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Showing 1 to 20 of 50 for “"Nickel-catalyzed"”.
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Selective, nickel-catalyzed carbon-carbon bond-forming reactions of alkynes
… processes is highly desirable. Several novel, nickel-catalyzed carbon-carbon bond-forming reactions of alkynes that display excellent regioselectivity and (E/Z)-selectivity are described. These reactions afford synthetically useful allylic and homoallylic alcohols, often with high …
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Nickel-catalyzed cross-coupling reactions involving secondary and tertiary alkyl nucleophiles
… first chapter, introduction of transition metal-catalyzed cross-coupling reactions has been given. These transition metal-catalyzed C-C bond forming reactions have been used extensively in organic synthesis. Among them, C(sp2)-C(sp2) bond forming reactions have been widely studied over decades. …
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Total synthesis enabled by nickel-catalyzed transformations: Dearomative carboamination and methylenecyclopropane annulation
… disconnections to be considered. Specifically, nickel catalysis has been emerging as an excellent replacement for traditional palladium-catalyzed transformations, such as Suzuki–Miyaura cross-couplings and Buchwald–Hartwig aminations. However, the use of nickel in asymmetric synthesis, while …
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Palladium- and nickel-catalyzed C-N cross-coupling reactions featuring soluble organic bases
… the low intrinsic acidity of amines, palladium-catalyzed C-N cross-coupling plagued continuously by the necessity to employ strong, inorganic, or insoluble bases. To surmount the many Due to the low intrinsic acidity of amines, palladium-catalyzed C-N crosscoupling has been practical obstacles …
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Rhodium-Catalyzed Enantioselective Desymmetrizations of Oxabicyclic Alkenes and Alkene Difunctionalization via Nickel-Catalyzed Arylcyanation
… 1 of this thesis describes the development of a nickel-catalyzed arylcyanation reaction for the synthesis of 3,3-disubstituted oxindoles. This method was inspired by our work on the palladium-catalyzed arylcyanation reaction, originally developed to address challenges in the formal synthesis of …
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Nickel-catalyzed reductive coupling reactions of 1,6-enynes and the total synthesis of (+)-acutiphycin
Nickel-Catalyzed Reductive Coupling Reactions of Aldehydes and Chiral 1,6-Enynes. A study of nickel-catalyzed reductive coupling reactions of aldehydes and chiral 1,6-enynes has provided evidence for stereospecific ligand substitution from a planar three-coordinate nickel species as a plausible …
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Progress in nucleophilic catalysis and development of nickel-catalyzed cross-couplings of propargylic halides
… 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 enantioselective variant of this reaction is described. Chapter 2 discusses …
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Cross Coupling of Alkenyl Gold Complexes with Alkyl Electrophiles and Nickel Catalyzed Hydroarylation of Alkenes
… reactivity. The second reaction described is a nickel catalyzed hydroarylation of alkenes. We are able to achieve good anti-Markovnikov selectivity with a wide range of alkenes, including styrenes, alkyl substituted alkenes, and enol ethers.
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Nickel-catalyzed reductive coupling reactions : application to the total syntheses of pumiliotoxins 209F and 251D
… Coupling of 1,3-Enynes and Aromatic Aldehydes Nickel-catalyzed reductive coupling reactions of 1,3-enynes and aromatic aldehydes efficiently afford conjugated dienols in excellent regioselectivity and modest enantioselectivity. These reactions were conducted in the presence of a catalytic …
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Nickel-catalyzed preparation of acrylamides from alpha olefins and isocyanates ; Synthetic studies toward ripostatin A
… of the N-heterocyclic carbene ligand IPr, the nickel(0)-catalyzed coupling reaction of a-olefins and branched aliphatic isocyanates provides c,-unsaturated amides arising from preferential C-C bond formation at the 2-position of the olefin. This sense of regioselectivity contrasts with the …
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Asymmetric nickel-catalyzed three-component assembly of allylic amines from alkynes, imines and organoboron reagents
… carbon-carbon bond forming events. Even though nickel- catalyzed multi-component coupling reactions involving additions to carbonyl compounds have been reported, the process described herein is the first such example involving imines and also the first that utilizes boronic acids. [Image] ... An …
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Nickel-catalyzed coupling reactions and synthetic studies toward ent-dioxepandehydrothyrsiferol via an epoxide-opening cascade
Nickel-Catalyzed Coupling Reactions. Nickel-catalyzed allene--aldehyde coupling and alkene--aldehyde coupling represent two methods of preparing allylic alcohols. Most asymmetric transition metal-catalyzed methods of preparing enantiomerically enriched allylic alcohols rely on chiral ligands. The …
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Developments in Nickel-catalyzed Transfer Hydrocyanation Reactions and Novel Skeletal Editing Strategies through Nitrogen Atom Insertion
… of highly hazardous HCN. Herein, a focus on nickel- and Lewis acid-co-catalyzed transfer hydrocyanation using isovaleronitrile or butyronitrile as sacrificial HCN donor reagents is discussed (see Scheme I). Further developments allowed to circumvent the use of air- and temperature-sensitive …
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Nickel-catalyzed asymmetric cross-couplings of secondary allylic chlorides and planar-chiral compounds in asymmetric synthesis
In Part I, nickel-catalyzed asymmetric carbon-carbon bond-forming reactions are described. A nickel/Pybox system effectively catalyzes regio- and enantioselective cross-couplings between racemic secondary allylic chlorides and readily available alkylzinc halides. This method is applied to generate …
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Nickel-catalyzed asymmetric arylations of [alpha]-halocarbonyl compounds and studies of boratabenzene-containing transition metal complexes
… Negishi arylation of a-bromoketones using a nickel/pybox catalyst. The third section details the development of a Suzuki arylation of a-bromo- and a-chloroamides using aryl-(9-BBN) reagents. Both of these cross-coupling procedures are stereoconvergent, as they convert the racemic starting …
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Nickel-catalyzed asymmetric cross-couplings of secondary alkyl electrophiles and photoinduced, copper-catalyzed C-N couplings
Chapter 1 describes the development of three nickel-catalyzed asymmetric Negishi cross-couplings of secondary alkyl electrophiles via a stereoconvergent process. In Section 1.1, asymmetric Negishi arylations and alkenylations of [alpha]-bromonitriles with arylzinc and alkenylzinc reagents are …
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Diastereoselective nickel-catalyzed reductive coupling of alkynes and aldehydes and application towards the B-type amphidinolides
… of recently developed stereoselective nickel-catalyzed reductive coupling reactions of alkynes and aldehydes to the synthesis of complex natural product targets was explored. The "B-Type" amphidinolides were selected as ideal targets owing to their molecular complexity and the paucity …
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The nickel-catalyzed Mizoroki-Heck reaction : high regioselectivity in Olefin migratory insertion and photoredox-enabled indoline formation
… has been a longstanding challenge. Using a nickel-catalyzed cationic Heck reaction, we were able to achieve excellent selectivity for branched products (>/=19:1 in all cases) over a wide range of aryl electrophiles and aliphatic olefins. A bidentate ligand with a suitable bite angle and …
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Enantioselective nickel-catalyzed reductive coupling reactions of alkynes and aldehydes. Synthesis of amphidinolides T1 and T4 via catalytic, stereoselective macrocyclizations
I. Enantioselective Nickel-Catalyzed Reductive Couplings of Alkynes and Aldehydes Allylic alcohol synthesis via a nickel-catalyzed reductive coupling reaction of alkylsubstituted alkynes and aldehydes was studied for ligand effects with respect to the regioselectivity and enantioselectivity of the …
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Nickel-catalyzed cross-couplings of unactivated secondary and tertiary alkyl halides and photoinduced copper-mediated asymmetric C-N cross-couplings
Chapter 1 describes the development of two nickel-catalyzed Suzuki cross-coupling methodologies that employ alkyl halides as electrophiles. In Section 1.1, asymmetric [gamma]-alkylation relative to a carbonyl group is achieved via the stereoconvergent cross-coupling of racemic secondary …
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