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Showing 1 to 20 of 49 for “"Aldol Reaction"”.
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The tandem chain extension -aldol reaction of beta-keto esters
<p>The Tandem Chain Extension-Aldol (TCEA) Reaction of beta-keto esters with aliphatic and aromatic aldehydes yields gamma-keto-beta'-hydroxy esters with significant syn-selectivity. A control Reformatsky reaction with a methyl 2-iodo-5,5-dimethyl-4-oxo-hexanoate 53 and methyl …
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New chiral catalyts for the asymmetric Mukaiyama-type aldol reaction
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1994.
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DFT Studies of the Organocatalytic Aldol Reaction and a Frustrated Lewis Pair
… study of the organocatalytic α-chlorination-aldol reaction and the chiral backbone Frustrated Lewis Pair (FLP) system served as a valuable tool for experimental purposes. This thesis describes methods to consider different transition states of the proline- catalyzed α-chlorination aldol …
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Studies on the Phospho-Aldol Reaction Catalysed by Aluminium Salcyan and Related Complexes
The phospho-aldol (PA) reaction is one of the most versatile reactions for the formation of phosphorus-carbon [P-C] bonds. The reaction is a base-catalysed addition reaction between a hydrogen-phosphonate ester and a carbonyl substrate, affording alpha-functionalised phosphonate esters. These PA …
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Investigations of transition state geometry in the intramolecular aldol reaction and the intramolecular reaction of allylsilanes with aldehydes
… influence the transition state geometry of the aldol reaction are described. Synthesis of two bicyclic model systems designed to study base-catalyzed intramolecular aldol reactions are reported, along with the effects that various metal counterions, solvents, and additives have on the …
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Synthesis of Resveratrol and Its Analogs, Phase-Transfer Catalyzed Asymmetric Glycolate Aldol Reaction, and Total Synthesis of 8,9-Methylamido-Geldanamycin
… have been made using a decarbonylative Heck reaction. The acid chloride derived from 3,5-dihydroxybenzoic acid was coupled with suitable protected 4-hydroxystyrene in the presence of palladium acetate and N,N-bis-(2,6-diisopropylphenyl)-4,5-dihydro imidazolium chloride to give the substituted …
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Towards the synthesis of hyacinthacines
The organocatalytic aldol reaction of tropinone with benzaldehyde using (S)-5-pyrrolidin-2-yl-1H-tetrazole as organocatalyst is described and it results in the formation of the dehydrated aldol adduct in moderate selectivity. The organocatalytic aldol reaction of CS and C2V-symmetrical dioxanones …
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I The tandem chain extension-acylation reaction II Synthesis of papyracillic acid A: Application of the tandem homologation-acylation reaction III Synthesis of tetrahydrofuran-based peptidomimetics
… zinc-mediated tandem chain extension-acylation reaction was successfully developed. This reaction was optimized with the use of beta-keto esters, amides, and imides as well as a variety of acylating agents. The tandem homologation-acylation reaction was successfully applied towards the total …
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Chemistry with chiral lithium amides: enantiotopic group and face-selective reactions
The accomplishment of the γ-alkylation reaction from β-keto esters of tropinone and the enantioselective aziridine formation from nortropinone is first reported. This opened two new paths to develop tropinone enolate chemistry. One is indirect α-alkylation of tropinone, another is the nucleophilic …
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Thiopyran route to polypropionates : simultaneous-two directional and enantiotopic group selective aldol reactions
The sequential aldol reactions of thiopyran derivatives 112 and 119 to rapidly generate hexapropionate building blocks in two carbon-carbon forming steps has been well studied within the Ward group. An extension of this strategy to generate non-racemic tetra- and hexapropionate fragments involved …
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I Progress towards the synthesis of plakortether B through a zinc-mediated homologation II Synthesis of novel hydroxy-cyclopropyl peptides isosteres
… B through a zinc-mediated homologation-aldol reaction has been developed. This chemistry was performed on a chiral beta-keto amide, which was synthesized in a few steps. In a one-pot reaction the beta-keto amide could be converted into a furanyl-ketal with high stereocontrol at two …
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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
… in 17 linear steps using the Mukaiyama aldol reaction, the intramolecular 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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I Peptide isosteric replacement preparation using zinc-mediated chain extension-aldol reactions II Formal synthesis of (+)-Brefeldin A III Zinc-mediated chain extension reactions with substituted carbenoids
… chain extension and tandem chain extension aldol reactions with various aldehydes and ketones. An efficient diastereoselective synthetic route has been developed to approach a proposed inhibitor for HCMV (Human Cytomegalovirus) protease using this zinc-mediated tandem chain extension-aldol …
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New Methods for the Formation of Methyl Bearing Stereogenic Centers via Methylketene Dimerization and Free Radical Additions to Allyl Bromides
… and 2) a free radical-based addition/elimination reaction involving allyl bromides. The first method, the asymmetric dimerization of methyl ketene, followed by an asymmetric aldol reaction and the appropriate functional group manipulations enabled us to construct the (2S, 4S, 6S) trimethylnonyl …
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Synthesis and catalytic testing of a proline functionalized amphiphilic block copolymer
… used to reduce the amount of energy that a reaction needs to execute, allowing it to proceed at a higher rate while not being consumed. The use of catalyst functionalized amphiphilic copolymer allows easier recovery of the catalyst at the end of the synthesis and allows for the reaction. In …
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METHODOLOGY DEVELOPMENT OF N-SULFINYL METALLOENAMINES AND ASYMMETRIC TOTAL SYNTHESIS OF (+)-EPIIBOGAMINE
… (+)-chimonanthine is described. The vinylogous aldol reaction of N-sulfinyl metallodienamines was first reported in 2017 in the total synthesis of (−)-albocycline. However, the diastereoselectivity of this reaction was found to be incorrectly reported. Mosher ester analysis and HPLC analysis …
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An excursion into the synthesis of novel flavanones
… The designated approach was via an asymmetric aldol reaction catalysed by a chiral organocatalyst followed by an intramolecular Mitsunobu reaction. Following a review of the existing methodologies for the synthesis of racemic and asymmetric flavanones and various flavan analogues, an initial …
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The asymmetric synthesis of (2S,3R)-capreomycidine and the total synthesis of capreomycin IB
… features a novel aluminum enolate-aldimine reaction with a chiral glycinate, which sets both stereocenters. A concise and high-yielding approach to the unnatural amino acid (2S,3S)-β-hydroxyornithine is also reported. The key step in this approach is a boron-mediated aldol reaction with a …
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I Ceric ammonium nitrate-mediated oxidative cleavages of hemiacetals II Synthesis of beta-proline derivatives through the tandem chain extension-imine capture reaction
… zinc carbenoid-mediated tandem chain extension-aldol reaction was developed. This chemistry has been applied towards the formation of a class of natural products, phaseolinic acids, in two steps from a commercially available beta-keto ester, methyl 4-methoxyacetoacetate.</p><p>The tandem chain …
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