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Showing 1 to 20 of 70 for “"Lewis base"”.
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Lewis base catalyzed enantioselective oxysulfenylation of alkenes
The Lewis base activation of Lewis acids has been harnessed in the development of an enantioselective oxysulfenylation reaction for unactivated alkenes. The weak Lewis acid N-(phenylthio)-phthalimide can be activated in the presence of a moderate Brønsted acid and chiral Lewis base donors. The …
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Lewis base catalyzed enantioselective sulfenoamination of alkenes
The concept of Lewis base activation of Lewis acid has been successfully applied to the enantioselective sulfenoamination of olefins. The unreactive, achiral Lewis acidic sulfenylating agent, N-arylthiophthalimide, is activated by the coordination of a chiral Lewis base, binaphthyl-derived …
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Development of a Lewis Base Catalyzed Selenocyclization Reaction
"A variety of chiral, ""soft"" Lewis base donors were prepared and tested in the selenofunctionalization reaction. An enantioselective process was never realized. Mechanistic investigations have revealed that the seleniranium ion intermediate (which is formed after delivery of the electrophilic …
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Lewis Base Promoted Annulations of Allenoates with 1,4-Naphthoquinones
<p>Lewis base promoted cyclization of allenoates with electron deficient olefins open up the possibility to generate more complex organic structures. By generating more complex molecules, we are able to produce new compounds for biomedical and material applications. Both phosphine and amine Lewis …
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Lewis Base-Catalyzed Enantioselective Allylation and Aldol Addition Reactions
Embargo set by: Seth Robbins for item 85720 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs
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Lewis Base Catalyzed Enantioselective Aldol Additions: Preparative and Mechanistic Studies
Kinetic studies using ReactIR and rapid injection NMR (RINMR) spectroscopy have confirmed the existence of dual mechanistic pathways involving either one or two phosphoramides. Determination of Arrhenius activation parameters revealed that aldol addition occurs through the reversible albeit …
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Asymmetric Lewis base catalysis: I. Lewis base catalyzed halogenation and development of an enantioselective bromocycloetherification reaction; II. enantioselective addition of silyl ketene imines to carbonyl electrophiles
Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2012-06-15T13:39:00Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 2 Thesis-6-12.docx: 11084823 bytes, checksum: 0609048b408ae3adf1f485e3a9dde5d3 (MD5) Burk_Matthew.pdf: 14255171 bytes, …
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Development of a Lewis base catalyzed, sulfenium-ion initiated enantioselective, spiroketalization cascade
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2022-04-06 without embargo terms
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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
… good overall yield. Last, proof of principle for Lewis base activation of acids in reactions of silyl ynol ethers with aldehydes has successfully demonstrated. Particularly, the phosphoramide/SiCl4 system has been shown to function as a catalyst in these reactions. More importantly, experimental …
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Lewis-base Thioacetamide assisted crystallization of lead-free perovskite solar Cells for improved Efficiency
… mobility and the theoretical efficiency of Sn-based perovskites reaching approximately 30% due to their optimal smaller bandgap between 1.1 and 1.4 eV. Due to similar ionic radii and outermost electron configuration to Pb2+, Sn-based PSCs have been a magnet for significant rearrangement in the …
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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), …
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Synthesis, study and application of silyl ketene imines in Lewis base catalyzed carbonyl addition
The activation of Lewis acids by chiral Lewis bases has allowed for the development of a robust and highly selective catalyst system for the addition of silylated nucleophiles to carbonyl compounds. In general, aldolate-type products containing secondary and tertiary stereogenic centers are …
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Lewis Base Catalyzed Aldol Additions of Chiral Silyl Enol Ethers and Total Synthesis of Rk-397
The double diastereodifferentiation in chiral Lewis base catalyzed aldol additions was examined using chiral silyl enol ethers derived from hydroxyisobutyrate and hydroxybutyrate. Trichlorosilyl enolates derived from the chiral methyl and ethyl ketones were subjected to the Lewis base catalyzed …
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Studies in Asymmetric Catalysis: Lewis Base catalyzed/Lewis Acid Mediated Aldol Reactions of Ketone- and Amide Derived Nucleophiles
Additionally, the use of the silicon tetrachloride---chiral phosphoramide system has proven a competent catalyst for highly selective vinylogous aldol reactions between dienolates derived from a variety of alpha,beta-unsaturated carbonyl compounds to aldehydes. These reactions provided high levels …
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Enantioselective alkene difunctionalization enabled by organochalcogen catalysis I. Lewis base-catalyzed sulfenium ion transfer II. Organoselenium redox catalysis
Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2025-05-01
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Studies in Asymmetric Catalysis. Part I. Lewis Base-Catalyzed Aldol Additions. Part II. Bis(oxazoline)palladium(ii)-Catalyzed Cyclopropanation
A variety of bis(oxazoline)palladium(II) complexes were prepared and tested in the cyclopropanation of ethyl (E)-cinnamate with diazomethane. Although an enantioselective process was never realized, effects of substitution on the ligand, catalyst loading studies, and other investigations led to a …
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Studies in Asymmetric Catalysis: Lewis Base Catalyzed, Enantioselective Addition of Trimethylsilyl Cyanide, Trimethylsilyltrifluoromethane, and Glycolate-Derived Silyl Ketene Acetals to Aldehydes
… involving silicon tetrachloride and a chiral, Lewis basic bisphosphoramide catalyst is effective for the addition of glycolate-derived silyl ketene acetals to aldehydes. The sense of diastereoselectivty could be modulated by changing the size of the substituents on the silyl ketene acetals. In …
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Enantioselective, Lewis base-catalyzed transformations: I. Polyene sulfenocyclization (preparative and mechanistic aspects) II. Sulfenofunctionalization of alkenyl boronates enabled by 1,2-boronate migration
… projects which are united under the umbrella of Lewis base catalysis. Following an overview of the key principles behind Lewis base catalysis and how it is used to enhance the electrophilicity of Lewis acids (Chapter 1), the bulk of this thesis will focus on the development of a catalytic, …
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A Study of Lewis Acid-Base Interactions: Part 1 - a Tin-119 Moessbauer and Tin-119 Nmr Study of the 1: 1 Lewis Base Adducts of Trimethyltin Chloride. Part 2 - a Calorimetric, and F(19), B(11), and H(1) Nmr Study of the Lewis Base Adducts of Boron-Trifluoride
Made available in DSpace on 2014-12-09T17:36:13Z (GMT). No. of bitstreams: 1 6910722.pdf: 5353101 bytes, checksum: 36aca5a579ee06afcbff0064c0a9f87d (MD5) Previous issue date: 1968
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Lewis Base Catalysis: I. Catalytic Enantioselective Aldol Additions of Methyl Trichlorosilyl Ketene Acetal to Ketones. II. Catalytic Enantioselective Alpha-Additions of Isocyanides to Aldehydes
The first catalytic, enantioselective alpha-addition reaction of isocyanides has been demonstrated with a SiCl4·bisbinaphthyldiamine phosphoramide catalyst. Good yields have been obtained with aromatic, heteroaromatic, conjugated non-aromatic and non-branched aliphatic aldehydes. Aromatic, …
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