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 “"asymmetric alkylation"”.
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Probing the mechanism of the asymmetric alkylation of pseudoephedrine amides
… and his co-workers proposed a mechanism for this asymmetric alkylation which assumes that a dianion is formed with the alcohol and the enolate that prevents the formation of the undesired diastereomer. Results by D.J. Procter and his co-workers using immobilized pseudoephedrine amides on a …
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Chiral phosphonyl and thiophosphonyl carbanions in asymmetric alkylation and olefination reactions
… was prepared. The alkylation behavior of the derived lithium anions was examined as a function of the N-substituents and electrophiles. In the l-series, the methylation proceeded with high diastereoselectivity (90/10-97/3) and the benzylation selectivity ranged from …
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Total Syntheses of (+)-Geldanamycin, (-)-Ragaglitazar, and (+)-Kurasoin A and Phase-Transfer-Catalyzed Asymmetric Alkylation
… formation of GA and future synthetic analogs. Asymmetric glycolate alkylation has been developed using phase-transfer-catalysis (PTC). Diphenylmethoxy-2,5-dimethoxyacetophenone with trifluorobenzyl cinchonidinium catalyst and cesium hydroxide provided alkylation products at —35 °C in high yield …
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Studies in asymmetric synthesis I the asymmetric alpha-alkylation of N,N-dimethylhydrazones II the synthesis of 1,3-amino alcohols via the aldol-Tishchenko reaction
… found widespread use in total synthesis. The asymmetric alkylation of ketones represents one of the most powerful and longstanding procedures in organic chemistry. Surprisingly, however, only one effective methodology is available, and this involves the use of chiral auxiliaries. Part I of …
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New methods for the asymmetric synthesis of α-alkylated ketones and 1,3-amino alcohols
… found widespread use in total synthesis. The asymmetric alkylation of ketones represents one of the most powerful and longstanding procedures in organic chemistry. Surprisingly, however, only one effective methodology is available, and this involves the use of chiral auxiliaries. This is …
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Diversification of 4-Alkylpyridines: Mining for Reactivity with Alkylidene Dihydropyridines
… under mild conditions, and the iridium-catalyzed asymmetric alkylation of alkylidene dihydropyridines branch-allylated alkyl pyridines.
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Progress in nucleophilic catalysis and development of nickel-catalyzed cross-couplings of propargylic halides
… two organocatalytic processes. The first is a 13-alkylation reaction of Michael acceptors, and represents a novel umpolung process catalyzed by N-heterocyclic carbenes. The second section discusses the first successful phosphine-catalyzed, y-alkylation reaction of isomerizable allenoates. A highly …
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The study of the asymmetric synthesis of lignans
The work in this thesis focuses on the asymmetric synthesis of lignans by approaches such as Diels-Alder reactions, asymmetric alkylation reactions, and intramolecular oxidative coupling reactions. In addition to developing asymmetric synthetic methodologies for chiral lignans, an investigation of …
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Stereoselective synthesis : studies involving dipole-stabilized carbanions alpha to nitrogen
… the current mechanistic understanding of asymmetric carbon-carbon bond formation adjacent to nitrogen. A brief literature review is presented to illustrate the different ways in which a stereoselective lithiation/substitution reaction at carbon can occur. A review of the application of …
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Phase transfer catalysis: catalyst screening, reaction development, and mechanism analysis
The asymmetric alkylation of a glycine Schiff base in addition to the development of a [2,3]-Wittig rearrangement under phase transfer catalysis (PTC) reaction conditions was investigated. Supplementing these studies, a deeper understanding of the PTC mechanism was sought for the alkylation of …
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Optimalisation de la radiosynthèse et production au niveau de la curie d'acides aminés aromatiques marqués au fluor-18
… enantioselectivity, at room temperature, for the asymmetric alkylation of a N-(diphenylmethylene)glycine tert-butyl ester have been prepared. Two of these catalysts affords high enantiomeric excess in FDOPA and FTYR (e.e. ≥ 95%) at room temperature and even at 75°C (e.e. ≥ 90%). One is readily …