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Showing 1 to 20 of 23 for “"Mukaiyama"”.
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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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The Syntheses of Bis-Guanidium Salts and Their Applications in Asymmetric Mukaiyama Type SN2 Alkylation Reactions
… catalysis of 1,4-dicarbonyl compounds via Mukaiyama type SN2 alkylation reactions. Firstly, a series of bis-guanidium salts were synthesized from commercially available and cheap chiral sources in 4 to 5 steps. For most of the derivatives, the overall yields were good. Synthetic problems …
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Lanthanide-Based Precatalysts For Carbon-Carbon Bond-Forming Reactions In Aqueous Media
… majority of biologically active compounds. The Mukaiyama aldol reaction is a Lewis-acid-catalyzed carbon-carbon bond-forming reaction that has the ability to produce optically active β-hydroxy carbonyls which can be found in many pharmaceuticals and natural products. Because of precatalyst …
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Applications of 2,3-Diketoesters in Organic Synthesis and Stereoselective Transformations
… that are prepared by zinc triflate catalyzed Mukaiyama-aldol condensation of methyl diazoacetoacetates with aldehydes, occurred in quantitative yield to form dihydrofuranols that undergo acid catalyzed dehydration under mild conditions to generate 3-methoxyfuran-2-carboxylates in good yield. …
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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
… is accomplished 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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Quantenchemische Berechnungen zur enantioselektiv katalysierten Aldolreaktion
Die Mukaiyama-Aldolreaktion ist die Umsetzung eines Silylenolethers mit einer Carbonylverbindung in Gegenwart einer Lewis-Säure. Diese Reaktion ist eine wichtige Methode zur Knüpfung einer Kohlenstoff-Kohlenstoff-Bindung in der Organischen Chemie. In der vorliegenden Arbeit wird mittels …
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New adaptations of analytical tools for the study of dynamic interactions of lanthanide-based catalysis in aqueous media
… nitro-aldol, Mannich, Diels-Alder, Michael, Mukaiyama aldol, and Friedal-Crafts reactions due to their hard, electrophilic, and hydrolysis-stable character. </p> <p>Despite their favorable properties, the use of lanthanide triflates in asymmetric carbon-carbon bond formation under aqueous …
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The progress towards the total synthesis of (ent)-MPC1001
… acid was efficiently prepared in six steps via a Mukaiyama aldol reaction by a chiral oxazinone and 3-bromo-4-methoxybenzaldehyde. With the dipole product and the β-hydroxyl-α-amino acid derivative in hand, efforts were focused on the coupling of the two components to afford the DKP. Research was …
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Efforts towards the Total Synthesis of Azaspiracid-3
… EFGHI domain highlighted a chelate controlled Mukaiyama aldol reaction to produce C22-C40 linear precursor, and a DIHMA process to assemble the bridged ketal. With the recognition of bridged ketal and spiroaminal functionality in the FGHI domain, the gold-catalysis to achieve these moieties has …
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Part 1. Lewis Base-Catalyzed Cross-Aldol Reactions of Aldehydes: Preparative and Mechanistic Studies. Part 2. Initial Studies on Lewis Base-Catalyzed Reactions of Silyl Ynol Ethers With Aldehydes
… chiral phosphoramide-catalyzed, enantioselective Mukaiyama-type aldol reactions of acetaldehyde with other aldehydes have been achieved. Aldol products from aromatic aldehydes were obtained in high yields and selectivities. Intermediates in these aldol additions have been spectroscopically …
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Studies directed towards the synthesis of (-)-Ebelactone-A
… enriched 20 devised by Williams, employing a Mukaiyama aldol reaction directed by Oppolzer's sultam to establish the anti-anti stereotriad of the fragment. We modelled the coupling of this to 115 using isobutyraldehyde in place of 20 and vinyl iodide 133 in place of 115, and verified that the …
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Applications of novel boron-nitrogen containing heterocycles : design and synthesis o planar-chiral Lewis acids for stereoselective organic synthesis
… reagents to imines and Lewis acid mediated Mukaiyama aldol reaction of aldehydes with silyl ketene acetals.
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Development of new synthetic methodologies
… Baylis-Hillman type bond formations and Mukaiyama aldol type reactions. These reactions are for either carbon-nitrogen or carbon-carbon bond formations and can result in multifunctionalized products. Efficient nitrogen/halogen sources are studied as electrophiles for electrophilic …
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The Kinetic Resolution of Secondary Alcohols Through A Tandem Enantioselective Silylation and the Synthesis of Bis(Oxazolidinyl)Pyridine Metal-Organic Complexes
… mild conditions in which to carry out the Mukaiyama aldol reaction. The design of a bi-functional organic chiral catalyst, which comprises of a Lewis base acetate anion paired with a chiral quaternary ammonium cinchona alkaloid, is discussed. We found that when the addition of a silyl …
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Quinone-Catalyzed Amine α-C–H and α-C–C Functionalization
… quinone-catalyzed oxidative decarboxylation/Mukaiyama−Mannich addition under mild reaction conditions. Following this discovery, quinone-catalyzed deformylative functionalization of aromatic β-amino alcohols was realized to further demonstrate the synthetic utility of quinone-catalyzed …
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Total syntheses of (±)-dracephalone A and (±)-dracocequinones A and B, progress towards a total synthesis of cassiabudanols A and B, and synthetic studies towards total synthesis of N-oxy-diketopiperazine containing natural products.
… optimization efforts of the route, especially Mukaiyama hydration and diketopiperazine (DKP) formation steps, are discussed to achieve overall 13% yield. An asymmetric synthesis of the tricyclic core of [2.2.3]-Epidithiodiketopiperazines is described. The key step features a diastereoselective …
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Studies Towards the Total Synthesis of the Chivosazoles
… of fragment C was defined with a vinylogous Mukaiyama aldol reaction. Site-selective Stille cross-coupling reactions of the three fragments, via a one-pot process, rapidly installed the requisite stereodefined polyene motifs within chivosazole F. Optimised Still-Gennari-type HWE olefination …
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Rhodium-Catalyzed Asymmetric Ring Opening of Oxabicyclic Alkenes and Palladium-Catalyzed Carbon-Halogen Bond Forming Reactions
… ethers and ketene acetals. In analogy to the Mukaiyama aldol reaction, a novel silyl migration occurs, enabling an in situ protection of the chiral alcohols obtained. Developing new reactivity from Heck-type carbopalladation processes represents another research interest in the Lautens group. …
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Design and Synthesis of Natural and Unnatural Macrocycles
… moiety was efficiently accomplished utilizing Mukaiyama aldol, Bayer–Villeger reaction, and addition of lithium dimethyl cuprate. Synthesis of the thiazolidine fragment was investigated via oxa-conjugate addition and Pummerer-type rearrangements. Finally, the alkyl chain fragment was …
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Total synthesis of polycyclic natural products : synthetic studies on (+)-ineleganolide, (–)-sinulochmodin C, verrillin hydrate, and aleutianamine.
… approach was a novel application of a vinylogous Mukaiyama-Michael reaction between a siloxythiophene and a pyrroloquinone monoketal. A sequence of skeletal rearrangements and carbon-nitrogen bond formations then allowed for completion of the total synthesis.
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