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Showing 1 to 20 of 33 for “"olefination"”.
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Synthetic Studies Towards the Gombaspiroketals and a Cobalt-Catalysed Epoxide Olefination
… the gombaspiroketals, a cobalt-catalysed epoxide olefination to homoallylic alcohols was investigated. This thesis describes the discovery, synthetic utility, and mechanistic considerations of this novel methodology.
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Chiral phosphonyl and thiophosphonyl carbanions in asymmetric alkylation and olefination reactions
A series of 3-substituted 2-benzyl-6-methyl-1,3,2-oxazaphosphorinane-2-oxides, derived from (S)-N-alkyl-4-amino-2-butanols, 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 …
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JULIA-KOCIENSKI APPROACH TO 4-SUBSTITUTED 1- ALKENYL-1H-1,2,3-TRIAZOLES
… 4-substituted triazoles with a Julia-Kocienski olefination handle attached at the N1 atom of the triazole. Olefination reactions of triazole-derived Julia-Kocienski reagents with paraformaldehyde gave 1-ethenyl-1H-1,2,3-triazoles. Heck reactions of these products with phenyl or p-methoxyphenyl …
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Viridiofungins and xeniolide F: target oriented synthesis using different rearrangement reactions of a common substrate class
… double bond was formed by a Julia-Kocienski olefination. During the studies toward the total synthesis of xeniolide F a new, diastereoselective strategy for the generation of allyl vinyl ethers with E-configured vinyl ether double bond was established employing rhodium catalyzed OH-insertion …
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I. Chemoselective Dehydrative Glycosylation With Application Toward Oligosaccharide Synthesis. II. Sulfide-Mediated Direct Glycosylation of C(1)-Hydroxyl Glycosyl Donors. III. Studies Toward the Total Synthesis of Auriside A
… Mitsunobu macrolactonization, and the Julia olefination for the installation of the C(5)-stereogenic center, the 14-membered macrolactone, and the conjugated bromodiene moiety, respectively.
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Ligand-Driven Development of Pd-Catalyzed Nondirected C–H Activation of Arenes
… describes the development of a nondirected C–H olefination method for the late-stage installation of clickable alkyne motifs into (hetero)arenes. Using a dual-ligand palladium catalyst system based on an N-acylsulfonamide (NASA) ligand and a pyrazine-derived ligand, the methodology enables broad …
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Studies on the use of alpha-silyl substituted carbanions in organic synthesis
The stereochemical outcome of the Peterson olefination reaction was studied using o(-trimethylsilylbenzyl carbanion and a series of N-aliphatic/aromatic azomethines. All reactions led stereoselectively to trans-olefins in moderate to low yields. The Peterson intermediate was isolated when …
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Studies Towards the Total Synthesis of the Chivosazoles
… chivosazole F. Optimised Still-Gennari-type HWE olefination conditions were applied to install the (2Z,4E)-dienoate in D. MnO2-mediated double oxidation of D turned the terminal alcohol into an aldehyde and the oxazoline into an oxazole, followed by a Stork-Zhao olefination transforming the …
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Accessing Challenging Fluorinated Motifs Using Photoredox Catalysis And Enabling Technologies
… and diversification of the Peterson olefination. In the first method, one-step access to α–trifluoromethylalkenes is achieved through the cross-coupling of a 3,3,3-trifluoro-1-propenyl trifluoroborate. Alternatively, access to diversified α–trifluoromethylalkenes via the Peterson …
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Total Synthesis of the 2-Nitropyrrole Natural Product Heronapyrrole C
… the desired alkene 136, the Julia-Kocienski olefination of aldehyde 186 and sulfone 187 afforded stereoisomeric mixtures of 136. The low efficiency encountered in preparation of sulfone 187 also limited further investigation of this strategy. A revised strategy was next developed, utilising …
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ΣΥΝΘΕΣΗ ΚΑΙ ΧΗΜΕΙΟΦΩΤΑΥΓΕΙΑ ΔΙΥΠΟΚΑΤΕΣΤΗΜΕΝΩΝ ΣΤΙΛΒΕΝΙΩΝ
… IN GOOD YIELDS BY THE WITTIG CARBONYL OLEFINATION REACTION. THE OZONOLYSIS OF THESE STILBENOLS WAS FOUND TO BE CHEMILUMINESCENT, THE QUANTUM YIELDS (1,2X10-4 - 8,1X10-6) DEPENDING ON HAMMETT'S "6" CONSTANT FOR THE 4'- SUBSTITUENT, AND SALICYLALDEHYDE ANION WAS FOUND TO BE THE PRIMARY …
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Computational analysis and partialsynthesis of resolvin analogues
… oxidation of an alcohol to an aldehyde, a Wittig olefination and, finally, a comprehensive trial of acetal deprotection methods for a 1,2 dioxane acetal in the presence of a silyl ether. Chapter 5 summarises the overall findings of this project and outlines possible future avenues for exploration. …
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Towards the total syntheses of aspidospermidine and aspidofractinine: the curious chemistry of the indolinyl radical
… a highly efficient Stille coupling and a Wittig olefination. Attempts to effect a critical radical cyclisation reaction are also discussed. The chemistry of the C2 indolinyl radical is investigated, in particular the influence of the C3 indolinyl substitution upon the radical pathway followed. A …
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Synthesis and Biological Evaluation of Rigid Analogues of Methamphetamines
… analogs were prepared via a Wittig olefination via the ylides generated from the corresponding triphenylphosphonium benzylhalide salts. The substituted benzylazetidine analogs were synthesized from the corresponding benzylideneazetidienes via hydrogention over palladium and platinum …
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The use of chiral auxiliaries in the synthesis of chemically and biologically important chiral compunds
… and an intramolecular Horner-Wadsworth-Emmons olefination for construction of the E-enone of the macrolide.
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I. Progress Toward Leiodelide A II. Palladium-Catalyzed Reactions of Enol Ethers
… for greater screening of conditions for the olefination step. The side chain producing the greatest selectivity for the desired E-geometry will be used to connect the side chain to the macrolactone in the penultimate step. The northern hemisphere was synthesized from D-xylose producing both …
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Zirconium-mediated alkyene-aldehyde coupling, rhodium-catalyzed alkene hydrothiolation, and copper-catalyzed alkyne hydroarylation: Reaction development and mechanistic investigations
… targets which are often synthesized though the olefination of a carbonyl with an ylide. These reactions produce a stoichiometric amount of byproduct, such as triphenylphosphine oxide in the Wittig olefination. We sought the develop a zirconium–oxo-catalyzed alkyne-aldehyde coupling reaction to …
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Fused and spiro furanones from tetronic acid synthons: Oxa and azacycles featuring the butenolide ring
… in a domino reaction (addition – Wittig olefination) and by direct allylation of tetronic acid via Fischer esterification. 3-Allyl tetronic acids were generated by Claisen rearrangement of 4-O-allyl tetronates under microwave conditions; a subsequent Conia reaction produced the …
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Progress Toward The Total Synthesis Of The Natural Product Herbicide Ascaulitoxin Aglycone
… moderately successful, but abandoned in favor of olefination protocols. Strategy 2 invoked the Wittig reaction as a key reaction for the formation of a C4-C5 olefin, but was also abandoned due to lack of reactivity of an unstabilized ylide with an advanced aldehyde coupling partner. The key C4-C5 …
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