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Showing 1 to 20 of 43 for “"Borylation"”.
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Development of Novel, Regioselective Borylation Protocols
… significant interest in the development of novel borylation protocols, especially those whose products are suitable for further synthetic transformations towards valuable classes of compounds. Research in organoboron synthesis has been geared heavily toward transition metal-catalyzed addition to …
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Developing and Understanding Iridium-Catalysed Arene Borylation
Iridium catalysed C-H borylation has moved from an interesting observation to an efficient catalytic reaction. This work has developed and improved upon some of the key issues associated with the methodology. The one-pot conversion of aryl boronates, generated by C-H borylation, to other …
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Studies in Selective C-C Bond Formation via Borylation and Dehydrogenation
Three stories of C-C bond formation are presented. First, we attempt to harness the Lewis acidity of boron to induce chemo- and regioselectivity in two fundamental organic reactions (Chapter 1). We explore 1,2-difunctionalization of alkenes via formation of a three-membered cyclic intermediate with …
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Regio- and Stereo- selective Methods for the Borylation of Substituted Alkynes
Organoboron derivatives represent an important class of compounds due to the versatility of the carbon-boron bond in a variety of chemical reactions. Boron-containing compounds have garnered increasing attention as synthetic intermediates and medicinal agents. Therefore, the introduction of …
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Bipyridine Ligands for use in Polymer-Supported Iridium Catalyzed C-H Borylation
… precatalyst afford a highly efficient C-H borylation, but studies of polymer-supported bipyridine ligands have not been extensively researched. With an aim to exploring this approach to allow recycling of the expensive iridium catalysts synthesis of new bipyridine ligands were undertaken. A …
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Application of Iridium-Catalysed C–H Borylation to the Functionalisation of Indoles
… novel applications of the iridium-catalysed C–H borylation of indoles. Research commenced with the development of a general procedure for the conversion of indoles 242 to 7-hydroxyindoles 245 and indolequinones 243. This was achieved by a three-step procedure – an initial C7–H borylation was …
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CATALYTIC BORYLATION OF C-H BONDS: A ROUTE TO PHOTOPHYSICALLY INTERESTING PYRENE DERIVATIVES
… properties. Using the regiospecific direct C-H borylation of pyrene with an Ir-based catalyst, prepared in situ via reaction of [Ir(OMe)COD]2 with 4,4’-di-tert-butyl-2,2’-bipyridine, 2,7-bis(Bpin)pyrene 1 and 2-(Bpin)pyrene 2 (pin = OCMe2CMe2O) were synthesized. Straightforward derivatization …
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Iridium-catalyzed borylation of aromatic and aliphatic C-H bonds: methodology and mechanism
… cyanation of arenes by iridium-catalyzed C-H borylation and copper-mediated cyanation of the resulting arylboronate esters is described in Chapter 2. This process relies on a previously unknown method to conduct the cyanation of arylboronic esters, and conditions for this new transformation …
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Development of Transition Metal-Catalyzed Borylation Protocols using Symmetrical and Unsymmetrical Diboron Reagents
… operationally simple transition metal-catalyzed borylation protocols with alkynes and diboron reagents. An open-to-air copper(II)-catalyzed aqueous borylation protocol of alkynoates and a symmetrical diboron reagent is reported. Conjugate addition of the boryl-copper species to the electrophilic …
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Controlling the Regio- and Enantioselectivity of Iridium-Catalysed Arene Borylation Using Sulfonated Bipyridine Ligands
… enantioselectivity of iridium-catalysed arene borylation, an incredibly synthetically useful transformation that commonly suffers from a lack of regioselectivity, and for which enantioselective variants are very few. The strategy followed involved the design and synthesis of novel bipyridine …
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A hydrogen bonding ortho-directing effect for the iridium catalyzed borylation of NH(t-BOC) aromatics
The C-H borylation of aromatic substrates has evolved from a stoichiometric curiosity to a valuable methodology for the synthetic chemist. Understandings of regioselective activation and high functional group tolerance have been considerably praised. Most aromatic substituents, such as alkyl, …
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An Exploration of Ion Pairing Interactions as a Tool to Control Regioselectivity in Iridium-Catalysed C–H Borylation
… and para selectivity in iridium catalysed C–H borylation. An ion pairing interaction between a functionalised ligand and matching functionality on a substrate was initially explored for achieving meta C–H selectivity. By using an anionic sulfonate group on the ligand and cationic quaternary …
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Iridium Catalysed Borylation as a Platform for Exploring the Use of Non-Covalent Interactions to Control Regio- and Enantioselectivity
… and step-economic fashion. Iridium catalysed borylation of arenes is a powerful yet mild C-H activation transformation which yields synthetically useful boronate esters. Interestingly the selectivity of this reaction is largely based upon steric considerations. As a result, the process is …
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Synthetic Retinoids
… forming reactions and transition metal-catalysed borylation of aromatic and vinylic C-H bonds, respectively. Chapter two details the application of sequential Ir-catalysed aromatic C-H borylations, Pd-catalysed C-C bond forming reactions and Rh-catalysed vinylic C-H borylations for the …
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New methodologies and approaches to reaction discovery in transition metal catalysis
… have been developed based upon iridium-catalyzed borylation of aromatic and heteroaromatic C-H bonds. A general, one-pot method for alkylation of arenes with the site-selectivity controlled by steric effects as opposed to electronic effects via Ir-catalyzed C-H borylation followed by Pd- or …
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Development of Ion Pairing Strategies that Utilise Cations to Control Selectivity in Transition Metal-Catalysed Functionalisation of C–H Bonds
… Chapter 2 focusses on the iridium-catalysed borylation of aromatic C(sp2)–H bonds. The lack of regiocontrol for 1,2-disubstituted arenes under standard conditions has previously been addressed by introducing an ion pairing interaction between a cationic substrate and an anionic ligand to …
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Fused Heterocycles as Spinster Homolog 2 Inhibitors and Regio- and Stereoselective Copper-Catalyzed Borylation-Protodeboronation of 1,3-Diynes: Access to (Z)-1,3-Enynes
Sphingosine 1-phosphate (S1P) is a lipid chemoattractant molecule. Once formed, S1P can be transported extracellularly by S1P transporters spinster homolog 2 (Spns2) or major facilitator domain containing 2B (mfsd2b). In the extracellular space, S1P can bind to S1P-specific G-protein coupled …
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The Application of Catalysis based on Hydrogen Bonding and Ion-pairing Interactions to Asymmetric Minisci-type Alkylations of Azines and Iridium-Catalysed C-H Borylation.
… to meta-selective iridium-catalysed C-H borylation. Although there are a several reports of enantioselective ortho-selective borylation of arenes, a reaction that reached more remote positions had not yet been realised. The association of a chiral countercation with an anionic sulfonated …
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Metal-Catalyzed Formation and Transformations of Carbon-Boron Bonds
… myriad of unsaturated substrates for conducting borylation reactions, allenes have received minimal attention. These substrates are uniquely advantageous given that diboration results in the formation of both allylic and vinylic boronates. Orthogonal reactivity of the sp2 and the sp3 C-B bonds …
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Boron-Mediated Semireduction of Alkynoic Acid Derivatives
… several methods that achieve the trans-selective borylation or semireduction of internal alkynes, a process dominated by transition metals and often results in incomplete (E)-stereoselectivity. This dissertation describes three novel uses of a diboron reagent or pinacolborane that reduce propiolic …
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