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Dissertations / Theses on the topic 'Nucleophilic'

Author: Grafiati

Published: 4 June 2021

Last updated: 6 September 2023

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1

Antonsson, Rositha. "Nucleophilic aromatic substitutions using ethyl 3-mercaptopropionate as nucleophile : Scope and limitations." Thesis, Södertörn University College, School of Life Sciences, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-1517.

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The scope and limitations of nucleophilic substitutions of aryl halides have been studied using ethyl 3-mercaptopropionate as nucleophile and microwave heating. A diversity of aromatic compounds have been investigated according to different types of leaving groups, regio isomers and substituents. Experimental design has been used as a tool to optimize the reaction. An electron-withdrawing group in ortho or para position of the leaving group proved to be necessary for a positive outcome of the reaction. Fluorine was, without competition, the best leaving group. Some examples of how the synthesized aryl sulfanyl propionates can be used as starting material for producing aryl thio ethers, sulfoxides and unique benzothiophenes are described.

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2

Thompson, Claire. "Aromatic nucleophilic nitration." Thesis, University of Exeter, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390199.

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3

Harris, David T. "New Nucleophilic Organocatalysts." Thesis, The University of Arizona, 2011. http://hdl.handle.net/10150/144597.

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Acyl-transfer reactions have become commonplace in organic synthesis and organocatalysis of these reactions is becoming increasingly popular. 4-Dimethylaminopyridine has proven to be very useful in acylations; over the recent years chiral and more reactive analogs have received much attention. Interestingly, catalysis of acyl-transfers by diamines has also been shown to be effective. We present the synthesis of several DMAP analogs containing heteroatoms near the nucleophilic nitrogen. These analogs of DMAP vary from basic amidines, oxazolines, and amines, to alcohols, and fluoro-derivatives all of which may provide hydrogen bonding to the alcohol undergoing acyl-transfer. Since Steglich proposed the need for a base in the DMAP catalyzed acyl-transfer transition state no studies have been performed on the effect that nearby hydrogen bonding or nearby bases might have on catalytic efficiency and enantioselectivity of acylations. The variety of compounds synthesized should allow for studies into rate and selectivity enhancements in nucleophilic pyridine catalysis.

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4

Lees, Inez Nancy Lloyd. "Nucleophilic polymers for scavenging." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613095.

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5

Wei, Yin. "Theoretical Studies in Nucleophilic Organocatalysis." Diss., lmu, 2009. http://nbn-resolving.de/urn:nbn:de:bvb:19-95248.

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6

Maryasin, Boris. "Theoretical investigations in nucleophilic organocatalysis." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-138820.

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7

Cresswell, Alex. "New methods for nucleophilic fluorination." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:612ea592-2f52-407b-b761-36b02b746e9d.

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This thesis describes investigations into the utility of boron fluorides and tetrafluoroborates as sources of nucleophilic fluorine. Chapter 1 discusses the history and importance of the field of organofluorine chemistry and outlines some of the principle motivations for the site-selective fluorination of organic molecules. Some of the most commonly useed methods of nucleophilic fluorination are briefly surveyed, with an emphasis on the formation of fluorinated stereogenic centres. Literature precedent for the use of tetrafluoroborates and boron trifluoride as nucleophilic fluorinating agents is also presented. Chapter 2 describes the development of a highly regio- and stereoselective S_Ni-type ring-opening fluorination of trans-β-substituted aryl epoxides using BF₃●OEt₂ as a nucleophilic fluorinating agent. This robust and scalable protocol grants efficient access to a variety of functionalised benzylic fluoride building blocks, and provides a solution to the problem of stereocontrol in the synthesis of this class of compounds. To highlight the utility of the resultant syn-fluorohydrins in the synthesis of stereodefined β-fluoro β-aryl amines, their elaboration to a range of aryl-substituted β-fluoroamphetamines is demonstrated. Chapter 3 introduces the concept of tuning the reactivity of BF₃ by replacing one or two of the fluoro ligands on boron for electron-donating alkoxy group(s). On this basis, pinacolatoboron fluoride (pinBF) [which may be prepared in situ by pre-mixing BF₃●OEt₂ and bis(O-trimethylsilyl)pinacol] is identified as a superior reagent to BF₃●OEt₂ for the ring-opening fluorination of trans-β-substituted aryl epoxides bearing electron-rich aryl groups. Chapter 4 details a highly regioselective and stereospecific S_N2-type ring-opening fluorination of 2,3- and 3,4-epoxy amines using HBF₄●OEt₂ as a nucleophilic flurine source. The reactions are both operationally simple to perform and readily scalable, and proceed to completion within 5 min at ambient temperature, providing a highly practical and economical route to stereodefined amino fluorohydrins. To highlight the synthetic utility of this reaction in the preparation of pharmaceutically-important β-fluoro amines, a concise de novo asymmetric synthesis of (S,S)-3-deoxy-3-fluorosafingol is performed. Chapter 5 chronicles the successful development of a protocol for the direct hydroxyfluorination of allylic amines to the corresponding amino fluorohydrins, using m--CPBA as the oxidant and HBF₄●OEt₂ in a dual role as both the Brønstead acid N-protecting agent and nucleophilic fluorine source. With chiral allylic amines which are conformationally biased or constrained, the diastereofacial selectivity of the reaction can be controlled by altering the concentration of HBF₄●OEt₂ employed in the reaction, allowing for a diastereodivergent hydroxyfluorination process. The synthetic utility of this methodology is demonstrated via its application to the diastereodivergent synthesis of 4-deoxy-4-fluoro-L-xylo-phytosphingosine and 4-deoxy-4-fluoro-L-lyxo-phytosphingosine, each in 5 steps from Garner's aldehyde. Chapter 6 contains full experimental procedures and characterisation data for all compounds synthesised in chapters 2, 3, 4 and 5.

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8

Murray, Christopher B. "New methodology for nucleophilic fluorination." Thesis, Durham University, 2003. http://etheses.dur.ac.uk/3687/.

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This work describes the development of three methods for the fluorination of electrophilic substrates:1.) The reaction of caesium fluoride with perfluoro(2-methylpent-2-ene) leads to the formation of perfluoro(2-methylpentan-2-yl)caesium. This perfluoroalkyl carbanion has been shown to undergo significant fluoride ion exchange at temperatures above 60 C. Thus, reaction of a solution of the carbanion with a suitable electrophile resulted in the selective formation of a carbon-fluorine bond or perfluoroalkylation of the electrophile.2.) Caesium fluoride has been developed as a moderately effective nucleophilicfluorinating agent in the Room Temperature Ionic Liquid (RTIL) solvent [BMIM][PF(_6)]. The fluorination of a range of volatile substrates was studied, and fluorination in the absence of a conventional organic solvent was demonstrated. Recycling of the solvent has been investigated, as has the decomposition of [BMLM] [PF(_6)] in the presence of caesium or potassium fluoride at elevated temperatures.3.) Reaction of a highly fluorinated azaheterocycle with DMAP leads to the formation of a fluoride salt. This salt, formed in situ, was used as a source of nucleophilic fluoride ion for the fluorination of a range of electrophiles. Several of the fluoride salts were converted to their more stable tetrafluoroborate or triflate analogues and characterised.

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9

Kennedy, R. J. "Copper-promoted nucleophilic aromatic substitution." Thesis, University of Kent, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355148.

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10

Haleem, Asad Bilal. "Crosslinking nucleophilic dyes on cotton." Thesis, University of Leeds, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250890.

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11

Salim, A. M. "Nucleophilic cleavage of organic disulphides." Thesis, University of Essex, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381243.

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12

De, Pascale Maria Egizia. "Asymmetric nucleophilic addition to vinylphosphonates." Thesis, King's College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407452.

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13

Maji, Biplab. "Reactivity parameters for understanding nucleophilic organocatalysis." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-148415.

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14

Husein, Maen. "Nucleophilic sulfonation in microemulsions and emulsions." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36814.

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The nucleophilic sulfonation of decyl halides and benzyl halides was carried out at 298.2 K in batches in o/w microemulsions and emulsions formed with the two-tailed cationic surfactants dioctyldimethylammomum chloride, R2(Me)2N +Cl-, or bromide, R2(Me) 2N+Br-. The effects of mixing, surfactant concentration and counterion, and reactant concentrations on the conversion of the halide were investigated. At the concentrations employed, phase separation occurred in most of the samples. Mixing did not affect the sulfonation of decyl halides, while it governed the sulfonation rate of benzyl halides. Chloride as the surfactant counterion reacted with the bromide and iodide halides to form an intermediate, decyl chloride, and a side product, benzyl chloride. At a fixed time, the conversion to the final product versus surfactant concentration displayed a broad maximum. The tendency of sodium decyl sulfonate to remain at the interface resulted in lower conversion with increasing decyl halide concentration, while the formation of a separate benzyl halide phase produced the same effect. Increasing the mole ratio sodium sulfite/halide reactant increased the conversion to the final product in a manner that supports the mechanisms of ion exchange with the surfactant counterions and a second order nucleophilic substitution.
A single-pseudophase and a three-pseudophase model described the sulfonation of decyl halides and benzyl halides, respectively. The three new assumptions employed in the model are: (1) the volume of the interfacial region varies only with the amount of surfactant added, (2) the oil-soluble reactant may be unavailable for reaction if there is insufficient surfactant to bind all of the decyl halide to the interface, or insufficient mixing to eliminate the benzyl halide phase, and (3) a single ion exchange constant accounts for the exchange of three different anions at the interface.

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15

Fraser, Georgina. "Ionic liquid effects on nucleophilic substitutions." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/17827.

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In this thesis we demonstrate a fundamental difference between nucleophilic substitution reaction mechanisms in ionic liquids versus conventional solvents. Reported herein are the effects of ionic liquid solvents on substitution reactions between a cationic electrophile and the chloride anion of various organic and inorganic salts. We have combined novel quantitative studies of the nucleophilic source [Cat]Cl with our studies of [C4C1im]Cl and compared their reactivities, k2. For the first time, Eyring activation parameters have been calculated for substitution reactions between charged species in ionic liquid solvents and reveal a hitherto unprecedented role of the cation in the transition state. The activation parameters (ΔH≠ and ΔS≠) suggest the reactivity of the chloride anion can be manipulated by varying the size and chemical nature of the cation, and also shed light on cation hydrogen bond donating effects. The superior ability of ionic liquid solvents to fully screen the charges of reactant ions is shown to break down as ions become larger, less charge dense and display a tendency to self-aggregate.

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16

Annandale, Michael Thomas. "NMR spectroscopic studies of nucleophilic attack on dinitroaniline herbicides, reactions of selected nucleophiles with trifluralin and benefin." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq22268.pdf.

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17

Tandon, Raman. "Tailor-Made highly nucleophilic pyridines for organocatalysis." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-157028.

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18

Nguyen, Huy Van. "Metallocene-Pyrrolidinopyridine Nucleophilic Catalysts for 1.V." Thesis, Queen Mary, University of London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.498184.

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19

Martin, Peter Arnold. "Nucleophilic substitution reactions of some polyhalogenated compounds." Thesis, Durham University, 1987. http://etheses.dur.ac.uk/6876/.

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Rate measurements for the reactions of a series of polyfluoro - and polychloro - pyridines with aniline and ammonia in 60/40 dioxan/water at 25ºC has shown that chlorine, when ortho and para to the position of attack, is activating with respect to fluorine, but at the position meta to the point of attack, chlorine and fluorine are virtually equivalent in their effect on reaction rate. The trifluoromethyl and nitrile groups were found to be activating relative to fluorine when ortho and para to the position of substitution and the nitrile group was thus found to be ortho/para directing. The ortho/para orienting effect of ring nitrogen was shown to be dominant in heterocyclic systems. It has been demonstrated for several different nucleophiles that nucleophilic attack in polyfluorinated heterocycles occurs so as to maximise the number of ortho and meta fluorines with fluorine being of little significance. Of the nucleophiles examined aniline and ammonia were found to be similar in their behaviour. Benzylamine however showed some propensity for substitution at positions ortho to ring nitrogen whilst N-methylaniline showed strong steric effects due to the N-methyl group, most notably when the heterocylic ring substituents were chlorine, trifluoromethyl and nitrile. Sodium was shown to have a 'salt effect' in the reactions of methoxide and phenoxide, and, a catalytic effect on the reactions of aniline affecting both the rate and position of substitution. The use of transition state, and molecular orbitals to explain the patterns of substitution is discussed. The trifluoromethylsilyl group was found to undergo nucleophilic attack at silicon and the series of mono, di and tri-fluoromethyl-pentafluorobenzenes were used to examine the concept of negative ion hyperconjugation.

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20

Hinch, Melissa Marie. "Catalytic asymmetric nucleophilic epoxidation of aliphatic enones." Thesis, University of Sheffield, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425622.

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21

Lau, J. C. Y. "The mechanism of nucleophilic substitution at silicon." Thesis, Open University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374491.

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22

Aspinall, Garreth Martyn. "An investigation of nucleophilic cleavage of siloxanes." Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396724.

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23

Lester, Roy P. "Catalytic activation of nitriles towards nucleophilic addition." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/28449/.

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The work presented in this thesis is focused on the development of a multifaceted approach to the catalytic activation of nitriles. To develop a versatile method for catalytic nitrile activation two probes were utilised; i) the development of a direct synthesis of allylic amides from the corresponding allylic alcohol and nitrile using a commercial platinum salt, together with a detailed mechanistic investigation into the process, ii) the direct synthesis of 2-bezoxazole from the corresponding 2-aminophenol and nitrile with the aid of a commercial platinum salt as well as the use of alcoholic solvents. In addition to nitrile activation a preliminary study on the application and further functionisation of 2-trichlorobenzoxazoles was undertaken. i) A novel multifaceted approach to the direct synthesis of allylic amides via the catalytic activation of di- and trichloroacetonitrile will be discussed. This one-pot methodology relies on the same platinum catalyst to activate a nitrile towards nucleophilic attack of allylic alcohol as well as activate the newly formed allylic imidate towards a [3,3]-sigmatropic rearrangement, which produced a number of allylic amides. In addition to the development of the one-pot allylic amide methodology a number of mechanistic studies including 1H, 13C{1H} and gas chromatography were under taken to better understand the process. ii) The second probe used to identify the versatility of this multifaceted catalyst approach to nitrile activation was the direct synthesis of 2-benzoxazoles. Within this study it was discovered that protic solvents were able to activate di- and trichloroacetonitrile efficiently towards nucleophilic attack of the nitrogen nucleophile. From this discovery a mild and effective synthesis of a variety of di- and trichlorobenzoxazoles was developed in which the solvent was acting as the activating agent towards nucleophilic attack. iii) Preliminary results will also be reported on the novel manipulation of the trichloromethyl moiety of benzoxazoles. Within this study two efficient methodologies for the selective synthesis of 2-(pyrrolidin-1-yl)benzo[d]oxazole and benzo[d]oxazol-2-yl(pyrrolidin-1-yl)methanone were developed from a single starting material. These results show a positive direction for the study into diversity oriented synthesis to form a number of different small molecules from a single starting material by altering the conditions of the reaction.

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24

Drees, Paul Frederick. "Secondary Isotope Effects of Nucleophilic Vinylic Substitution." W&M ScholarWorks, 1986. https://scholarworks.wm.edu/etd/1539625350.

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25

Whitmore, James Michael John. "Kinetic studies of nucleophilic displacement at heteroaromatic centres." Thesis, University of Kent, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386135.

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26

Jones, Craig Warren. "Nucleophilic aromatic substitution using supported copper(I) reagents." Thesis, University of York, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236184.

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27

Beaumont, Andrew J. "A study of some selective nucleophilic fluorination reactions." Thesis, University of York, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306248.

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28

Butler, C. "New routes to polyurathene ionomers by nucleophilic substitution." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/38251.

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29

Hepburn, Hamish Bruce. "Enantioselective rhodium-catalysed nucleophilic allylation of cyclic imines." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/17614.

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A highly enantioselective and diastereoselective rhodium-catalysed addition of potassium allyltrifluoroborates to cyclic imines is described within. By utilising rhodium-chiral diene complexes, a wide range of cyclic imines were successfully allylated in high yields and enantioselectivities. Using a variety of more highly substituted allyl reagents, additional stereocentres and further molecular complexity was achieved with good yields, enantioselectivities and diastereoselectivities. Investigations involving isomeric allyl species and deuterated allyl species provided results that gave mechanistic insight, leading to the proposal of a plausible mechanistic pathway and suggested the formation of interconverting allylrhodium intermediates. Furthermore, during these investigations, a highly interesting isomerisation of the allylrhodium intermediate was discovered. Such isomerisation led to the in situ formation of the more complex allylrhodium intermediates which led to complex products upon allylation with cyclic imines that would be difficult to synthesis via other methods. This isomerisation was found to occur for a range of cyclic imines and disubstituted allyltrifluoroborates, proceeding in good yields and diastereomeric ratios. Deuterium studies indicate it is probable that this isomerisation proceeds via a 1,4 rhodium migration and a plausible mechanism is proposed explaining both the connectivity of the products and the relative stereochemistry.

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30

Belknap, Ethan M. "Computational Model of the Nucleophilic Acyl Substitution Pathway." Wittenberg University Honors Theses / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=wuhonors1623251026132848.

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31

Iagrossi, Anna. "Stereochemical studies of reactions of phosphate and thiophosphate esters." Thesis, University of Leicester, 1988. http://hdl.handle.net/2381/33748.

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Nucleophilic substitution reactions involving phosphate monoesters have been investigated. Two general syntheses of O-alkyl or O-aryl [16O,18O] thiophosphate monoesters are reported. An independent and general method for the determination of the enantiomeric excess of isotopically chiral thiophosphate monoesters has been developed and the absolute configurations of the diastereoisomers of (2R)-O-(O-ethyl thiophosphoryl)-3, 4S-dimethyl-5S-phenyl-l,3,2-oxazaphos- pholidin-2-one have been assigned. The solvolysis of p-nitrophenyl [R-16O,18O] thiophosphate in ethanol gives rise to ethyl [16O, 18O] thiophosphate with a large degree of racemisation of configuration (~80%). This observation is consistent with the formation of a thiometaphosphate intermediate of finite life-time which is then trapped by ethanol with accompanying loss of stereochemical integrity. This study provides the first direct evidence for a monomeric thiometaphosphate in protic solvent. During the course of developing the stereochemical analysis, it was noted that O-ethyl thiophosphate reacts with cis-2-chloro-3, 4-dimethyl- 5-phenyl-l, 3, 2-oxazaphospholidin-2-one with ca. 10% inversion and 90% retention of configuration. This system also reacts with fluoride ion with complete loss of stereochemistry. Cis-2-chloro-3, 4-dimethyl-5- phenyl-l, 3, 2-oxazaphospholidin-2-one and the corresponding 2-thione are epimerised to the more stable trans isomers by pyridine and other nucleophilic catalysts. These reactions require an in-line exocyclic displacement at a phosphorus centre held in a five-membered ring. Nucleophilic substitution at di- and tri-esters have also been studied. The stereochemical course of the hydrolysis of the 1, 3, 2-dioxaphosphor- inan-2-one system involving good leaving groups such as chloride and fluoride occur with inversion of configuration via an in-line mechanism, whereas hydrolysis of this system involving poor leaving groups occurs with retention of configuration via a pseudorotation mechanism.

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32

Duff, Jack Lawrence. "Single electron transfer in nucleophilic reactions of substituted norbornanes." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/27444.

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33

Nguyen, René-Viet 1981. "Catalytic tandem nucleophilic addition for the synthesis of heterocycles." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115708.

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Classical methodologies for carbon-carbon bond formation often require stoichiometric amount of reagent to prefunctionalize a C-H bond. Such methods generate a lot of waste and are therefore not atom-efficient. On the other hand, the use of catalysts for the direct use of C-H bond without prior functionalization is a more desirable approach for carbon-carbon formation. For example, an overall addition reaction is 100% atom economical. This thesis focuses on the catalytic addition of the three types of C-H bonds (Csp-H, Csp2-H and Csp3-H) to unsaturated molecules such as conjugated dienes, imines and carbon dioxide to form heterocycles.
The first chapter describes the direct single addition of 1,3-diketones (Csp3- H bond) to conjugated dienes and enol ethers catalyzed by gold(III) chloride and silver(I) trifluoromethanesulfonate. The reaction is highly regioselective, although the overall yields are modest (up to 70%) due to the oxidative nature of the catalysts. Under certain conditions, the addition product undergoes a subsequent cyclization to form dihydrofurans. This tandem addition/cyclization reaction is catalyzed by trifluoromethanesulfonic acid and is discussed in the second part of the chapter.
The second chapter deals with the addition of phenol derivatives (C sp2-H bond) to conjugated dienes catalyzed by gold(III) chloride and silver(I) trifluoromethanesulfonate. The reaction affords dihydrobenzofurans via an intramolecular O-H cyclization. Investigation into the sequence of the reaction shows that the C-C bond is formed before the C-O bond.
The third chapter presents the addition of terminal alkynes (Csp-H bond) to imines catalyzed by cheap copper(I) iodide salt via a three-component coupling of salicylaldehyde derivatives, secondary amines and alkynes. Microwave irradiation is used which considerably shortens the reaction time and eliminate the use of solvents. Dihydrobenzofurans with an exocylic double bond are formed via an intramolecular O-H cyclization. The use of aliphatic alkynes molecules containing a heteroatom is critical to the success of the reaction.
Finally, in the last chapter, the addition of terminal alkynes (C sp-H bond) to carbon dioxide (catalyzed by gold(I) chlorotriphenylphosphine and silver trifluoromethanesulfonate) is applied to the synthesis of arynaphthalene lactones via a multicomponent coupling of phenylacetylene, CO2 and 3-bromo-1-phenyl-1-propyne.

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34

McCullagh, John Francis. "Chromatographic studies of nucleophilic substitution in cyano cobalt complexes." Thesis, Queen's University Belfast, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356946.

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35

Cozens, A. J. "Studies in heterocyclic-mediated nucleophilic displacements in aryl systems." Thesis, University of East Anglia, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370378.

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36

Drew, S. M. "Photochemical nucleophilic substitution reactions of quinones and related systems." Thesis, University of Leeds, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374182.

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37

Zhu, Fujiang. "Asymmetric acylation of alcohols by nucleophilic catalysis-synthetic studies." Thesis, University of Sheffield, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412248.

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38

Garzon, Sanz Miguel. "Developing nucleophilic nitrenoids for the synthesis of complex heterocycles." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/7060/.

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The combination of nucleophilic nitrenoids and gold-catalysis has rapidly emerged as a powerful tool in the assembling of different nitrogen-containing motifs. The research presented in this thesis describes the advances in the field and the exploration of pyrimidium \(N\)-heteroaryl aminides as building blocks in the formation of several fused imidazoheterocycles. From the initial discovery of this reaction and its application in the synthesis of imidazo[1,2-a]pyrimidines, the scope of this convergent gold-catalysed strategy has been adapted to allow the access to fourteen classes of biologically relevant structures. The proposed mechanism and optimisation will be discussed alongside the accommodation of a wide range of useful functionalities difficult to introduce by other methodologies.

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39

Davies, Christopher Alan. "A-aryl quaternary centres via asymmetric vicarious nucleophilic substitution." Thesis, Cardiff University, 2005. http://orca.cf.ac.uk/54560/.

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This dissertation first describes a new method for the formation of a-aryl lactams based on the Vicarious Nucleophilic Substitution reaction. The route involves the three-component coupling of a nitroarene, an a-phenylsulfanyl lactam and an electrophile. The process incorporates various electrophiles and various-substituted cyclic amides and has been developed for the most part using nitrobenzene. The process was also applied to a-phenylsulfenyl pyrazolidinones. The process also includes examples of amides possessing a removable nitrogen protecting group to give access to functionalised amides with a free NH group. Secondly, an asymmetric version of the VNS reaction is described. The diastereoselectrvity of the VNS-alkylation reaction of lactones was studied. For example using an a-phenylsulfanyl-Y-substituted butyrolactone, nitrobenzene and an alkyl halide, diastereoselectivities of greater than 7:1 were observed in some cases. The stereogenic centre at the y position is clearly able to exert considerable control in the generation of the new stereogenic centre at the a-position. The third area of research described involves capture of the intermediate VNS anion with aryl electrophiles. Activated electrophiles react in this way via an SnAt process. The VNS and SnAt reactions were combined to form an efficient one-pot three-component coupling process to give easy access to functionalised diarylmethanes. Reduction of the nitro group of selected products gave a quick and easy route to the oxmdole structural motif. The final chapter describes our attempts to react the intermediate VNS anion with unactivated aryl halides in a transition metal cross-coupling process. Unfortunately, we did not find conditions to effect the coupling of the anion derived from a VNS process with aryl halides. Nevertheless, the anion of nitrophenylacetates prepared via deprotonation participates in cross-coupling reactions with ease and provides an alternative way to prepare diarylmethanes. This has the potential to be extremely useful due to the lack of reports of nitroarenes in cross-coupling processes.

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40

Maza, Quiroga Ricardo José. "Nucleophilic boryl motifs and alpha-borylcarbanions: reactivity and trends." Doctoral thesis, Universitat Rovira i Virgili, 2021. http://hdl.handle.net/10803/673184.

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En el Capítol 2, coure(I) catalitza la ciclació borilativa de gamma-alquenil aldehids mitjançant una adició quimio- i regioselectiva de Cu-B sobre C=C, seguida d'una reacció intramolecular d'adició de Cu-C sobre C=O. Els productes s'han format amb diastereoselectivitat i un anàlisi computacional ha identificat els punts claus que determinen la quimio- i diastereoselectivitat observada. En el capítol 3, s'estudia la reactivitat dels compostos diborats amb diens 1,3 en un context lliure de metalls de transició. Unicament, l'addició de Na2CO3 sobre bis(pinacolat)diboro, en MeOH, permet la 1,4-hidroboració de 1,3-diens no cíclics i cíclics. La influencia electrònica del sustrat garanteix la hidroboración conjugada 1,4 versus la 1,2. Càlculs DFT mostran que la distribució de la càrrega en l'anió alílic intermedi governa la selectivitat en la 1,4-hidroboració, mentres que la configuració trans del diè determina la preferència pel producte alil-borilat E. En el capítol 4, s'estudia la química dels carbanions alpha-borilats, ja que mostren una gran diversitat i permeten la formació d'enllaços C-C eficients. La deficiència electrònica del centre borilat trisubstituit és responsable de l'estabilizació del carbanió, facilitant la seva formació i modelant la reactivitat. Es descriuen aspectes electrònics de la estructura i tendèncias reactives d'un conjunt ampli d'alpha-boril carbanions. Mitjançant estudis de DFT s'ha determinat un mapa de tendencies sobre la reactivitar nucleòfila dels carbanions alpha-borilats, variant la naturalesa del grup borilo, el número de grups borilo en el carbanió i la naturalesa del catió estabilizant. Aquest mapa de tendencies permet la selecció del sintó apropiat, en funció de la reactivitat objecte d'estudi.
egioselectiva de Cu-B sobre C=C, seguida de una reacción intramolecular de adición de Cu-C sobre C=O. Los productos se han formado con diastereoselectividad y un análisis computacional ha identificado los puntos clave que determinan la quimio- y diastereoselectividad observada. En el Capítulo 3, es estudia la reactividad de los compuestos diborados con 1,3-dienos en un contexto libre de metales de transición. La única adición de Na2CO3 sobre bis(pinacolato)diboro, en MeOH, permite la 1,4-hidroboración de 1,3-dienos no cíclicos y cíclicos. La influencia electrónica del sustrato garantiza la hidroboración conjugada 1,4 versus la 1,2. Cálculos DFT muestran que la distribución de la carga en el anión alílico intermedio gobierna la selectividad en la reacción de 1,4-hidroboración, mientras que la configuración trans del dieno determina la preferencia por el producto alil-borilado E. En el capítulo 4, se estudia la química de los carbaniones alpha-borilados, ya que muestran una gran diversidad y permiten la formación de enlaces C-C eficientes. La deficiencia electrónica del centro borilado trisustituido es responsable de la estabilización del carbanión, facilitando su formación y modelando su reactividad. Se describen aspectos electrónicos de la estructura y tendencias reactivas de un conjunto amplio de alpha-boryl carbanions. Mediante estudios de DFT se ha determinado un mapa de tendencias sobre la reactividad nucleófila de los carbaniones alpha-borilados, variando la naturaleza del grupo borilo, el número de grupos borilo en el carbanión y la naturaleza del catión estabilizante. Este mapa de tendencias permite la selección del sintón apropiado, en función de la reactividad objeto de estudio.
In Chapter 2, copper (I) catalyzes the borylative cyclization of gamma-alkenyl aldehydes through chemo- and regioselective addition of Cu-B to C=C and concomitant intramolecular 1,2-addition of Cu-C on the C=O. The products are formed in an exclusive diastereoselective manner and computational analysis identify the key points for the chemo- and diastereoselectivity observed. In Chapter 3, we study the reactivity of diboron reagents with 1,3-dienes in a transition-metal-free context. The sole addition of Na2CO3 to bis(pinacolato)diboron, in MeOH, allows the 1,4-hydroboration of cyclic and noncyclic 1,3- dienes. The electronic influence on the substrate guarantees the conjugated 1,4-hydroboration versus 1,2-diboration. DFTcalculations show that the distribution of charge in the allylic anion intermediate governs the selectivity toward 1,4- hydroboration, while the favored trans configuration in diene reagents determines the preference for the E allyl boronate products. In Chapter 4, we studied the chemistry of alpha-boryl carbanions since they show a remarkable diversity, and enable efficient C-C bond formation. The electron-deficient, trivalent boron center stabilizes the carbanion facilitating its generation and tunning its reactivity. We describe the electronic structure and the reactivity trends of a large dataset of apha-boryl carbanions. We use DFT-parameters for capturing their electronic and steric properties, computational reactivity towards model substrates, and crystallographic analysis within the Cambridge Structural Dataset. This study maps the reactivity space by systematically varying the nature of the boryl moiety, the substituents of the carbanionic carbon, the number of alpha-boryl motifs, and the metal countercation. Furthermore, we can classify the alpha-boryl alkylidene metal precursors into three classes directly related to their reactivity. This trend map aids the selection of the appropriate reactive synthon depending on the sought reactivity.

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41

Van, der Westhuizen Carl Johan. "Nucleophilic substitution reactions of α-haloketones : a computational study." Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/63346.

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This dissertation describes the computational modelling of reactions between α-haloketones and various nucleophiles. Nucleophilic substitution reactions of α-haloketones (also known as α- halocarbonyls in literature) are utilised in synthetic laboratories to obtain 1,2-disconnections; which are typically difficult to obtain otherwise. To gain insight into these reactions, DFT modelling was carried out in this project, with further understanding into these reactions being obtained using Quantum Fragment Along Reaction Pathway (QFARP) which is an extension of Interacting Quantum Atoms (IQA). The nucleophilic substitution reaction was modelled between α-bromoacetophenone (α- BrAcPh), to represent α-haloketones, and the common nucleophiles phenolate (PhO–) and acetate (AcO–). QFARP provided insight into the reactions which could not have been obtained with other computational approaches. It was shown that the reaction with AcO– results in greater destabilisation for the α-group of α-BrAcPh as compared to the reaction of PhO–, explaining the difference in activation energies for the reactions. Diatomic- and fragment-interactions provided awareness into the driving force of the reactions and showed how the hydrogens for the α-group of α-BrAcPh provide significant attractive interactions with the nucleophiles during the initial stages of the nucleophilic substitution reaction. Furthermore, reactions modelled between α-BrAcPh and MeO– was done, as experimental literature has reported the presence of two competing reactions: nucleophilic substitution and epoxidation. Modelling showed the two reactions have low activation energies which are comparable with another. Interestingly, the rate determining step for the epoxidation reaction is not the formation of the transition state structure but rather the rotational barrier which is required to allow the leaving group, bromine, to be trans to the carbonyl-O of α-BrAcPh. Previous reports indicated that the presence of an electron donating/withdrawing group on the phenyl ring of α-BrAcPh had a significant influence on the reaction rate and selectivity between the two reactions. These experimental observations correlated well with the modelling results when comparing the potential energy surfaces (PES) of the reactions. Analysis using QFARP was also applied to these reactions to gain a more fundamental understanding of the reactions and how they differ. While QFARP was not able to explain the selectivity with different substituents present, insight into the dominating interactions that are involved in the reactions was recovered.
Dissertation (MSc)--University of Pretoria, 2017.
Chemistry
MSc
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42

Clough, Robert Steven. "The synthesis of aromatic polyethers by aromatic nucleophilic substitution." Case Western Reserve University School of Graduate Studies / OhioLINK, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=case1057072167.

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43

Zhang, Lianhao. "Synthesis of perfluoro[2.2]paracyclophane and its nucleophilic substitutions." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0041102.

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44

Sohal, Gian Singh. "Reversible nucleophilic addition : a new approach to asymmetric catalysis." Thesis, University of Bath, 2001. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341684.

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45

Sawadjoon, Supaporn. "Palladium-Catalyzed Nucleophilic Substitution of Alcohols : Mechanistic Studies and Synthetic Applications." Doctoral thesis, Uppsala universitet, Syntetisk organisk kemi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-209541.

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This thesis deals with the palladium-catalyzed nucleophilic substitution of π-activated alcohols in which the C–O bond of a non-manipulated hydroxyl group is cleaved. The thesis is divided in two chapters describing two different catalytic systems. Chapter 2 describes a heterogeneous palladium-catalyzed transfer hydrogenolysis of primary, secondary, and tertiary benzylic alcohols to generate the corresponding aromatic hydrocarbons using formic acid as the hydrogen donor. A detailed mechanistic investigation of this reaction has been conducted that establish the kinetic order of each reaction component and also the deuterium kinetic isotope effects. This data provide a mechanistic picture that the hydride transfer from formic acid to palladium, and not the C–O bond cleavage, is involved in the rate-determining step and that a catalytic amount of a base promotes the transfer hydrogenolysis. Chapter 3 describes the development, mechanistic studies and synthetic scope of a homogeneous palladium-catalyzed amination of allylic alcohols. Isolation of the catalyst precursor and equilibrium studies of the palladium and π-acidic triphenylphosphite ligand show unique properties of this catalytic system. Stereochemical, kinetic, and kinetic isotope studies have been performed to provide insight into the mechanism of C–O bond cleavage of allylic alcohol and C–N bond formation catalyzed by the palladium complex. Interestingly, both O–H and C–O bond cleavages are involved in rate-determining steps.

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46

Cid, Torta Jessica. "Nucleophilic versus electrophilic boryl moieties: activation and application in catalysis." Doctoral thesis, Universitat Rovira i Virgili, 2013. http://hdl.handle.net/10803/129289.

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Els compostos de bortrivalent s’han considerat tradicionalment com a àcids de Lewis, preferint acceptar electrons més que donar-los en el curs de les reaccions, peròdarrerament han sorgit exemples a la bibliografia on el compost trivalent de bor presenta una reactivitat insòlita vers posicions electrofíliques. Aquest fet ens suggereix un nou context nucleofílic per als sintonsboril, que pot ser augmentat depenent dels substituents als quals estigui unit el bor. En aquesta tesi, volem mostrar una visió de les reactivitat soposades mitjançantl’estudi teòric de diferents compostos de bortri coordinats. A més a més també ens hem centrat en l’estudi de dues reaccions, la hidroboració trans no convencional on la unitat borilactuacom a electròfil i la -boració organo catalítica amb un diborà mixton la unitat boril actua com a nucleòfil.
Boron compounds have been traditionally regarded as “Lewis Acids” preferring to accept electrons rather than donate them in the course of their reactions, but current examples of unusual reactivity between tricoordinatedboranes and electrophilic sites suggest another conceptual context for the boryl moieties, based on their nucleophilic character which can be enhanced depending on the substituents on boron. In this thesis, we aim to show an overview of these opposite reactivities through the computational study of different trivalent boron compounds. Moreover, we have also focused our attention in the study of two reactions, the non-conventional trans-hydroboration where the boryl moiety is acting as an electrophile and the organocatalytic-boration with a mixed diboron reagent where the boryl moiety is acting as a nucleophile.

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47

Balan, Gayatri. "Studies on the nucleophilic substitution reactions of a dimeric cyclopentadienone." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/6265.

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Thesis (M.S.)--University of Missouri-Columbia, 2007.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on January 11, 2008) Includes bibliographical references.

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Duin, Marcel Adrianus. "Nucleophilic and electrophilic platinum compounds for C-H bond activation." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2004. http://dare.uva.nl/document/75218.

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49

James, Rachel Anne. "Nucleophilic substitution reactions of (alkoxymethylene) dimethylammonium chloride and cyclopropane methodology." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342180.

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50

Patterson, Richard. "Novel organofluorine chemistry : nucleophilic fluorinating agents and potential anticancer compounds." Thesis, Cardiff University, 2006. http://orca.cf.ac.uk/55525/.

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This thesis covers work investigating the effects of fluorine incorporation on the structure, biological activity, and NMR properties of anticancer chalcones as well as novel methods for the inclusion of fluorinated moieties into organic compounds. The first chapter looks at the use of silanes as carriers of small fluorinated nucleophiles which can be activated by fluoride anion catalysis to deliver such nucleophiles to organic electrophiles such as aldehydes. The synthesis of a group of such silanes and an assessment of their reactivity towards aromatic aldehydes is described. The second and third chapters describe the synthesis and compare the structures and biological activities of four series of chalcones; chapter two looks at chalcones which have non fluorinated groups (a nitrile group and an ethyl ester group) on the alpha position and chapter three looks at chalcones which have F and CF3 groups on that position. A comparison of the effects of substitution, at both the alpha position and on the B ring, on structure and cytotoxicity of these compounds is given. Several of the fluorinated chalcones were found to be highly cytotoxic and further assessment of their tubulin-binding properties was carried out. Chapter four looks at some unusual, long range fluorine-hydrogen coupling interactions which have been observed in the NMR spectra of certain types of chalcones. The effects of various substitutions and structural changes on these coupling patterns are examined. In addition a brief study into the dimerisation of chalcones is described. The final chapter looks at the use of FAR type reagents to generate asymmetric fluorinated amides using secondary chiral amines. Synthesis of a number of chiral amines praline and their addition, with limited success, to trifluorovinyl styrenes is discussed.

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