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.
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Showing 1 to 15 of 15 for “"enantioselective catalysis"”.
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Progress in transition metal-based enantioselective catalysis
In Chapter 1, the first enantioselective cross-coupling reactions of racemic secondary benzylic halides are described (eq 1). This method was applied to the syntheses of intermediates employed by other groups in the generation of bioactive compounds, e.g., an androgen receptor agonist (1.1) and two …
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Enantioselective catalysis using heterogeneous and dissymmetric salen complexes of Mn and Cr
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1999.
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Prediction of higher selectivity catalysts by a computer driven workflow and machine learning and computational investigation of boronate esters in the Suzuki-Miyaura cross coupling
… a comprehensive overview of chemoinformatics in enantioselective catalysis. Chapter two is comprised of completely unpublished work detailing the synthesis of a diverse set of bisoxazoline ligands in the planned optimization of an enantioselective aziridination reaction. Although this work was …
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Asymmetric Catalysis with Brønsted Acids: Experiments and Calculations
The research described herein focuses on enantioselective catalysis using BINOL-based Brønsted acids. The initial part of this work comprises the development of chiral phosphoric acids and N-triflylphosphoramides having alternative groups at the 3,3’- positions, different from the widely common …
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Diversity oriented, computer guided catalyst design: Application of chemoinformatics to catalysis
… developed for the workflow towards problems in enantioselective catalysis. The second half of this thesis (Chapter 4) focuses on the use of chemoinformatics to develop design criteria for active phase-transfer catalysts. The most common parameter used to predict PTC rates, the ammonium ion …
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An Exploration of Ion Pairing Interactions as a Tool to Control Regioselectivity in Iridium-Catalysed C–H Borylation
… recently started being used in small molecule catalysis for control of selectivity. To date, this has been particularly fruitful in the area of enantioselective catalysis when using ion pairing or hydrogen bonding. Despite the success seen by ion pairing in enantioselective organocatalysis, …
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Modifications to the Suzuki reaction and mechanistic insights on the NBS mediated cleavage of benzylidene acetals /
One of the most challenging tasks for a synthetic organic chemist today, is the development of chemo, regio, and stereoselective methodologies toward the total synthesis of macromolecules. r . The objective of my thesis was to develop methodologies towards this end. The first part of my project was …
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New Catalysts for Asymmetric Nitrene Transfer Based on Ion-Pairing Between Sulfonated Rhodium(II,II) Tetracarboxylates and Chiral Cations: Design, Synthesis and Applications to Enantioselective Carbon-Nitrogen Bond Formation
… Cations: Design, Synthesis and Applications to Enantioselective Carbon-Nitrogen Bond Formation – Alexander Fanourakis The work presented in this thesis investigates a new strategy for the catalytic, asymmetric synthesis of C(sp3)–N bonds and is divided into three parts. First, the design and …
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Design and Application of Transition Metal Complexes for Catalysis
… properties can be extended to a design of highly enantioselective peptide catalysts. The designed peptides comprised of as few as two amino acid residues spontaneously self-assemble in the presence of metal ions to form supramolecular, vesicle-like nanoassemblies that promote the transfer …
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Enantioselective (Formal) Aza-Diels-Alder Reactions with Danishefsky's Diene and Non-Danishefsky Type Dienes
… agents. As a direct result, efforts to develop enantioselective diene-imine (aza-Diels-Alder) reactions to efficiently access these substructures have increased. We have developed highly enantioselective silicon Lewis acid mediated formal aza-Diels-Alder reactions with Danishefsky's diene and …
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Synthesis of Chiral Benzimidazolylidenes from 1,10-Phenathrolines and 1,10-Phenathroline-2,9-dione /
A^-heterocyclic carbenes (NHCs) have become the focus of much interest as ancillary ligands for transition metal catalysts in recent years. Their structural variability and strong cy-donation properties have led to the preparation of demonstrably useful organometallic catalysts. Among the three …
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Lewis base catalyzed enantioselective sulfenoamination of alkenes
… 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 selenophosphoramide, in presence of a Brønsted …
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Density Functional Theory: Development and Applications
… (Chapters 3 and 5) and the effect of mutation on catalysis of enzymes (Chapter 4). We then extend upon a previously developed DFT functional, making it applicable to both the treatment of barrier heights and transition states (Chapter 7) and then proceed to make it continuous and capable of …
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Asymmetric cyclopropanation via catalysts incorporating the 1,4-diol ligands and the newly designed dioxaborolane /
… suggest that they are the potential catalytic enantioselective candidates to build C-C bonds.
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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
… 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, enantioselective …