Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 13 of 13 for “"iridium catalyzed"”.
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Iridium-Catalyzed Enantioselective Allylation of Alkenyl Boronates
… Additionally, select examples of iridium-catalyzed nucleophilic substitution reactions will be examined. The second chapter describes the reaction of alkenyl boronates with allylic carbonates to generate tertiary bis-homoallyl boronic esters with high enantioselectivity and …
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Mechanistic studies on iridium catalyzed allylic substitution
Mechanistic studies on iridium catalyzed allylic substitution reactions catalyzed by iridium phosphoramidite complexes revealed that the active catalyst is generated through a base assisted cyclometalation of the phosphoramidite to form five-membered iridacycle. A mechanism for the reaction was …
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Bipyridine Ligands for use in Polymer-Supported Iridium Catalyzed C-H Borylation
… such as 4, 4’-tert-butyl-bipyrine with an iridium precatalyst afford a highly efficient C-H borylation, but studies of polymer-supported bipyridine ligands have not been extensively researched. With an aim to exploring this approach to allow recycling of the expensive iridium catalysts …
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Iridium-catalyzed borylation of aromatic and aliphatic C-H bonds: methodology and mechanism
… conduct the one-pot, meta cyanation of arenes by iridium-catalyzed C-H borylation and copper-mediated cyanation of the resulting arylboronate esters is described in Chapter 2. This process relies on a previously unknown method to conduct the cyanation of arylboronic esters, and conditions for this …
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A hydrogen bonding ortho-directing effect for the iridium catalyzed borylation of NH(t-BOC) aromatics
… and others act as steric obstacles for the iridium catalyst to avoid. This avoidance of appending groups can be reversed into a directed borylation with monophosphine ligands. Alternatively, the SiMe2H group elicits an ortho-directing effect via oxidative addition to the metal center. …
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Investigating Rings: From Iridium-Catalyzed [4+2] Cycloadditions of Alkynyl Halides to Ring Openings of Cyclopropanated Oxabenzonorbornadiene
This thesis describes two unrelated projects. Iridium-catalyzed intramolecular [4+2] cycloadditions of alkynyl halides were investigated, and the catalyst conditions were optimized for ligand, solvent, and temperature. Several substrates successfully underwent cycloaddition under the optimized …
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Sequential Enantioselective Iridium-Catalyzed Allylic Alkylation/Cope Rearrangement for the Construction of Acyclic γ-Tertiary or Quaternary Stereocenters
… In this way, enantioselective transition metal-catalyzed γ-allylic alkylation reactions have attracted increasing attention, albeit they are typically restricted to cyclic nucleophiles. A direct strategy to construct acyclic γ-allylated carbonyl derivates is underdeveloped due to the challenging …
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New methodologies and approaches to reaction discovery in transition metal catalysis
… synthetic methods have been developed based upon iridium-catalyzed borylation of aromatic and heteroaromatic C-H bonds. A general, one-pot method for alkylation of arenes with the site-selectivity controlled by steric effects as opposed to electronic effects via Ir-catalyzed C-H borylation …
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Diversification of 4-Alkylpyridines: Mining for Reactivity with Alkylidene Dihydropyridines
… demonstrated the utility of ADHPs in palladium-catalyzed reactions. However, the fundamental reactivity of ADHPs remains largely unexplored, with only scattered reports in the literature. We seek to further explore the reactivity of these electron-rich intermediates in different contexts, as new …
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Carbon-carbon bond formation methods for the preparation of shape-persistent architectures
… and utilization of three methodologies: iridium-catalyzed arene C-H borylation; zinc- mediated alkynylations; and Lewis acid promoted Mo nitride-alkyne metathesis, are presented as improvements for the preparation of carbon-rich architectures. In addition, X-ray crystallographic analysis …
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Synthesis of Amphibian Alkaloids and Development of Acetaminophen Analogues
… ee and 86% ee, respectively. An enantioselective iridium-catalyzed N-heterocyclization reaction with either (R)- or (S)-1-phenylethylamine and 1-(5-methoxypyridin-3-yl)-1, 5-pentanediol was employed to generate the 2-(pyridin-3-yl)-piperidine ring system in 69-72% yield. A cis-2, 5-disubstitued …
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Novel Enantiopure ß-Amino Alcohols and ß-Amino Thiols in Asymmetric Catalysis
… then applied as ligands in the ruthenium- and iridium-catalyzed transfer hydrogenation of prochiral ketones. They were shown to be active catalysts, affording in some cases >90% conversion already after 15 minutes, and in all cases ees higher than 80%.
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Total Synthesis of the Unique Pederin Family Member Psymberin & Chemical Studies Toward Saliniketal Family Members: Saliniketal a, Salinisporamycin and Rifsaliniketal
… and the synthetic highlights were including the Iridium-catalyzed bis-allylation of 2,2-imethylpropane-1,3-diol, and a stepwise Sonogashira coupling/cycloisomerization/reduction sequence to construct the dihydroisocoumarin unit. The total synthesis of psymberin and its analogs would provide …