Dissertations / Theses: 'Metal-mediated'

1

Howgego, David Christopher. "Metal-mediated molecular machines." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/7619.

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Nature abounds with ingenious nanoscopic machines employed to carry out all of the requisite tasks that collectively contribute to the molecular basis of life. This thesis focuses primarily on a sub-set known as "molecular walkers" which can perambulate along intracellular molecular motorways carrying out such essential tasks as vesicle transport and muscle contraction. A summary of these incredible natural motors is presented in Chapter I along with a review of the artificial small-molecule mimics reported to date. When elucidating a set of design principles for synthetic analogues, inspiration is taken from the mechanism of the biological bipedal motor protein kinesin with a focus on potential strategies to enable directional walking. Transition metal-ligand chemistry is utilised as one such strategy in Chapter II through the governance of walker-track interactions in the design, synthesis and operation of a bimetallic molecular biped. A palladium(II) moiety is selectively and intramolecularly stepped between pyridine-derivative binding sites in the track using a thermal stimulus in the presence of a coordinating solvent. Acid-base manipulations facilitate directional stepping by means of an energy ratchet mechanism allowing the track to do work on the biped unit and ultimately drive it away from equilibrium. The potential of malleable transition metal binding-event energetics is explored further in Chapter III with the design and synthesis of a platinum(II)-complexed [2]rotaxane. Thermodynamic and kinetic stimuli are investigated as means to mediate selective shuttling of a Pt-complexed macrocycle between two ligand binding sites in the thread. The substitution pattern of the ligands and the kinetic stability of the metal-ligand bonds afford exceptional metastability to the co-conformers of the molecule in the absence of an external stimulus providing the possibility for long-term information storage. In Chapter IV, a novel macrocycle is used to demonstrate the chemical orthogonality of acid-mediated hydrazone exchange with respect to the palladium(II) stepping mechanism described in Chapter II and show that two such motifs can be independently addressed within a single molecule. These linkages are then utilised as mutually exclusive chemo-selective switches to individually operate opposing feet in an unprecedented first-generation small-molecule walker-track system.

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2

Butters, Christopher. "Metal mediated organic transformations." Thesis, University of Bath, 1995. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260230.

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3

Trussell, Stephen John. "Transition metal-mediated organosilicon chemistry." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298136.

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4

Lindup, Richard J. "Metal-mediated borylation of fluorocarbons." Thesis, University of York, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434017.

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5

Baxter, John S. "Transition metal mediated annulation reactions." Thesis, University of Bristol, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324243.

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6

Warner, Benjamin Peter. "Mechanisms of metal-mediated cyclizations." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36008.

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7

Eriksson, Ludvig. "Transition Metal Mediated Transformations of Carboranes." Doctoral thesis, Uppsala University, Organic Chemistry, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3324.

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This thesis describes the use of copper and palladium to mediate transformations of carboranes, especially p-carborane.

1-(1-p-carboranyl)-N-methyl-N-(2-butyl)-3-isoquinolinecarboxamide, a carborane containing analogue of the peripheral benzodiazepine receptor (PBR) ligand PK11195, has been synthesised. A key step in the reaction is the copper (I) mediated coupling of p-carborane with ethyl 1-bromo-isoquinoline-3-carboxylate.

p-Carborane has been arylated on the 2-B-atom in high yields, using the Suzuki–Miyaura reaction. Thus the reaction between 2-I-p-carborane and various arylboronic acids [1-naphthyl-, phenyl-, 4-MeO-C₆H₄-, 3-CH₃CONH-C₆H₄-, 4-NC-C₆H₄-, 3-NO₂-C₆H₄-], gave the corresponding 2-aryl-p-carboranes in DME solution when reacted in the presence of cesium fluoride and the catalytic Pd₂(dba)₃–dppb system. Under the same conditions, the boron-boron bond forming reaction of two p-carboranylboronic esters (2-[(pinacolato)boron]-p-carborane and 2-[(neopentyl glycolato)boron]-p-carborane) was also shown feasible.

p-Carborane has been vinylated on the 2-B-atom in high yields by use of the Heck reaction. The coupling between 2-I-p-carborane and various styrenes [4-H-, 4-C₆H₄-, 4-Cl , 4-Br-, 4-NO₂-, 4-CH3O- and 4 CH₃ ] resulted in the formation of the correspondingtrans-β-(2-B-p-carboranyl) styrene in DMF solution when reacted in the presence of silver phosphate and the palladacycle Herrmann´s catalyst. The reaction was shown to proceed at higher rate with electron rich than with electron deficient olefins.

The feasibility of palladium-catalysed isotopic exchange of an iodinated closo-carborane with a radioisotope of iodine has been studied. 2-I-p-carborane was selected as a model compound. It was shown, that such isotopic exchange is possible and provides a high yield (83 ± 4.2 %) during 40 min long reaction. The reaction conditions were optimised, and it was demonstrated that presence of the tetra n-butylammonium hydrogensulphate is important in order to stabilise catalyst and provide reproducibility of labelling. In this work we have modified the methodology and extended the application to a wider range of iodinated carboranes. By the use of Herrmann’s catalyst in toluene at 100 °C this [¹²⁵I]-iodide labelling could be improved and extended. 2-I-p- 9-I-m-, 9-I-o-, 3-I-o-carborane, 1-phenyl-3-I-o-carborane and 1,2-diphenyl-3-I-o-carborane could be [¹²⁵I]-iodide labelled in high to excellent yields within 5 minutes.This reported palladium catalyzed radio-iodination of the uncharged closo-carboranes might find use in pharmacokinetic studies of carborane derivatives.

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8

McAlonan, Helena M. "Transition metal mediated approaches to pumiliotoxins." Thesis, Queen's University Belfast, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318792.

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9

Shaw, Graham Andrew. "Solvent mediated synthesis of metal chalcogenides." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326065.

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10

Hunter, Rupert Alexander. "Transition metal mediated synthesis of heterocycles." Thesis, University of Southampton, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402426.

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11

Stenton, Benjamin James. "Metal mediated mechanisms of drug release." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/284402.

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In this thesis will be described research towards the development of bioorthogonal bond-cleavage reactions, and their applications in targeted drug delivery (Figure 1). The first project relates to the development of a palladium mediated bond-cleavage or "decaging" reaction which can cause a propargyl carbamate to decompose and release an amine. This was further developed by the incorporation of a protein modification handle which allowed an amine-bearing drug to be covalently ligated to a protein by a palladium-cleavable linker. This chemistry was demonstrated by the conjugation of the anticancer drug doxorubicin to a tumour targeted anti-HER2 nanobody. The drug could then be delivered to cancer cells upon addition of a palladium complex. The second project relates to the development of a platinum mediated bond-cleavage reaction. This was developed with the aim of using platinum-containing anticancer drugs - such as cisplatin - as a catalyst to cause drug release reactions in tumours. In this reaction an alkyne-containing amide can decompose to release an amine upon addition of platinum complexes, and was applied to the release of prodrugs of the cytotoxins monomethylauristatin E and 5-fluorouracil in cancer cells. A cisplatin-cleavable antibody-drug conjugate was designed and synthesised, and progress towards its biological evaluation will be discussed.

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12

IENGO, ELISABETTA. "METAL-MEDIATED SUPRAMOLECULAR ASSEMBLIES OF PORPHYRINS." Doctoral thesis, Università degli studi di Trieste, 2002. http://thesis2.sba.units.it/store/handle/item/12433.

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13

Guillo, Nathalie Christine Monique Marie. "Aspects of transition metal-mediated organic synthesis." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267885.

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14

Keen, Stephen Philip. "Metal-mediated manipulation of #alpha#-amino acids." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299177.

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15

Marco, Maria. "Methodology development for traditionally metal-mediated transformations." Thesis, King's College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407594.

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16

Ramsay, Donna Louise. "Alkali-metal-mediated cleave and capture chemistry." Thesis, University of Strathclyde, 2015. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25765.

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Whilst metallation, a fundamental reaction in synthetic chemistry, is well established with mono-metallic organolithium reagents, recently a second generation of bimetallic reagents has been gathering momentum, evading some of the limitations associated with organolithium reagents. This study extends the current research in this area of synergic bimetallic chemistry and reports the synthesis and characterisation of new compounds from reactions of bases with different substrates, as well as detailed studies of the starting reagents. A new method for synthesising the utility organoamidolithium reagent LiTMP by way of a transmetallation reaction between tBuLi and Zn(TMP)₂ is described. This realised a new crystalline polymorph of LiTMP in the cyclotrimer (LiTMP)₃ 2.1. Remarkably an interrogation of the two most popular aluminating reagents “LiTMP·Al(iBu)₃” 3.1 and “LiTMP·Al(TMP)(iBu)₂” 3.2 established that 3.1 is not a single species as previously reported but in fact a complex mixture of five distinct species all in equilibria with each other. Additionally it was discovered that the modus operandi of both reagents is a two-step lithiation - trans-metaltrapping protocol, and not by direct alumination. The pharmacologically relevant amine DMPEA was studied with a range of bimetallic base mixtures. Post metallation and subsequent β-elimination the NMe₂ fragment was captured in three different crystalline compounds: [TMEDA·Na(TMP)(NMe₂)Zn(tBu)] 4.2, [PMDETA·Li(NMe₂)Zn(tBu)₂] 4.3 and [THF·Li(TMP)(NMe₂)Al(iBu)₂] 4.4. The first crystal structure where DMPEA is bonded to a metal has also been revealed in [DMPEA·Li(TMP)Zn(Me)₂] 4.5. Probing ferrocene with bimetallic mixtures afforded a range of mono- and dideprotonated products depending on the stoichiometry used. Both zincations in TMEDA·Na(μ-TMP)[μ-(C₅H₄)Fe(C₅H₅)]Zn(tBu) 5.1 and [TMEDA·Na(μ-TMP)Zn(tBu)]₂(C₅H₄)₂Fe 5.2 and aluminations in THF·Li(μ-TMP)[μ- (C5H4)Fe(C5H5)]Al(iBu)2 5.4, [THF·Li(μ-TMP)Al(iBu)2]2(C5H4)2Fe 5.5, [TMP(H)·Li(μ-TMP)Al(iBu)2]2(C5H4)2Fe 5.6 and TMP(H)·Li(TMP)[(C5H4)Fe(C5H5)]Al(iBu)2 5.7 were possible. The zinc system also provided the novel ferrocenophane type structure [{Fe(C₅H₄)₂}₂{Na₂Zn₂(tBu)₂·(THF)₆}] 5.8, as well as hints of a possible polymetallated product.

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17

Huang, Xin. "Theoretical studies on transition metal mediated reactions /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202004%20HUANG.

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18

Filippov, Igor 1971. "Metal-mediated hydrodenitrogenation catalysis: Designing new models." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282749.

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Reduction of Ta(DIPP)₂Cl·OEt₂(DIPP= 2,6-OC₆H₃ⁱPr₂) with 2 equiv. of NaHg in the presence of 3,5-lutidine results in cyclometalation of DIPP to give TaCl(DIPP)-(OC₆H₃ⁱPr-η²(C,C)-CMe =CH₂)(3,5-lutidine)₂ (10) in moderate yield. Metallacycle 10 was also isolated from the reaction of (η⁶-C₆Me₆)Ta(DIPP)₂Cl with 3,5-lutidine. Examination of both crude reaction mixtures by ¹H NMR revealed 10 to be the major product without any indication of the formation of η²-lutidine species. These observations suggest that η²(N,C)-coordination of 3,5-lutidine is kinetically incompetitive with respect to the cyclometalation of DIPP by d² tantalum. Such undesired reactivity of DIPP can be potentially inhibited by the use of linked aryloxide ligands to prevent close approach of metalatable C-H bonds of DIPP to the metal center. An efficient route to a family of silane-linked aryloxides was developed. Tris(2-hydroxy-3-isopropylphenyl)methylsilane (H₃TIPSI, 59), bis(2-hydroxy-3-isopropyl-phenyl)diphenylsilane (H₂BIPSI, 61), and bis(2-hydroxy-3-isopropylphenyl)dimethyl-silane (H₂BIPSI, 60) were obtained via deprotection of the parent silane-linked anisoles. The anisoles were prepared in high yields by treating 2-methoxy-3-isopropyl-phenyllithium·0.5TMEDA (27·0.5TMEDA) with an appropriate amount of chloroalkylsilanes. The deprotection was carried out employing BBr₃ in CH₂Cl₂ followed by hydrolysis of the intermediate boron ethers in the presence of a non-nucleophilic base to avoid protiodesilylation. Additionally, a significantly improved synthesis of 1,2-bis(3-isopropyl-2-hydroxyphenyl)ethane (H₂BIPP, 40) employing 27·0.5TMEDA as a starting reagent is reported. 2-Methoxyphenyllithium 27·0.5TMEDA was prepared via catalytic ortho-directed metalation of 2-isopropylanisole, and the mechanistic aspects of such metalations are presented. Trinuclear complex (AlBr₂)₃TIPSI (55) was isolated from the reaction of Me₃TISPI with 3 equiv. of AlBr₃ in benzene at 60°C. Preliminary reactivity studies show that Me₃TIPSI (49) and Me₂BIPSI (51) can be reacted with TaBr₅ under similar conditions to give Br₃Ta(MeTIPSI)(THF)₂ (62) and Br₃Ta(BIPP)OEt₂ (63), respectively, after appropriate reaction work ups.

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19

Pawar, Lokesh. "Metal mediated intramolecular transformations of pyridine substrates." Diss., University of Iowa, 2013. https://ir.uiowa.edu/etd/5040.

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Nature continuously provides fascinating and complicated structures which offer synthetic chemists amazing opportunities for the design of new methods for the natural product synthesis. Nitrogen containing aza-heterocycles are of unparalleled importance in natural product, bioorganic and medicinal chemistry. Pyridine in particular is one of the most common aza-heterocycles encountered in natural products, medicinal and materials chemistry. Pyridine derivatives also server as precursors to functionalized piperidines, which are likewise common structural motifs in bioactive and functionalized materials. Thus developing synthetic methods suitable for the manipulation of pyridine ring systems remains an important objective in the organic chemistry community. We approached this objective by two different routes. In the first method, we used the nucleophilicity of the benzylic position of the 4-alkyl pyridine substrates to engage in gold (I) catalyzed 5 or 6-endo dig cyclizations with attached alkynyl amide groups. Processing of the so formed cycloadducts under hydrolytic conditions then afforded substituted pyridines with functionalized lactams. In the second approach, we investigated the feasibility of Pd-catalyzed cyclization of 3-substituted pyridines. It was envisioned that Pd(0) catalysts could react with alkyne substituents positioned along the pyridine periphery such that nucleophilic alkeynyl moiety would be generated. Activation of the pyridine by N-alkylation or acylation would then result in intramolecular cyclization. Rather than the desired reaction pathway, however, only products of alkyne hydroarylation were observed.

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20

Minatoya, Machiko Buszek Keith R. "New electrophilic partners for metal-mediated coupling reactions." Diss., UMK access, 2007.

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Thesis (M.S.)--Dept. of Chemistry. University of Missouri--Kansas City, 2007.
"A thesis in chemistry." Typescript. Advisor: Keith R. Buszek. Vita. Title from "catalog record" of the print edition Description based on contents viewed Dec. 18, 2007 Includes bibliographical references (leaves 46-51). Online version of the print edition.

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21

Young, Mary Jane. "Phosphate diester cleavage mediated by transition metal complexes." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40473.

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Two independent studies have been developed in this thesis. In the first study, the reactivities of metal-alkoxide and metal-hydroxide nucleophiles are compared for cleaving phosphate diesters. In the second study, the reactivity of a dinuclear metal complex is compared to a mononuclear metal complex for hydrolyzing RNA.
Copper(II) complexes of bis(2-pyridylmethyl)amine (Cu(II)bpa), N-(2-hydroxyethyl)bis(2-pyridylmethyl)amine (Cu(II)hebpa) and N-(3-hydroxypropyl)bis(2-pyridylmethyl)amine (Cu(II)hpbpa) have been synthesized and their reactivities and mechanisms for cleaving bis(2,4-dinitrophenyl) phosphate (BDNPP) have been investigated. Cu(II)hpbpa is observed to be the most reactive (k = 7.2 $ times$ 10$ sp{-1}$ M$ sp{-1}$ s$ sp{-1}$ at 25$ sp circ$C, pH 8.8) for cleaving BDNPP followed by Cu(II)bpa (k = 2.0 $ times$ 10$ sp{-2}$ M$ sp{-1}$ s$ sp{-1}$) and Cu(II)hebpa (k = 2.0 $ times$ 10$ sp{-2}$ s$ sp{-1}$). HPLC product analyses indicated that Cu(II)hpbpa cleaves BDNPP mostly through transesterification while the complexes Cu(II)bpa and Cu(II)hebpa cleave BDNPP predominantly by hydrolysis. The differences in the mechanisms and the reactivities are explained in terms of the differences in the structures of the three copper(II) complexes.
Copper(II) complexes of 1,8-bis(1,4,7-triazacyclononyl-N-methyl)naphthalene (tntn), 1,4,7-triazacyclononane (tacn), and N-benzyl-1,4,7-triazacyclononane (btacn) have been prepared and their reactivities compared for cleaving RNA. The novel dinuclear copper(II) complex, Cu(II)$ sb2$tntn, is observed to be 200-500 fold faster per metal center than the mononuclear copper(II)complexes, Cu(II)tacn and Cu(II)btacn, for cleaving a diribonucleotide, ApA, and its cyclic phosphate intermediate, $2 sp prime3 sp prime$-cAMP. Cu(II)$ sb2$tntn (2.0 mM) reduces the half life of ApA (0.05 mM) to 50 minutes (pH 6, 50$ sp circ$C); this represents a rate acceleration of approximately 10$ sp5$ fold over the background hydroxide rate. The half life of $2 sp prime3 sp prime$-cAMP (0.05 mM) is decreased to 4 minutes in the presence of Cu(II)$ sb2$tntn (2.0 mM, pH 6, 25$ sp circ$C); this represents a rate acceleration of about 10$ sp8$ fold over the background hydroxide rate.

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22

Lawson, Iain M. "Transition metal mediated synthesis of biologically important heterocycles." Thesis, University of Newcastle Upon Tyne, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427320.

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23

Russell, Claire. "New metal-mediated regio- and stereoselective organic processes." Thesis, University of Strathclyde, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436102.

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Hogg, Lorna. "Alkali-metal-mediated metallations with emphasis on zincations." Thesis, University of Strathclyde, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501820.

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25

Pfrunder, Michael Craig. "Halogen bond mediated crystal engineering of metal complexes." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/71083/1/Michael_Pfrunder_Thesis.pdf.

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This project explored the potential for halogen bonds to predictably organise metal-containing molecular building blocks in crystalline materials. A novel method for the halogen bond mediated crystal engineering of metal complexes was discovered, which led to the preparation of new materials with potential applications in molecular switching devices and advanced memory storage systems.

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26

Fergani, Hadi. "Metal-atom-mediated chemical transformations, the reaction of group 13 metal atoms with arenes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0017/MQ46480.pdf.

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27

Agarwal, Sameer. "Transition Metal-Mediated Syntheses of Yohimbane and Indolizidine Alkaloids." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1119360417222-39155.

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Polycyclic nitrogen containing heterocycles form the basic skeleton of numerous alkaloids and physiologically active drugs. Alloyohimbane was obtained from 3,4-dihydro-â-carboline using an iron-mediated [2+2+1] cycloaddition as the key-step. The bis-TMS-diyne was conveniently obtained by the C-alkylation of 3,4-dihydro-â-carboline followed by N-alkylation. Demetalation of the iron-complex followed by hydrogenation, E-ring expansion, and reduction provided alloyohimbane, a structurally and biologically interesting substance, via a linear eight-step sequence in 7% overall yield based on 3,4-dihydro-â-carboline. Another sequence provided (±)-alloyohimbane and (±)-3-epi-alloyohimbane in nine steps. The pyrrole unit occurs in a variety of naturally occurring compounds, pharmaceutical products and polymers. A novel two-step procedure for the synthesis of pyrroles by addition of a propargyl Grignard reagent to a Schiff base and subsequent silver(I)-promoted oxidative cyclization of the resulting homopropargylamine has been developed. The generality of this reaction was proven by the synthesis of a broad variety of substituted pyrroles using silver(I)-promoted cyclization. A three-step synthesis of (±)-harmicine, a natural product isolated from the Malaysian plant Kopsia griffithii having strong anti-leishmania activity, from 3,4-dihydro-â-carboline is achieved by addition of 3-trimethylsilylpropargyl Grignard reagent, Ag(I)-promoted oxidative cyclization to a pyrrole, and chemoselective hydrogenation of pyrrole ring. Total synthesis of anti-tumor active crispine A and biologically active 1,2,3,5,6,10b-hexahydropyrrolo[2,1-a]isoquinoline have been achieved in three steps using silver(I)-promoted oxidative cyclization as key step.

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Swift, Michael D. "Investigation of metal mediated reactions for natural product synthesis." Thesis, University of Glasgow, 2009. http://theses.gla.ac.uk/621/.

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During the course of the studies outlined in this thesis, an ether-directed Pd(II)-catalysed aza-Claisen rearrangement reaction that had previously been developed by the Sutherland group was expanded to include more functionalised rearrangement substrates. This methodology has been applied for the synthesis of several natural products including dihydroxylated-amino acids. Further investigation of substrates for the rearrangement led to the synthesis of other substituted trichloroacetimidates. Rearrangement of these compounds demonstrated the role of steric strain on the stereocontrol of the rearrangement and also highlighted the role that solvent can have upon the diastereoselectivity of ether-directed rearrangements. In addition to this, a novel tandem aza-Claisen rearrangement and ring closing metathesis reaction has been developed. This reaction allows the synthesis of cyclic allylic trichloroacetamides in excellent yields from simple allylic alcohols. The use of commercially available chiral rearrangement catalysts allowed a highly enantioselective tandem process to be developed. Further development of this process has provided an ether-directed tandem aza-Claisen rearrangement and RCM reaction which occurs with high yield and diastereoselectivity to provide functionalised cyclic products. The use of these compounds for the total synthesis of the amaryllidaceae alkaloid (+)-gamma-lycorane was also investigated.

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Brown, John Alexander. "Emerging novel systems for selective metal-mediated organic synthesis." Thesis, University of Strathclyde, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435122.

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30

Jiang, Quan. "Computational Studies of Catalysis Mediated by Transition Metal Complexes." Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1505187/.

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Computational methods were employed to investigate catalytic processes. First, DFT calculations predicted the important geometry metrics of a copper–nitrene complex. MCSCF calculations supported the open-shell singlet state as the ground state of a monomeric copper nitrene, which was consistent with the diamagnetic character deduced from experimental observations. The calculations predicted an elusive terminal copper nitrene intermediate. Second, DFT methods were carried out to investigate the mechanism of C–F bond activation by a low-coordinate cobalt(I) complex. The computational models suggested that oxidative addition, which is very rare for 3d metals, was preferred. A π–adduct of PhF was predicted to be a plausible intermediate via calculations. Third, DFT calculations were performed to study ancillary ligand effects on C(sp3)–N bond forming reductive elimination from alkylpalladium(II) amido complexes with different phosphine supporting ligands. The dimerization study of alkylpalladium(II) amido complexes indicated an unique arrangement of dative and covalent Pd-N bonds within the core four-membered ring of bimetallic complexes. In conclusion, computational methods enrich the arsenal of methods available to study catalytic processes in conjunction with experiments.

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31

Liang, Shengwen. "Nitrene Transfer Reactions Mediated by Transition Metal Scorpionate Complexes." Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1339005115.

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32

Arbour, Jannine Louise. "Metal-mediated intramolecular hydroamination and hydro(acy)alkoxylation reactions." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9203.

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This PhD thesis describes work undertaken to effect asymmetric catalysis in hydroamination and hydro(acy)alkoxylation reactions of allenes. The introductory Chapter provides an overview of recent advances in asymmetric heterofunctionalisation reactions of allenes. This includes intra- and inter-molecular reactions involving C-N and C-O bond formations. Chapter 2 begins by comparing the preparation of a γ-allenic alcohol by two different synthetic routes and its subsequent use in intramolecular hydroalkoxylation reactions using copper(II) and silver(I) salts. From this study, the ability of silver diphosphine complexes to facilitate enantioselective hydroalkoxylation reactions in a 5-exo-trig fashion was discovered. Extensive reaction optimisation was undertaken, however only moderate ee’s and conversions were observed. In Chapter 3, the use of other metal Lewis acids to catalyse hydroalkoxylation reactions of γ-allenic alcohols is presented. DFT calculations undertaken by a colleague (Prof H. S. Rzepa) were used to rationalise the observed regioselectivities with silver(I), zinc(II), and tin(II) triflates. From DFT calculations, the metal counteranion was found to be intimately involved in the C-O bond formation. In the following two Chapters, the possibility of asymmetric synthesis by using chiral anionic ligands is discussed. In Chapter 4, additional γ-allenic alcohols and β-allenic acids were synthesised for intramolecular hydroalkoxylation or hydroacyalkoxylation reactions respectively. In Chapter 5, the respective γ-allenic amines were prepared for intramolecular hydroamination. In both cases, the outcome, scope and limitations of the reaction are discussed. In Chapter 6, an overall conclusion and future work is discussed. The last Chapter contains experimental procedures and characterisation data of all the compounds synthesised during the course of this project.

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33

Sparkes, Robert P. "Carbocations in palladium crystals." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249213.

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Wang, Long [Verfasser]. "The transition metal-mediated N-functionalizations of sulfoximines / Long Wang." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2014. http://d-nb.info/105216062X/34.

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Dabb, Serin Lloyd Chemistry Faculty of Science UNSW. "Hydrazine in late transition metal-mediated N-C bond formation." Publisher:University of New South Wales. Chemistry, 2008. http://handle.unsw.edu.au/1959.4/41428.

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This thesis describes investigations into the metal-mediated formation of nitrogen-carbon bonds from hydrazines and alkynes. Rh, Ir, Ru and Os metal complexes containing bidentate P,N- and N,N-donor ligands were all studied during the course of this work. A series of stereoisomers of metal complexes of general formula MCl2(PyP)2 (where M = Ru and Os, PyP = 1-(2-(diphenylphosphino)ethyl)pyrazole) (2.01-2.05) were synthesised. The isomerisation process of complexes 2.01-2.05 in solution was investigated. The ruthenium complex RuCl2(CO)(1-P-PyP)(2-P,N-PyP) (2.14), which contains one pendant PyP ligand bound through the P-donor ligand was synthesised, confirming the potential hemilability of the mixed P,N-donor ligand PyP. Chloride abstraction from the ruthenium complex trans,cis,cis-RuCl2(PyP)2 (2.01) was achieved using either a sodium or silver salt to yield the dimeric complexes of general formula [Ru(μ-Cl)(PyP)2]2[X]2 (where M = Ru, X = OSO2CF3 (2.06), BF4 (2.07), BPh4 (2.08), and BArF 2.09). [Os(μ-Cl)(PyP)2]2[BPh4]2 (2.10) was synthesised from sodium tetraphenylborate and trans,cis,cis-OsCl2(PyP)2 (2.04). The reactivity of dimeric complexes 2.06 and 2.08 towards substituted hydrazines was investigated. The methylhydrazine complex [Ru(PyP)2(NH2NHMe)][Cl][BPh4] (3.12) was synthesised. The methylhydrazine adduct of 3.12 binds to the metal centre in an end-on fashion via the NH2 group in solution, and in a bidentate fashion in the solid-state. This is the first reported example of a ruthenium complex containing a bidentate hydrazine ligand. The ruthenium-vinylidene complexes [RuCl(Me2PyP)2(=C=C(H)Ph)]BPh4 (4.15) and [RuCl(Me2PyP)2(=C=C(H)n-Bu)]BPh4 (4.16) (Me2PyP = 1-(2-(diphenylphosphino)ethyl)-3,5-dimethylpyrazole) were synthesised from trans,cis,cis-RuCl2(Me2PyP)2 (4.10) and the appropriate terminal alkyne. The reaction of alkynes with ruthenium complexes containing the PyP ligand was also investigated. Nitrogen-carbon bond formation was achieved through reaction of mono-substituted hydrazines with 4.06 and 4.07 to yield complexes of general formula [RuCl(1-P-Me2PyP)(2-P,N-Me2PyP)(2-N,C-(NH2N(R2)C(CH2R1)]BPh4 (where R1 = R2 = Ph (4.19), R1= Ph, R2 = Me (4.20), R1 = n-Bu, R2 = Ph, (4.21) or R1 = n-Bu, R2 = Me (4.22)). The mechanism of the formation of the stable metallocyclic complexes 4.19-4.22 was elucidated through studies of the reactivity of 4.15 towards a series of amines and hydrazines and relies on the labile nature of the N-donor of the P,N-donor ligand Me2PyP. A method for the synthesis of triflate complexes of rhodium Rh(PyP)(CO)(OSO2CF3) (5.13) and Rh(PyPhP)(CO)(OSO2CF3) (PyPhP = 1-(2-(diphenylphosphino)phenyl)pyrazole) (5.14) from rhodium chloride complexes was developed. The solid-state structure of rhodium triflate complex 5.14, which contained the more sterically rigid ligand PyPhP, exhibited a much greater distortion from the ideal square planar geometry than the rhodium analogue 5.13 which contains the PyP ligand. The triflate group of 5.13 and 5.14 was displaced by substituted hydrazines to yield new hydrazine complexes of rhodium. A series of Rh and Ir complexes with bidentate P,N- and N,N-donor ligands were found to catalyse the intermolecular hydroamination of alkynes with hydrazines. [Ir(bpm)(CO)2]BArF (6.08) was found to be the most efficient catalyst of those studies for this transformation, and was amongst the most efficient catalysts reported to date for this transformation. The influence of counter-ion was highly significant in the catalysed intermolecular hydroamination reaction. The substrate scope of the intermolecular hydroamination of alkynes with hydrazines was investigated using [Ir(bpm)(CO)2]BArF (6.08) as the catalyst.

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Illesinghe, Jayamini P. M. "Synthesis and use of nitrogen heterocycles in metal mediated reactions." Monash University, School of Chemistry, 2004. http://arrow.monash.edu.au/hdl/1959.1/9637.

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Pawlikowski, Andrew V. "Developments in late metal-mediated C-N bond forming reactions /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/8489.

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Zhang, Xin-Hao. "Theoretical studies on the mechanistic aspects of metal mediated reactions /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202007%20ZHANG.

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Salacinski, Henryk Julian. "Studies of biologically relevant metal mediated routes for radical generation." Thesis, Queen Mary, University of London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299697.

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Chabrol, Virginie. "Functionalized latex particles as substrates for metal mediated radical polymerization." Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-01012004.

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Le sujet de cette thèse consiste à incorporer une couronne de polymère hydrophile à la surface de particules de latex par amorçage et croissance en utilisant la polymérisation radicalaire contrôlée par transfert d'atome induite par les métaux. Les particules de latex, obtenues par, polymérisation radicalaire en émulsion ont été fonctionnalisées avec un " inimère ", monomère comportant une fonction halogénée capable de jouer le rôle d'amorceur dans l'étape de greffage. Cette étape de greffage a ensuite été effectuée en présence de CuBr2, PMDETA et d'un métal à valence zéro tel que le cuivre, àtempérature ambiante à partir de latex non post-purifiés (présence de tensio-actif et d'amorceur résiduels et à taux de solide élevés). Au cours du processus, l(incorporation de l'inimère et de la couronne hydrophile a été vérifée par ToF-SIMS (time-of-light secondary ion mass spectrometry), par FTIR et par l'étude des propriétés colloïdales des latex greffés.

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Pearson, Colin Matthew. "Strategic application of transition metal-mediated methods in organic synthesis." Thesis, University of Strathclyde, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435134.

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Blair, Victoria L. "Advances in alkali-metal-mediated manganation and comparisons with magnesiation." Thesis, University of Strathclyde, 2010. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=12391.

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Campbell, Ross. "Alkali metal mediated bimetallic main group and transition organometallic chemistry." Thesis, University of Strathclyde, 2012. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=16944.

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Bhushan, Bhaskar. "Unnatural amino acids as metal-mediated probes of biological function." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:4b1cbed6-1151-4b9f-ad97-aa5765cc9384.

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Conjugation reactions on proteins have been used to access various post-translational modifications, for targeted delivery of drugs, for microscopy, and in studying receptor-ligand interactions. However, the ability to modify native proteins is constrained by the reactive functionalities of naturally occurring amino acids. This has driven research into the incorporation of unnatural amino acids (UAAs) into proteins. Research in this area has been motivated both by the possibility of increasing the breadth of chemical techniques for protein modification by introducing novel 'bio-orthogonal' reactive groups via UAA incorporation, as well as generating well-defined conjugates by the site-selective incorporation of these UAAs into proteins. The objective of this thesis is to both expand the diversity of UAAs for access to new metal-mediated reactions on proteins, as well as to utilise these reactions to reveal functional information about a range of biological systems. A brief introduction into current protein conjugation and UAA incorporation methods will be made in Chapter 1. In Chapter 2, the genetic incorporation of alkene-bearing UAAs into recombinant proteins expressed in both bacterial and mammalian systems is discussed. This technique is demonstrated to enable Ru-catalysed olefin cross-metathesis (CM) reactions on the resultant proteins. This work builds upon previously established methods to chemically incorporate CM handles onto proteins. The rational design of UAAs, as well as assays and modelling studies to screen them for recognition by the cellular incorporation machinery are discussed in detail. The expression of a range of alkene-tagged recombinant proteins, their complete characterisation, as well as the development of a more general protocol for on-protein CM is elucidated. In Chapter 3, the utility of UAA incorporation to probe mammalian cell translation systems is examined. Incorporation of an azide-bearing UAA, in addition to heavy stable-isotope labelled amino acids is used to uncover a previously unreported system of protein synthesis in mammalian cell nuclei, along with rapid metabolic degradation of the synthesised peptides. Various orthogonal methods for the detection of this system as well as possible reasons for its conservation are discussed. In Chapter 4, UAA incorporation and metal-mediated bioconjugation reactions are utilised in the development of a novel and generally applicable proteomics technique. This technique is used to determine quantitative changes in cell proteomes in response to external stimuli, and may be applied to systems to which traditional proteomics techniques cannot, such as ex vivo primary cells. Finally, in Chapter 5, further applications of UAA incorporation are discussed. Preliminary results are reported in efforts to use UAAs in the vibrational Raman microscopic imaging of biological systems, in generating HIV vaccines, and inducing T-cell stimulation.

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Pereira, Fernanda Antonia. "Controlled folding and conformational switching in metal-mediated DNA constructs." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2016. http://hdl.handle.net/11858/00-1735-0000-0023-3DB9-8.

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Zhang, Yu. "Visible Light-Mediated Metal-Free Photocatalytic Oxidative Reactions and Cycloadditions." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-14EF-8.

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Strozier, Joseph Lee Jr. "Halogen Mediated De-Interpenetration of Interpenetrated Zn Metal Organic Frameworks." Youngstown State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1587657198606781.

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Ando, Tsuyoshi. "DESIGN AND MECHANISM OF TRANSITION METAL-MEDIATED LIVING RADICAL POLYMERIZATION." Kyoto University, 2000. http://hdl.handle.net/2433/180981.

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Ward, William, and William Ward. "Metal Ion-Mediated Folding and Catalysis of the Hammerhead Ribozyme." Thesis, University of Oregon, 2012. http://hdl.handle.net/1794/12375.

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The factors that determine RNA structure formation, stability, and dynamics are inexorably linked to RNA function. The Hammerhead ribozyme (HHRz) has long served as a model for studying metal-dependent folding and catalysis in RNA. The HHRz consists of three helices meeting at a common junction of conserved nucleotides that form the active site of the ribozyme. Current models of metal-dependent HHRz function involve a requirement for divalent metals to globally fold the ribozyme at low metal concentrations, followed by a second metal-dependent process which activates the HHRz for catalysis. The exact role of metal ions in activating HHRz catalysis is still a subject of investigation. We used 2-aminopurine substitutions near the active site of the ribozyme to determine if this second metal-dependent process involves a conformational rearrangement in the core of the ribozyme. We find evidence for a conformational change beyond global folding in the core of the ribozyme that not only correlates with metal activated catalysis but is also sensitive to the identity of the metal ions used for folding. Though phosphorothioate substitutions indicate that a ground-state coordination of a catalytic metal to the scissile phosphate is required for efficient catalysis, our folding studies show that this coordination event is not absolutely required for folding of the HHRz core. To investigate possible roles for metal ions in general acid-base catalysis, we tested the pH dependence of the HHRz rate using a variety of metal ions. We find the pH dependent rate profile of the ribozyme is shifted by transition metal ions, whereas other group II metals show similar profiles to Mg

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Gillespie, Derek A. "Novel N-Heterocyclic carbenes as ligands for metal-mediated asymmetric processes." Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492558.

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N-heterocyclic carbenes (NHCs) have emerged over the last two decades as an important class of ligands in transition metal complexes, main group chemistry and organocatalysis. NHCs are now common replacements for phosphines in transition metal chemistry.

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