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 11 of 11 for “"Asymmetrische Reaktion"”.
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Asymmetrische Dihydroxylierung (AD) und asymmetrische Aminohydroxylierung (AA) mit immobilisierten Alkaloiden
The Asymmetric Dihydroxylation (AD) and Asymmetric Aminohydroxylation (AA) of olefins introduced by Sharpless represent efficient methods for the preparation of diols respectively vicinal aminoalcohols. Within this thesis the attachment of different ligand types (pyrimidine-, …
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Asymmetrischer Aryltransfer : experimentelle und theoretische Verfahren
The enantioselective aryl transfer to aldehydes and imines using different types of aryl sources was developed within this PhD thesis. The new methods allow access to highly substituted Diarylmethanols, which are not accessible via the existing reductive protocols or the enantioselective phenyl …
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Asymmetrische C-C-Knüpfungsreaktionen mit lithiierten Alkyl- und Allylsulfoximinen
Asymmetric C–C–bonding reactions with lithiated alkyl and allyl sulfoximines This thesis deals with the use of (S)-N,S-dimethylphenylsulfoximine in asymmetric synthesis. The lithiated (S)-N,S-dimethylphenylsulfoximine can react with alpha-, beta-unsaturated carbon acid esters. This Michael-type …
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Vanadium-katalysierte, asymmetrische Epoxidierung von Allylalkoholen
A protocol for the vanadium-catalysed asymmetric epoxidation of allylic alcohols using enantiopure hydroxamic acids as ligands is described. The newly synthesised hydroxamic acids were derived from bicyclo[2.2.1]heptanes containing chiral centres, as well as from planar chiral [2.2]paracyclophanes …
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Asymmetric anhydride opening : optimization and applications
This PhD thesis describes the desymmetrization of easily accessible meso-anhydrides by cinchona alkaloid-mediated opening with benzyl alcohol. This procedure was found to be applicable to a variety of structurally different substrates and leads to the corresponding optically active hemiesters with …
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Neue optisch aktive Phosphoniumsalze als Phasentransferkatalysatoren sowie die Verwendung der korrespondierenden Phosphane in der asymmetrischen Katalyse
Within this thesis, primary the application of optically active phosphoniumsalts in asymmetric phase transfer catalysis is described. Emphasis is placed on the Darzens-reaction of benzaldehyde and chloroacetophenone. First, achiral phosphoniumsalts were used under variation of the structure of the …
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Optically active [(eta 6 -arene)Cr(CO) 3]-based diphosphines : synthesis and application in asymmetric homogeneous hydrogenation
Chiral diphosphines have become an important class of ligands for asymmetric catalysis. It is the success itself of enantioselective catalysis that has enhanced the demand for new chiral ligands for essentially two reasons. The first one is that no class of ligands can be considered universal …
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Metal based asymmetric catalysis in Baeyer-Villiger oxidations
One of the objectives of the present thesis was to improve the efficiency of an aluminium-catalyzed Baeyer-Villiger oxidation. This system was based on a mediating species formed by enantiopure 2,2'-dihydroxy-1,1'-binaphthyl (BINOL) and Me2AlCl and utilized a hydroperoxide as oxidant. A first …
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Palladium-katalysierte kinetische Racematspaltung allylischer Carbonate mit S-Nukleophilen und enantioselektive Umlagerung allylischer O-Sulfinate : asymmetrische Synthese von allylischern Sulfiden und Sulfonen
The palladium(0) catalyzed reactions of symmetrically disubstituted racemic allylic carbonates, being either cyclic or acyclic, with 2-pyrimidinethiol in the presence of N,N'-(1R,2R)-1,2-cyclohexanediyl-bis[2-(diphenylphosphino)-benzamide] BPA as ligand proceed with excellent levels of …
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Axial chirale Phosphite als Liganden in der enantioselektiven Rhodium-katalysierten Hydrierung
In the pharmaceutical and agrochemical industry enantiomerically pure substances become more and more important as drugs or chiral building blocks. The Rhodium-catalyzed hydrogenation is a very effective way to produce such enantiomerically pure substances. Activity and selectivity of the …
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Enantioselective ring opening reactions catalysed by heterogenized metal salen complexes
Epoxides are important intermediates for the stereo controlled synthesis of complex organic enantioselective compounds. Their use has increased dramatically with the advent of practical asymmetric catalytic methods for their synthesis. In the early nineties, Jacobsen et al. designed the chiral …