance the efficiency of Palladium catalysis.;We have developed very highly active palladium catalysts that employ rigid and sterically regular monodentate phosphine containing polymers for Suzuki coupling reactions. To achieve extremely highly active palladium catalysts that will be widely applied both in pharmaceutical/chemical development and basic research, we carried out mechanistic studies directed at furnishing insights of the origin of the unusual catalytic activity of monophosphine/Palladium complex in the coupling processes. Our study suggested that bridged dimeric palladiums complexes are relatively stable species with high catalytic activities and 1,3-dipalladium complexes have high catalytic activities in the ferrocenyl-methylphosphine-containing polymers/Palladium catalysts.;Based on our discovery of the reaction mechanism, we pinpointed that the individual elementary steps in each catalytic cycle could be controlled and such a control, especially combined with other bond forming processes, could provide us unprecedented opportunities to develop new reactions/processes; thus making the powerful Palladium-catalyzed cross-coupling reactions be even more powerful for organic synthesis.;We developed Pd(0)/t-Bu3P-catalyzed Suzuki cross-coupling of dihaloarenes with arylboronic acids, a process that relies on the control of oxidative addition step, and defined the concept of "Preferential oxidative addition". The results lead to the development of new, efficient processes to conjugate polymers with controlled length which are potentially useful in molecular electronics. We have also development tandem cross-coupling-cyclization reactions by controlling transmetalation rate, a cyclization process that combines the control of the transmetalation step with sp 3 C-H activation as well as Palladium-Associated Aryne forming processes. This work provides a high yield, one-step access to substituted fluorenes from readily available 1,2-dihalobenzenes and 2-haloaryl arenesulfonates and hindered Grignard reagents. It may find applications in the preparation of substituted fluorene-containing molecules including polymers.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
