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Showing 1 to 11 of 11 for “"allylic substitution"”.
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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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Studies towards the synthesis of trehalamine and the effect of adjacent chiral tertiary and quaternary centers on the metal-catalyzed allylic substitution reaction
Studies were conducted towards advancing a trans-epoxy alcohol, derived from an amino-substituted cyclobutanone, to trehalamine. Efforts to manipulate the epoxy alcohol under standard conditions were hindered by the extraordinary propensity of the system to undergo the Payne rearrangement and the …
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Chirality Transfer in Acyclic Allylic Systems and New Pd-Catalyzed Heck Reaction/C-H Activation Cascades
… part, the use of chirality transfer in acyclic allylic systems was assessed for an intra- and an intermolecular reaction. The thermal [2,3] sigmatropic rearrangement of acyclic allylic phosphinites proved to be highly enantioselective, even at 110 °C and led to enantiomerically pure allylic …
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Stereoselective synthesis of artificial C-nucleosides
… both families of target compounds (asymmetric allylic substitution, and ring-closing metathesis). D4 C nucleoside analogues are synthesised in a three step procedure, and 1’-aryl ribofuranoses are constructed in a four step procedure. The target compounds were prepared in an excellent enantio …
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Synthese von planar chiralen Imidazoliumsalzen, ihren Metall-Carbenkomplexen und deren Verwendung in der asymmetrischen Katalyse
… catalytic properties in the palladium-catalyzed allylic substitution. Finally, the application of paracyclophanylimidazolium salts in the rhodium-catalyzed, asymmetric addition of arylboronic acids to aromatic aldehydes to give diarylmethanols was investigated.
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Asymmetrische Synthese von allylischen Alkoholen mittels Palladium-katalysierter asymmetrischer Transformation von allylischen Carbonaten und Synthese neuer Sulfoximin-Phosphane
… synthesis of synthetically interesting allylic alcohols by Palladium-catalyzed allylic substitution. For this substitution reaction the hydrogen carbonate ions are used as nucleophil and racemic allylic carbonates or acetates as racemic substrates. This reaction can also be called …
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Sequential Enantioselective Iridium-Catalyzed Allylic Alkylation/Cope Rearrangement for the Construction of Acyclic γ-Tertiary or Quaternary Stereocenters
… 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 regio- and …
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Synthesis and application of chiral dienes and chiral imidates as ligands for transition metal catalysis
… the best result was obtained in the asymmetric allylic alkylation with an imidate with a binaphtylbackbone: a moderate yield (53% yield) with an excellent selectivity (95% ee). Futhermore, we developed successfully hybrid imidate-phosphane ligands as a new type of P,N ligands. These ligands are …
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Reactions and properties of the isomeric dihydrothiophene 1, 1- dioxides
… were employed with I and II. The expected allylic substitution of bromine in I at the 2 or 5 position and in II at the 3 position was not obtained but rather addition to the double bond of I and II occurred. The dehydrobromination reaction of 3,4-dibromo-tetrahydrothiophene 1,1-dioxide (V) …
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Developments of time-resolved XAFS spectroscopy techniques - applications in homogeneous catalysis
… different inactive Pd-clusters formed during the allylic substitution reaction as a function of ligand and solvent are studied in detail. In Chapter 7 it is shown that the application of a wide range of spectroscopic techniques gives detailed structural and electronic information on the reaction …
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Synthesis of chiral phosphino-sulfoximines through phospha-Michael addition and their evaluation as 1,5-P,N-Ligand in asymmetric allylic alkylation
… 1,5-P,N-ligand in palladium-catalyzed asymmetric allylic alkylation. The key step of the synthesis of phosphino-sulfoximines is the introduction of the phosphorus via a phospha-Michael addition with enantiomerically pure vinyl sulfoximines using diphenylphosphine and a catalytic amount of …