Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 73 for “"Lewis-acids"”.
-
Formation and capture of thiiranium ion intermediates using Lewis acids
Submission published under a 24 month embargo labeled 'U of I only', the embargo will last until 2017-08-01
-
Thermodynamics of Molecular Addition Compound Formation Between Amides and Lewis Acids
Made available in DSpace on 2014-12-05T19:37:48Z (GMT). No. of bitstreams: 1 6104402.pdf: 2471219 bytes, checksum: 7150fa5f304da913bf0ee9390f8bc520 (MD5) Previous issue date: 1961
-
Reactions at coordinated ligands: redox-active ligands and coordination of Lewis acids
… of redox-active ligands, ligand protonation and Lewis acid coordination to ligands. The focus is on ligand design rather than substrate or metal optimization with a primary interest in reactivity with dihydrogen. The main thrust of the work has been the investigation of redox-active ligands in …
-
Lewis Base Activation of Lewis Acids in Asymmetric Aldol Reactions of Silyl Ketene Acetals
The concept of Lewis base activation of Lewis acids has been effectively reduced to practice for catalysis in the chiral phosphoramide catalyzed/SiCl 4 promoted aldol reaction of silyl ketene acetals and silyl dienol ethers with aldehydes. The weakly acidic species, silicon tetrachloride (SiCl 4), …
-
New Approaches Towards the Asymmetric Allylation of the Formyl and Imino Groups via Strained Silane Lewis Acids
… functionalities by using strained silanes as Lewis acids. Here in the Laboratory of Professor James L. Leighton, chiral homoallylic alcohols and amines are considered privileged products given their important role as building blocks in natural product synthesis. The new approaches reported …
-
Synthetic and mechanistic investigation of new radical processes: reaction of organic azides with group-XIII Lewis acids
… with indium trichloride and other group XIII Lewis acids, in particular gallium trichloride, gives rise to strongly coloured, persistent paramagnetic species, whose structure is consistent with the radical cation of the head-to-tail dimer of the aniline corresponding to the starting azide.
-
Boron Subnaphthalocyanines: The First Unsubstituted Examples, New Boron Lewis Acids, Random Bay Position Halogenation, and Computational Material Screening
… this, we proposed that a non-halide boron based Lewis acid is required, and that a balance of the Lewis acidity of the boron source and the Lewis basicity of the BsubNc precursor can guide the synthesis of BsubNcs. After achieving this desired outcome, we also explored the application of this …
-
Applications of novel boron-nitrogen containing heterocycles : design and synthesis o planar-chiral Lewis acids for stereoselective organic synthesis
Because Lewis acids are very versatile mediators of a variety of stereoselective organic transformations, a great deal of effort has been devoted toward the development of chiral Lewis acids. This thesis describes the design, synthesis, and applications of 1,2-azaborolyl complexes as a novel family …
-
Synthesis and catalytic structure activity relations of hydrophobic zeolites with isolated framework metals that act as water tolerant Lewis acids
… hydrophobic zeolites results in water-tolerant Lewis acids. This thesis discusses the synthesis, characterization, and structure-activity relations of metal-substituted Beta zeolites in the conversion of oxygenates. Chapter 2 discusses the application of dynamic nuclear polarization (DNP) NMR to …
-
Scope, Selectivity, and Mechanism of the Prins Cyclization of Delta,&egr;- and &egr;,zeta-Unsaturated Ketones With Lewis Acids to 1,3-Halohydrins
Finally, reduction in R:FR increased vertical growth and erectness of both BAS1 gene transformants and control plants, however, overexpression of BAS1 gene induced dwarfism in transgenic creeping bentgrass by delaying vertical shoot growth and altering shoot architecture. True BAS1 transformants …
-
Stereochemical Course of the Tandem [4+2]/[3+2] Cycloaddition of Nitroalkenes
… and theoretical studies. Small, soft Lewis acids (such as Me 3Al) promote endo cycloaddition with the vinyl ether reacting in an s-trans conformation. Most other Lewis acids favor exo cycloaddition due either to their size (such as MAPh) or the conformation they force upon the …
-
Spectroscopic Studies on Lewis Acid-Base Interactions. Part One: Epr Studies of Lewis Acids and Bases Interaction. Part Two: Kinetic Studiesof Chemical Reactions by Calculation of Exchange-Broadened Nmr-Lineshapes
Made available in DSpace on 2014-12-10T23:01:30Z (GMT). No. of bitstreams: 1 7317152.pdf: 2532411 bytes, checksum: 053b8ca1ee02f9e43f6a90fbb46f717d (MD5) Previous issue date: 1972
-
Carbon-Carbon Bonds Formed by Lewis Acid Catalysis or Photoactivation
… from propargylic alcohols, organoboronates, and Lewis acids. Lewis acids can also be used to facilitate 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, …
-
A Lewis Acidic Stroll Through the p-Block
Since the inception of frustrated Lewis pair (FLP) chemistry more than a decade ago, the development of an assortment of main group Lewis acids in the literature has contributed to the enrichment and diversification of FLP reactivity to achieve transition metal-like chemistry. While most of the …
-
Synthesis and reactivity of early transition metal "Frustrated Lewis Pairs"
… introduced the new concept of "Frustrated Lewis Pairs" (FLP) wherein sterically demanding Lewis acids and bases do not interact in the expected donor-acceptor fashion, but rather exhibit unique reactivity. To date this concept of FLPs has been limited to main group systems. In this thesis …
-
Part I. Stereochemical Studies on the Addition of Allylsilanes to Aldehydes. Part II. Stereochemical Studies on the Addition of Allylmetal Reagents to Acetals
… performed to determine the solution structure of Lewis acid-aldehyde complexes. The intramolecular allylmetal-aldehyde reaction was next studied using three different model systems. The first two model systems were investigated to determine the relative disposition of double bonds in the …
-
Chiral-Phosphoramide-Catalyzed Enantioselective Allylation Reactions: Mechanistic, Structural and Preparative Studies
The method of generating chiral Lewis acids with a combination of SiCl 4 and chiral phosphoramides has been applied in the formal hetero-Diels-Alder reaction and modest to high selectivities have been obtained.
-
Probing the Impact of Solvent on Lewis Acid Catalysis via Fluorescent Lewis Adducts
… have been developed to measure the strength of a Lewis acid. However, a major challenge for these measurements lies in the complexity that arises from variables, such as solvent and other fundamental interactions, as well as perturbations of Lewis acids as their reaction environment changes. …
-
Asymmetric synthesis of novel anthracyclinones
… of novel C9-halogenated anthracyclinones by Lewis acid promoted cyclisations of ortho-methallyl anthraquinonyl chiral dioxanes has been investigated. Tin tetrachloride-N,N-dimethylformamide promoted cyclisation of the dioxane (30) proceeded with excellent stereoselectivity to give an 82% …
-
Retro-Diels-Alder routes to 4,5 disubstituted cyclopentenones
… tricyclodecadienones using several Lewis-acid catalysts. 4-Substituted-2 cyclopentenones were isolated in good yield and no double bond rearrangement or decomposition was observed. Similar results were also obtained with the dienones generated from dehydration of β-ketols to give …
Page 1 of 4