Global ETD Search
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Showing 1 to 20 of 150 for “"Electron-rich"”.
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Interactions of Nitrated Aromatics With Electron Rich Species: Chiral and Achiral
The work described in Chapter 6 is of a mechanistic nature. Identification of the formation of Meisenheimer complexes under conditions of phase transfer catalysis helped to rationalize the enantioselectivity observed in these systems. Quaternary ammonium cations are identified as stabilizing …
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Triplex Diels-Alder reactions of beta-methylstyrenes. Density functional investigation of pion-pion interactions
The (4+2) cycloaddition of an electron-rich diene to an electron-rich dienophile may be catalyzed by irradiation of a cyanoarene. This reaction is shown to proceed through an intermediate ternary excited state complex (triplex) and is therefore called the triplex Diels-Alder reaction. Evidence is …
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Studies in palladium and rhodium catalysis: synthetic strategies for C–C bond formation
… medicinal and natural products. Many contain electron-rich aryl rings. Previously, we found that the wellestablished conditions, which promote C−H functionalisation through Concerted MetalationDeprotonation (CMD), proved unsatisfactory for electron-rich diarylether precursors. Herein, we …
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The development of palladium-catalyzed cross-coupling reactions of allylic silanolate salts with aromatic bromides
… 73–95% yields of the allylation products. Both electron-rich and sterically hindered bromides reacted smoothly, whereas electron-poor bromides cross-coupled in poor yield because of a secondary isomerization to the 1-propeneyl isomer (or concommitant polymerization). A modified protocol that …
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Expanding the substrate scope in palladium-catalyzed C-N and C-C bond-forming reactions
… of aryl nonaflates is reported. Use of bulky electron-rich monophosphinobiaryl ligands or BINAP allow for the catalytic amination of electron-rich and -neutral aryl nonaflates with both primary and secondary amines. Using XantPhos, the catalytic amination of a variety of functionalized aryl …
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Investigation of Factors Influencing Recombination Versus Disproportionation of Complex Radicals Formed by C-N Homolysis of Breslow Type Intermediates and Related Compounds
<p>Electron rich enamines are capable of C-N bond homolysis and subsequent recombination and/or disproportionation. It is unclear what causes these radicals to undergo recombination or disproportionation. Density Functional Theory (DFT) calculations do not provide a transition state for the …
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The synthesis and applications of a biaryl-based asymmetric phosphine ligand
… of hindered boronic acids with the electron-rich aryl bromide, 1-bromo-2- methoxynaphthalene, to synthesize biaryls in modest enantioselectivity.
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Synthesis and application of sterically flexible and water-soluble phosphine ligands in palladium catalysis
… with the study of the influence of flexible, electron-rich phosphine substituents such as the neopentyl and benzyl groups on catalyst activity, particularly for the Suzuki coupling of sterically hindered substrates. I have also synthesized two new water-soluble phosphine ligands that utilize …
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Acetylene Functionalized Photocatalytic COFs for PFAS Adsorption and Degradation
… The challenge is designing COFs that include electron-rich rings with a suitable pore size to absorb and degrade the contaminants. Herein, we demonstrate the novel synthesis of a series of COFs or amorphous porous organic polymers (APOP) with delocalized π-conjugated systems, followed by …
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The palladium-catalyzed synthesis of organic amines
… involving a variety of substrates, including electron-poor anilines or electron-rich aryl bromides. In addition, it tolerates a high degree of steric congestion at both the aniline and the aryl bromide.
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Underutilized Dineophiles: Asymmetric Diels-Alder Reaction of Ynones and Ynoates with Oxygen-Functionalized Dienes
… and ynoates (Figure A1).The proposal is to use electron-rich dienes, similar to Danishefsky's diene, in order to generate 1,4-cyclohexadienes that have functional groups that can take part in further chemoselective transformations. The ability to construct six-membered rings with distinct …
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The formation of cyanoborate liquid clathrates with water or cresol as promoters
… on liquid clathrates was proposed. The II electron rich nature of the guest is important in the model, so the guests, furan, thiophene and benzene, were used to probe the dependence of cyanoborate liquid clathrate formation on the IT electron rich nature of the guest. Differences in the …
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Simplified Synthesis of Conjugated Polymers Enabled via 1,4-Dihydropyrrolo[3,2-b]pyrrole
… as the active layer material in organic electronics, such as organic photovoltaics and light-emitting diodes, partly due to the ability to influence a broad range of properties through structural design motifs. However, high performance conjugated polymers suffer from numerous synthetic …
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Metal catalyzed generation of reactive benzomethane intermediates for the synthesis of benzopyrans, tetrahydroquinolines and chiral aryl methanes
… of the reaction. The reaction is tolerant of electron-rich phenols, aromatic, aliphatic, and heterocyclic aldehydes and electron-rich olefins. The synthesis of Psiguajadial F demonstrates the utility of the two-component methodology of o-hydroxybenzyl alcohols and olefins. Psiguajadial F is a …
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Carbon-Carbon Bonds Formed by Lewis Acid Catalysis or Photoactivation
… a mild Friedel-Crafts reaction between electron-rich aromatics and allylic or benzylic alcohols. Moreover, these methods can be applied to the synthesis of natural products. Finally, photoactivation of tosylhydrazones can allow for C–C bond formation when paired with organoboronates. …
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Structural and Functional Models of the Iron -Only Hydrogenase Enzymes
… state of the H-cluster were synthesized. Electron-rich polyisocyano compounds Fe2(S 2CnH2n)(CO)2(CNMe)4 undergo oxidatively induced reaction with additional CNMe to give [Fe2(S2CnH 2n)(CNMe)7](PF6)2, the first members of a new class of iron thiolates. Crystallographic characterization …
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Part One: Radical Cation and Triplex Diels-Alder Reactions. Part Two: Photochemistry of Tri-1-Naphthylboron
Part One. The Diels-Alder reactions of electron-rich alkenes and alkadienes in a photochemical electron transfer system are presented. In acetonitrile, the Diels-Alder dimerization of 1,3-cyclohexadiene (1) is shown to be the result of the reaction of the radical cation of 1. A chain mechanism and …
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JULIA-KOCIENSKI APPROACH TO 4-SUBSTITUTED 1- ALKENYL-1H-1,2,3-TRIAZOLES
… Julia-Kocienski olefinations proceeded with electron-rich and electron-deficient aryl, as well as alkyl aldehydes. The resulting 1,2-disubstituted alkenes were formed in good yields, but with moderate to poor E/Z-selectivities. A modular approach to the synthesis of 4-substituted …
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Synthesis and Application of Tunable Mo2 and W2 Tetraguanidinate Paddlewheel Complexes
Super-electron-donor dimolybdenum and ditungsten tetraguanidinate paddlewheel complexes have proven to be the strongest reducing agents known. Strong single and double electron donors can be used for applications from H2 production to difficult organic transformations like C–Cl bond cleavage and …
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The synthesis and use of cyclic nitronic esters
… by conducting a Hammett study which showed that electron-rich nitrostyrenes cyclize the fastest. It was shown that nitroalkenes can behave as the diene component of the cycloaddition with cyclic dienes due to the effect of the Lewis acid. Finally, the selectivity of the intramolecular …
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