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Showing 1 to 19 of 19 for “"C-H insertion"”.
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TEMPLATE DIRECTED C-H INSERTION REACTIONS FOR STEREOCONTROLLED SYNTHESIS OF HETEROCYCLES
Template Directed C-H Insertion Reactions for Stereocontrolled Synthesis of Heterocycles Orobosa Marvis Erhunmwunse, PhD. Non aromatic heterocycles and their analogues are abundant in a large variety of bioactive natural products and continue to play crucial roles in modern day chemotherapy. The …
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Catalyst and substrate effects in enantioselective C–H insertion reactions of α-diazosulfones
… The key reaction pathways explored were C–H insertion and cyclopropanation, with hydride transfer competing in certain instances. Significantly, up to 98% ee has been achieved in the C–H insertion processes using copper-NaBARF-bisoxazoline catalysts, with the presence of the additive NaBARF …
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Rhodium(II)-Stabilized Vinylcarbenes: Synthetic Applications in Ylide, Cyclopropanation, and C-H Insertion Reactions
… cyclopropanation and intermolecular C-H insertion reactions. The vinyldiazolactone derived from 5,6-dihydro-2H-pyran-2-one provided good enantioselectivities (>80% ee) in an intermolecular C-H insertion reaction with 1,4-cyclohexadiene and cyclopropanation reactions with styrene and …
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Synthetic and stereochemical aspects of enantioselective copper catalysed C-H insertion reactions leading to cyclopentanones and sultones
… copper–bis(oxazoline)–NaBARF catalysed C–H insertion reactions. Excellent enantioselectivities of up to 91% ee were achieved in the synthesis of cyclopentanones and up to 95% ee in the synthesis of sultones. Chapter One contains a comprehensive review providing an insight into the effect of …
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Investigation of catalyst effects in enantioselective copper- and rhodium-mediated transformations of α-diazocarbonyl compounds
… enantioselective C–H insertion reactions leading to enantioenriched cyclopentanone derivatives. Through the use of additives, the enantioselectivity achieved with the copper catalysts for the first time reaches synthetically useful levels (up to 91% ee). Chapter one …
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NEW TRANSITION METAL CATALYSTS FOR CARBON-CARBON BOND FORMATION
… complexes were successfully applied to the C-H insertion reaction of carbenes. This transformation facilitates the direct functionalization of alkanes without the need for an intermediate. This methodology holds the promise of more direct synthesis pathways and has drawn commensurate interest. …
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Studies on Syntheses of 1-Azaspirocycles, 2,6-Disubstituted 3-Piperidinols and cls-Decahydroquinolines
… The Rh(II)-catalyzed intramolecular tertiary C-H insertion reaction of 5-(-diazoacetoxy)piperidin-2-ones and 3-(-diazoacetoxy)pyrrolidines carrying C6 and C2 alkyl substituents, respectively, was investigated for the formation of bicyclic lactones bearing a nitrogen-substituted quaternary …
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Iron-catalyzed C—H alkylation and photoredox frontal ring opening metathesis polymerization
… of an iron catalyzed metallocarbene C—H insertion method is the subject of the first two chapters. Investigation of a photoinitiated frontal ring opening metathesis polymerization method comprises the last two chapters. Iron metallocarbenes are common intermediates in a wide range of …
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Studies toward Augmented Carbene/Alkyne Cascade Reactions and Ruthenium Catalysts for Propargylic Substition
… reaction goes through metal-carbene and alkyne insertion, and finally C-H insertion or alkyl migration. Because of ring-strain and steric effects, a cyclic syn-alkynyl diazoacetate approach underwent direct C-H insertion. A linear di-alkynyl diazoacetate approach underwent a gold-catalyzed …
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Studies towards the total synthesis of labiatin A
… transformations- intramolecular C-H insertion reaction and oxonium ylide formation followed by [2,3]-sigmatropic rearrangement- is presented. In Chapter II, the successful applications of these two reactions to the enantioselective synthesis of the tricyclic core of labiatin A is …
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Stereo–Chemical Control of Organic Reactions in the Interlamellar Region of Cation–Exchanged Clay Minerals
… addition (cyclopropane formation) and C-H insertion reactions (-lactam, -lactam and -lactone formation) catalysed by the Cu(II) exchanged clay minerals and the stereochemical consequences of carrying out the reactions within the clay interlayer
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Intramolecular [4+2] cycloadditions of conjugated ynones and related species ; Studies directed toward the total systhesis of glycinoeclepin A
… leading to a 3-furfuryl carbene. A 1,2-C-H insertion then produces the polycyclic furan product. A detailed analysis of the scope and mechanism of this reaction is presented. The synthetic utility of the method for the synthesis of complex organic molecules is illustrated by two sequences …
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Novel synthetic methodology employing transition metal catalysed reactions of α-diazo-β-keto sulfonamides and α-cyano-α-diazoacetates; the impact of substituents on the reaction pathway
… rhodium- and copper-catalysed intramolecular C–H insertion, the α-cyano-α-diazoacetates and α-arylsulfonyl-α-diazoacetates probed intramolecular aromatic addition. The precise impact of the substituents of an α-diazocarbonyl compound, on the ensuing rhodium- and copper-catalysed reaction …
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Synthesis of novel cycloperoxides
… Wittig chemistry and Lewis acid-catalysed C-H insertion strategies. The synthesis of a cis-γ,δ-unsaturated β-keto ester and a non-enolisable α,α-disubstituted β-keto ester are also outlined. The optimisation of the organocatalysed peroxidation of γ,δ-unsaturated β-keto esters in terms of …
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Design and use of novel metal catalysts in organic synthesis
… in intramolecular and intermolecular C-H insertion reactions, cyclopropanation and desymmetrisation reactions. The evolution of dirhodium carboxylate design since the 1980s is explored. This summary provides insight into their use as enantioselective catalysts in asymmetric transformations …
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A Matrix Isolation Spectroscopic Investigation Into the Reaction Products of Vanadium Metal Atoms With Propene
… matrix isolated product formed after metal atom insertion into the C-H bond of propene at low propene mole ratios is isolated and identified. The location of the insertion site is identified as one of the methyl hydrogen carbon bonds. The structure of the product is identified as an allyl …
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Development of base metal-catalyzed C—H functionalization reactions
… via a pathway that lies between concerted C—H insertion, observed with reactive noble metals (e.g. rhodium), and stepwise radical C—H abstraction/rebound, observed with chemoselective base metals (e.g. iron). Rather than achieving a blending of effects, [Mn(tBuPc)] aminates even 1° aliphatic …
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C(sp3)-H aminations under first row transition metal catalysis
… likely that rhodium’s concerted asynchronous C—H insertion mechanism, which favors functionalization at more electron-rich sites, is responsible for this lack of chemoselectivity. Conversely, first row transition metal catalysts like iron and manganese are thought to react through a stepwise …
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Cascade Transformations in Organic Synthesis: I. The Interception of Carbene Alkyne Metathesis Intermediates II. Photo-Activation of Hydrazones III. Organocatalyzed Cascade Conjugate Addition/Aldol Annulation of Organoboronates
This dissertation describes cascade transformations in constructing complex building blocks in synthetic organic chemistry. It includes the interceptions of carbene alkyne metathesis intermediates, boron enolate intermediates, fused cyclopropene intermediates, and boronic acid intermediates. First, …