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 174 for “"Asymmetrische"”.
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Asymmetrische Pinakolkupplungen
Generally, there are two different strategies for asymmetric pinacol couplings. One is to take enantiopure carbonyl compounds as starting materials and the other to introduce chirality using chiral coupling reagents. In this Ph. D. thesis both strategies were investigated. Using the SAMP / RAMP …
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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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Asymmetrische Synthese von Sulfonsäurederivaten
Sulfonic acids and its derivatives are an important class of organic compounds. There are many sulfonic acids and derivatives with interesting pharmacological properties (e.g. taurine). The main objective in this dissertation was the synthesis of various protected taurine-derivatives. Additionally, …
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Asymmetrische Cycloisomerisierung von 1,6-Dienen
Within this thesis an highly selective and active catalyst system for the cycloisomerisation of 1,6-dienes towards exo-methylenecyclopentanes could be developed. The combination of [{Ni(allyl)Br}2], Wilke´s azaphospholene and Na[BARF] led to a catalyst, which transformed diethyl diallylmalonate to …
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Asymmetrische Synthese von 1-Aminocyclobutancarbonsäuren
Ziele dieser Arbeit waren zunächst die Optimierung der Synthese der razemischen 2- Hydroxy-2,3,3-trimethyl-butansäure (4) sowie die Entwicklung einer effizienten Razematspaltung dieser Säure. Nach dem Aufbau des Glycinäquivalents sollte dieses für den stereoselektiven Aufbau 2-substituierter …
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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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Rhodium-katalysierte, asymmetrische Synthese: Ligandendesign und Methodik
The development of new and efficient catalysts is of utterly importance for the improvement of existing reactions and the discovery of new catalytic reactions. On the one hand this PhD thesis deals with the synthesis of novel, enantiopure diphosphines and phosphine-olefin-complexes bearing a …
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Asymmetrische Synthese von Dibenzylbutan- und Dibenzylbutyrolacton-Lignanen
Lignans are a wide spread class of natural compounds which mainly occur in plants as secondary plant metabolites. The term lignans is derived from Latin lignum (wood). Lignans are still very interesting and intensively investigated mostly due to their great variety of medical important …
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Asymmetrische Totalsynthese des hochwirksamen Prostacyclin-Analogons Cicaprost
An asymmetric synthesis of cicaprost and a formal asymmetric synthesis of isocicaprost by a new strategy are described. The key steps of theses syntheses are the coupling of chiral bicyclic C6-C14 alkyne building blocks with a chiral C15-C20 omega-side chain Weinreb-amide building block at the …
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Asymmetrische Synthese von Tarchonanthuslacton und Pironetin-Bausteinen
The natural product Pironetin was isolated from the culture broths Streptomyces sp. NK10958 and Streptomyces prunicolor PA-48153 in 1994 and shows remarkably high antitumor and immunosuppressive activity. Aim of this thesis was an efficient asymmetric synthesis of the aforementioned natural …
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Synthese neuartiger Sulfoximine für die asymmetrische Metallkatalyse
In this work various beta-hydroxysulfoximines was synthesized. We proved their catalytic applicability in asymmetric phenyl transfer reactions onto aldehydes. Enantiomerically enriched diarylmethanols have been prepared by catalyzed asymmetric phenyl transfer reactions onto aromatic aldehydes with …
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Neuartige hochselektive Katalysatoren für die asymmetrische Ketonhydrierung
Für die Entwicklung von Medikamenten und von neuen Produkten im Bereich der Agrarchemie werden häufig chirale Verbindungen benötigt. Für deren Herstellung gibt es bisher keine einzelne Technologie, die man als Patentrezept bezeichnen könnte. Die Synthese solcher Verbindungen mittels Metallkatalyse, …
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