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 20 of 33 for “"Chiral ligand"”.
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The Application of sSPhos as a Chiral Ligand in Palladium-Catalysed Reactions: Arylative Dearomatisations, and Heteroarylative Cyclisations with Alkenes
… to all our results is the use of a sulfonated chiral ligand, sSPhos. This ligand was first reported in 2005 by Anderson and Buchwald for performing cross-coupling reactions in water. It was repurposed by the Phipps group, first to control site-selectivity in cross-coupling reactions, and then …
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The Synthesis and Application of a Chiral Sulfonated Phosphine Ligand to Asymmetric Transition-Metal Catalysis
This thesis describes the synthesis of a chiral sulfonated phosphine ligand, sSPhos, in its enantiopure form and its subsequent application in asymmetric transition-metal catalysis. sSPhos is a dialkylbiaryl phosphine ligand bearing a sulfonate group. This sulfonate group can engage in non-covalent …
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Dynamics and Catalytic Resolution of Selected Chiral Organolithiums
… using stoichiometric amounts of the chiral ligand. When this concept is implemented successfully, it obviates the need for covalently attached chiral auxiliary based methods, asymmetric deprotonation, and asymmetric synthesis of a precursor stannane as ways to access enantioenriched …
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Enantioselective lateral lithiation-substitution reactions using benzamide directing groups
… reagents under the influence of the chiral ligand to affect the enantioselective replacement of a carbon-proton bond with a carbon-carbon bond or a carbon-heteroatom bond are described.
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Intermolecular and intramolecular asymmetric induction at the beta-benzylic position of carboxamides in directed lithiation-substitution sequences
… by using ($-$)-sparteine as the external chiral ligand and intramolecularly by using $\alpha$-methylbenzylamine as the covalently attached chiral auxiliary.
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Mechanistic studies of asymmetric induction at benzylic centers of organolithium species
… with butyllithium in the presence of the chiral ligand (${-}$)-sparteine to generate their benzyllithium intermediates, which are subsequently reacted with electrophiles to yield highly enantioenriched products. For N-benzyl-N-Boc-N-3-chloropropyl amine, the electrophile is a part of the …
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Planar chirale Metallocene
The element of planar chirality turned out to be of special importance to achieve high enantioselectivities in various asymmetric processes. In the course of this PhD thesis, the sulfoximine unit was established as a new chiral ortho-directing group for ferrocenes. By variation of the metal …
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Oxo-metal catalysed reactions of unsaturated alcohols
… oxo-molybdenum complexes containing bulky and/or chiral ligand systems have been prepared and their application as potential catalysts for regio and/or asymmetric epoxidation has been studied. A synthesis of the oxo-vanadium complex of the known ligand NN''-ethylenebis(iminomethylCcunphof ) was …
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Chirale intramolekular koordinierte Alane
… Cl, Me, tBu, Cp, and indenyl) incorporating the chiral ligand Ar* =2-[1-(S)-Me2NCH(Me)]C6H4, have been synthesized by salt metathesis reaction and have been characterized by multinuclear NMR (1H, 13C, 27Al), mass spectrometry and elemental analysis. The molecular structures of Ar*2AlBr, Ar*2AlCl, …
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Asymmetric cyclopropanation via catalysts incorporating the 1,4-diol ligands and the newly designed dioxaborolane /
… new methodology for the asymmetric synthesis of chiral organic compounds is a major focus in modem organic chemistry. The use of chiral catalysts is replacing chiral auxiliaries as a new tool for synthetic chemists. An efficient chiral catalyst allows for large quantities of optically active …
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Palladium-Catalysed Functionalisation of Csp3–H Bonds Directed by Aliphatic Amines
… enantioselective functionalisation using a chiral ligand and a preliminary study of stoichiometric aminoalkyl palladium(II) complexes.
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Metal based asymmetric catalysis in Baeyer-Villiger oxidations
… of the substitution pattern of the binaphthyl ligand. The introduction of electron-withdrawing groups in position 6 and 6' of the binaphthyl scaffold had a positive influence on the enantioselectivity, affording lactones with up to 81% ee at full conversion. A further investigation was …
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Applications of planar-chiral phosphaferrocene-oxazolines in asymmetric catalysis and enantioselective desymmetrization by carbon nucleophiles in the presence of chiral ligands
In PART I, the design and the synthesis of planar-chiral phosphaferrocene-oxazolines, a new class of P,N-ligands, are described. The modular nature of their structure allows easy access to a number of analogues in enantiomerically pure forms, facilitating the easy tunability of the chiral …
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The development and synthetic applications of Ti- and Pd-catalyzed processes
… key finding was the influence of the supporting ligand on the observed regioselectivity. Bidentate ligands with a small bite angle such as dppe allow for exclusive arylation at the y-position. As a novel application of this chemistry, we also developed a one-pot domino reaction of 2-bromoanilines …
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Catalytic allylation of aldehydes mediated via the water-gas shift reaction
… was sought through the addition of both free chiral ligand and pre-complexed metal catalysts. While successful in the generation of enantioenriched homoallylic alcohol products, synthetically viable er values were not able to be obtained using the current class of ligand backbones. Finally, …
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Palladium-katalysierte enantioselektive Umlagerung allylischer O-Thiocarbamate
… were synthesized with alkyl isothiocyanates. As chiral ligand a bisphosphane ligand was used. With this ligand and Pd2(dba)3·CHCl3 as precatalyst the rearrangement of acyclic as cyclic thiocarbamates was achieved at roomtemperature with complete conversion. The products of this reaction were …
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Control of selectivity in palladium-catalysed cross-coupling reactions using a sulfonated phosphine ligand
… members of the privileged dialkylbiarylphosphine ligand class, specifically sSPhos, which is the commercially available sulfonated variant of SPhos. The first part investigates the use of this ligand to impart site-selectivity in the cross-coupling of 3,4-dichloroarenes containing an acidic …
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Stereoselective Intramolecular Rhodium(I)-Catalyzed [(3+2+2)] Cycloaddition Reactions of Alkylidenecyclopropanes (ACPs) for the Concise Synthesis of Bridged Tricyclic Products
… of ACPs and the emergence of asymmetric chiral counteranion-directed catalysis (ACDC) strategies, our work—enantioselective intramolecular rhodium-catalyzed [(3+2+2)] cycloaddition of ACPs leveraging a novel ACDC approach—is discussed. This strategy enables asymmetric induction via the …
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Studies in asymmetric synthesis: I. the asymmetric α-alkylation of N,N-dimethylhydrazones II. the asymmetric aldol-Tishchenko reaction of (S)-tert-butanesulfinyl imines for the introduction of 2, 3, 4 and 5 new chiral centres in one pot
… as ketone synthetic equivalents and the chiral diamine sparteine. The first section of this thesis outlines efforts to further expand the scope of this methodology to include more diverse and challenging electrophiles. As a result, a number of synthetically useful ketones were prepared. …
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Controlling the Regio- and Enantioselectivity of Iridium-Catalysed Arene Borylation Using Sulfonated Bipyridine Ligands
… the design and synthesis of novel bipyridine ligands containing a distal anionic sulfonate group, that when bound to iridium can interact with substrates, either through ion-pairing or hydrogen bonding interactions, controlling the selectivity of the transformation. Building on previous work …
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