Dissertations / Theses: 'Methods of synthesis'

1

Thom, Catriona. "Synthetic methods directed towards the synthesis of rapamycin." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241117.

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Clark, Jonathan. "New synthetic methods towards the synthesis of taxanes." Thesis, University of Leicester, 1994. http://hdl.handle.net/2381/34051.

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This thesis is a continuation of previous work done in the Jenkins group to produce taxanes from glucose. The reactions investigated by R. Bonnert and J. Howarth are improved upon to enable the large scale synthesis of the diol (1). After the successful protection of (1) with two tert-butyldiphenylsilyl protecting groups the benzylidene ring was opened by bromination with N-bromosuccinimide. This compound then underwent fragmentation with zinc metal to open the acetal ring and yield the highly functionalised key intermediate chiral cyclohexane (2). This aldehyde was then reduced with sodium borohydride and protected with a triethylsilyl group. The alkene side chain underwent ozonolysis cleanly followed by the addition of lithium-2,2,3,3-tetramethyl-bromocyclopropane. The cyclopropane addition was improved upon by the addition of cerium trichloride. Compounds (3) were isolated from this reaction and a series of studies were done to test the viability of these compounds to undergo further reactions, in particular to rearrange to give dienes. Compounds with bromine in were found to rearrange and those with chlorine in did not. It is believed that most of this work was done with compounds containing chlorine, although at the time this was not realised. Detailed spectroscopic studies verified the stereostructures as those desired for taxanes at the key chiral centres. Alternative sugar routes were also considered and this work gave rise to a new Robinson reaction on a carbohydrate, to give compound (4). Unfortunately this compound was found to have the wrong stereostructure for the synthesis of taxanes from it.

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3

Nimkar, Sandeep Krishnaji. "Studies in asymmetric synthesis: Development of new synthetic methods for syntheses of natural products." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186538.

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The research, to be discussed in three chapters, involves the development of new synthetic methods which are applicable to the total synthesis of many natural products. Chapter 1: As a part of a program to synthesize new auxiliary agents for asymmetric synthesis, we have prepared a structurally rigid acetal from norbornene in three chemical steps. This enantiomerically pure acetal has been used for resolution of racemic α-hydroxy esters and might be applied as a chiral auxiliary for diastereoselective reactions. Chapter 2: The Calicheamicin and Esperamicin antibiotics have shown remarkable biological activity as site-specific cleaving agents of double stranded DNA. The oligosaccharide portion of these molecules plays an important role in the site specificity. We have developed synthetic methodologies that allow synthesis of the deoxyaminosugar components of these antibiotics and can be extended to synthesize unnatural amino sugars for structure-activity studies. Chapter 3: Enantiomerically pure cyclopropyl ketones, which are available via chiral ketals, are very useful for syntheses and diastereoselective manipulations of common and large rings. This method has been extended to introduce up to four contiguous chiral centers in a common ring. This extension could be useful for the syntheses of complex natural products.

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Elgie, Kerry J. "Combinatorial methods in porphyrin synthesis." Thesis, University of Essex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.517452.

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Underwood, Joseph Mark. "New methods in ring synthesis." Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277494.

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Wonnacott, Anne. "New methods for spiroketal synthesis." Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/38192.

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7

Ho, Hoi Tong Lawrence. "New methods in chiral synthesis." Thesis, University of Bath, 1999. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301557.

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Knight, J. "New synthetic methods for the synthesis of #BETA#-lactam antibiotics." Thesis, University of Southampton, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373921.

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9

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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Wingstrand, Erica. "New Methods for Chiral Cyanohydrin Synthesis." Doctoral thesis, KTH, Kemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10205.

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This thesis deals with method development in asymmetric catalysis and specifically syntheses of enantioenriched O-functionalized cyanohydrins. The first part describes the development of a method for the synthesis of O‑alkoxycarbonylated and O-acylated cyanohydrins. Ethyl cyanoformate and acyl cyanides were added to aldehydes in a reaction catalyzed by a chiral dimeric Ti-salen complex together with a tertiary amine. High yields and enantioselectivities were in most cases obtained. Mechanistic studies were performed and a reaction mechanism was proposed. The second part describes a method in which the undesired minor enantiomer in a Lewis acid–Lewis base-catalyzed acylcyanation is continuously recycled into prochiral starting material. Close to enantiopure O‑acylated cyanohydrins were obtained in high yields. The third part deals with asymmetric acylcyanations of ketones. Acetyl cyanide was found to add to α‑ketoesters in a reaction catalyzed by a chiral Lewis base. Yields up to 77% and 82% ee were obtained. The final part describes an enzymatic method for high-throughput analysis of O‑acylated cyanohydrins. The enantiomeric excess and conversion were determined for products obtained from a number of aromatic and aliphatic aldehydes.
QC 20100818

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James, Eurig Wyn. "Electromicrobial methods in synthesis and analysis." Thesis, Aberystwyth University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342992.

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Pillainayagam, Terence Anthony. "New methods in tetramic acid synthesis." Thesis, Loughborough University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416685.

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O'Neil, Ian Anthony. "Novel methods in natural product synthesis." Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/38124.

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Kero, Ida. "Ti3SiC2 synthesis by powder metallurgical methods." Licentiate thesis, Luleå tekniska universitet, Materialvetenskap, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17858.

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The MAX phases constitute a group of ternary ceramics which has received intense attention over the last decade due to their unique combination of properties. The Ti3SiC2 is the most well studied MAX phase to date and it has turned out to be a promising candidate for high temperature applications. It is oxidation resistant, refractory and not susceptible to thermal shock, while at the same time it can be machined with conventional tools which is of great technological importance. Most attempts to synthesize bulk Ti3SiC2 have involved pure titanium in the starting powder mixtures, but Ti powder is oxidising and requires an inert atmosphere throughout the synthesis process which makes the procedures unsuitable for large scale production. The aim of the first part of this study was to delineate the influence of sintering time and temperature on the formation of Ti3SiC2 from a starting powder which does not contain pure titanium. Titanium silicon carbide MAX phase was synthesised from ball milled TiC/Si powders, sintered under vacuum for different times and temperatures. After heat treatment the samples were evaluated using scanning electron microscopy (SEM) and x-ray diffraction (XRD). This study showed that TiC was always present in the final products whereas TiSi2 was an intermediate phase to the Ti3SiC2 formation. The highest amount of Ti3SiC2 was achieved for short holding times of 2-4 hours, at high temperatures, 1350-1400¢ªC. More elevated temperatures or extended times resulted in silicon loss and decomposition of Ti3SiC2. In the second part of this study the sintering reactions and the mechanisms of formation of Ti3SiC2 were investigated by x-ray diffractometry, thermodilatometry, thermogravimetry, differential scanning calorimetry and mass spectrometry. TiC/Si powders of the different ratios; 3:2 and 3:2.2, were heated to different temperatures under flowing argon gas in a dilatometer and examined by XRD. The TiC/Si powder samples of the ratio 3:2 were further investigated by the other thermal analysis methods. The results confirmed the presence of the intermediate phase TiSi2. From 1500¢ªC silicon evaporation and MAX phase decomposition were observed, and the results show that the MAX phase formation may be concurrent with the melting of silicon. TiC was always present in the final products, either as a reactant or as a decomposition product. The extra silicon of the 3:2.2 TiC/Si powder significantly increased the Ti3SiC2 conversion and no intermediate phases were observed for this powder mixture. The Si of these samples did not melt or evaporate, and only minor decomposition was observed even at 1700¢ªC. These results indicate that the silicon content of the initial powder mixture is decisive to the reaction mechanisms of the sintering process.

Godkänd; 2007; 20070523 (ysko)

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15

Roper, Kimberley Ann. "New flow chemistry methods for organic synthesis." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607846.

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Nichols, John Richard. "Synthetic methods involving 2-imidazolines." Thesis, University of Nottingham, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236028.

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Doores, Katie J. "Novel methods for the synthesis of glycoimmunological probes." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670149.

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18

Damkaci, Fehmi. "Methods for stereoselective synthesis of glycopyranosylamide linkage." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/21.

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Thesis (Ph.D.) -- University of Maryland, College Park, 2004.
Thesis research directed by: Chemistry. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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Kero, Ida. "Ti₃3SiC₂ synthesis by powder metallurgical methods /." Luleå : Luleå tekniska universitet/Tillämpad fysik, maskin- och materialteknik/Materialteknik, 2007. http://epubl.ltu.se/1402-1757/2007/34/.

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20

Maesano, Maria Grazia. "Silsesquioxanes : alternative approaches and methods of synthesis." Thesis, Open University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437783.

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21

Wood, Steven Gregory. "Objective Test Methods for Waveguide Audio Synthesis." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/853.

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Acoustic Physical Modeling has emerged as a newer musical synthesis technique. The most common form of physical modeling synthesis in both industry and academia is digital waveguide synthesis. Commercially available for the past thirteen years, the top synthesizer manufacturers have chosen to include physical modeling synthesis in their top of the line models. In the area of audio quality testing, the most common tests have traditionally been group listening tests. While these tests are subjective and can be expensive and time-consuming, the results are validated by the groups' proper quality standards. Research has been conducted to evaluate objective testing procedures in order to find alternative methods for testing audio quality. This research has resulted in various standards approved by the International Telecommunication Union. Tests have proven the reliability of these objective test methods in the areas of telephony as well as various codecs, including MP3. The objective of this research is to determine whether objective test measurements can be used reliably in the area of acoustic physical modeling synthesis, specifically digital waveguide synthesis. Both the Perceptual Audio Quality Measure (PAQM) and Noise-To-Mask Ratio (NMR) objective tests will be performed on the Karplus-Strong algorithm form of Digital Waveguide synthesis. A corresponding listening test based on the Mean Opinion Score (MOS) will also be conducted, and the results from the objective and subjective tests will be compared. The results will show that more research and work needs to be done in this area, as neither the PAQM nor NMR algorithms sufficiently matched the output of the subjective listening tests. Recommendations will be made for future work.

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22

Modak, Arghya. "Novel methods in glycosaminoglycan and proteoglycan synthesis." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:e7b6f5bb-58fe-45d1-8b23-48486e14c050.

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Glycosaminoglycans (GAGs) in general and heparin/heparan sulfate in particular are implicated in various biological functions by interacting with various protein partners. To elucidate the structure activity relationship (SAR) of these carbohydrate chains, considerable efforts towards the synthesis of these complex molecules have been made. Because of the heterogonous structure of these highly negatively charged molecules, a general approach towards synthesis of these molecules has not been possible. The central objective of this thesis was to develop a generic modular approach for the synthesis of defined thiomimics of heparin and heparan sulfate. Specifically we sought to utilize the unsaturation developed at the non-reducing end of heparin/heparan sulfate oligosaccharides by the action of lyases, for thiol-ene radical reaction to generate defined thiomimics of heparin Chapter -2 Thiol-ene radical reaction on model substrates The thiol-ene radical reaction on endocyclic double bonds in sugar molecules was initially established on protected model substrates and more importantly on deprotected model substrates in aqueous conditions. This demonstrates the first example of radical reaction in aqueous conditions for glycosylation between two carbohydrate substrates. Chapter-3 Towards building S-linked heparin and heparan sulfate mimics using thiol-ene chemistry The thiol-ene radical glycosylation strategy established on model substrates was utilized on both non-sulfated and sulfated building blocks of heparin/heparan sulfate to build novel thiomimics of heparin/heparan sulfate. The labile sulfate groups of heparin were found to be compatible with the reaction conditions. Initial biological studies done with the synthesized thiomimics did not show significant binding activity, probably due to the small size of the synthesized mimics. Chapter -4 Glycosyltransferase utilization for heparin thiomimic synthesis Natural glycosyltransferases were investigated for extension of the carbohydrate backbone of the thio mimics. Specifically, it was shown by MS for the first time that glucuronyltransferase can accept a thio mimic with unnatural stereochemistry as an acceptor.

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Watson, Christopher. "Development of new methods for peptide synthesis." Thesis, University of Edinburgh, 1994. http://hdl.handle.net/1842/14647.

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The preparation and evaluation of a number of carboxylic acid protecting groups is reported. The preparation of aspartic acid side chain esters of 9-anthracenylmethanol, 1-(9'-anthracenyl0-3-methylbutan-3-o1, 1-4(4'-fluorophenyl)-2-methylpropan-2-o1, dibenzosuberol and 4-methyl-2,6,7-trioxobicyclo[2.2.2]octane are described. The conversion of these into suitably protected N^α- Fmoc derivatives for the solid phase synthesis of peptides has been carried out and the comparison with established protection strategies is discussed. Model compounds of these derivatives have been prepared which have enabled an evaluation to be carried out of the stability of these systems to acidic and basic hydrolysis.

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Tatton, Matthew R. "New methods for the synthesis of aromatic compounds." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:52a95189-d8ea-432f-aefd-4f9ae7ef996a.

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Introduction The introduction describes the importance of arylamine compounds to society and provides a brief overview of the methods available for their synthesis. The application of metathesis catalysis to the de novo synthesis of heteroaromatic compounds is also described. Results and discussion The first section describes efforts towards the de novo synthesis of arylamines using a cross metathesis/oxidation protocol to form a 1,5-unsaturated dicarbonyl followed by an amine mediated cyclisation. The scope with respect to the 1,5-unsaturated dicarbonyl and amine is covered as well as the utility of some of the products. The section concludes with a modification of the Bohlmann Rahtz pyridine synthesis to furnish arylamines. The next section describes the applications of our methodology to the synthesis of naphthylamines, specifically using the palladium catalysed α-arylation reaction. A discussion of the α-arylation reaction is included as well as our efforts to explore the scope of the reaction. The third section follows our efforts to apply this methodologyy to the synthesis of five benzo[c]phenanthridine alkaloids including the first reported synthesis of maclekarpine B and C. The final section concludes with a discussion of our efforts towards the de novo synthesis of furans bearing a benzylic stereocentre.

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Collins, Beatrice Samora LeFanu. "New catalytic methods and strategies for chemical synthesis." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648556.

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Kumari, P. "New methods for the conjugation of peptides." Thesis, University of Liverpool, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.279720.

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27

Bonnert, Roger Victor. "New synthetic methods in an approach to taxinine." Thesis, University of Leicester, 1987. http://hdl.handle.net/2381/34018.

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A series of studies were undertaken directed towards the synthesis of taxinine. As part of these studies the need arose for a stepwise synthesis of a highly substituted butadiene from an aldehyde. The initial approach used the Peterson elimination to control the regio-chemistry in the formation of tri- and tetra-substituted dienes. The generality of this method appeared to be hampered by the basicity of 2-lithio-2-trimethylsilyl propane, which was required to undergo nucleophilic attack at an aldehyde. A study of the Diels-Alder reactions of a 3-alkyl-2,4-penta-l,3-diene and a 3-alkyl-4-methyl-penta-1,3-diene showed the former to react more efficiently. A deuterium labelling experiment eliminated the degeneracy of this diene in a 1,5-hydrogen shift as a reason for its increased reactivity. A more reliable route to the preparation of highly substituted butadienes was attained using the highly nucleophilic 2-lithio-2-phenyl- seleno-propane reagent. This route was used to prepare a triene system which underwent an intramolecular Diels-Alder reaction to enable the preparation of the taxane model compound 8,12,15,15-tetra- metllyltricyclo[9. 3. 1 .03,8] pentadec-ll-en-2-one which has the same stereochemistry and methyl group substitution as the naturally occurring taxanes. Attempts were then made to prepare taxinine using a carbohydrate derivative. A key step in the route to taxinine involved a Robinson annulation of a carbohydrate derived ketone. Alkylations of a carbohydrate derived enolate were studied initially. The Robinson annulation was then carried out using 3-trimethylsilyl-3-buten-2-ol and the enolate derived from methyl 4,6-O-benzylidene-3-deoxy-3-C- methyl-D-arabino-hexapyranosid-2-ulose.

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Youn, Jinsuop. "Methods and Strategies for Synthesis| (a) New methods for highly functionalized quinolines, (b) Synthetic studies toward Adriatoxin B, and (c) Total synthesis and structure assignment of Nosperin." Thesis, Yale University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3582180.

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This thesis describes the development of methods and strategies inspired by three natural products: the well-known anti-malarial quinine, the ladder polyether adriatoxin B, and nosperin – a natural product with unprecedented combinations of biosynthetic origins.

Chapter 1 details a novel method for constructing highly functionalized quinolones by CH-bond activation. This short, efficient, and scalable synthetic route begin C-H activation of aromatic carbonyl with Ru catalyst, oxime formation, and Beckmann rearrangement initiated LA is developed. This new method can be applied to synthesis of complex natural product including quinolines or small molecules in drug discovery.

Chapter 2 investigates plans for a total synthesis of Adriatoxin B and methodologies for ladder polyether compounds. Specific developments include a Ti-based subunit coupling method for pyran containing compounds, a ring-expansion reaction from pyrans to the 7-membered ring (oxepane), and from an oxepane to an oxocane (8-membered ring). In addition a new route for the synthesis of the cis-1,3-dimethyl pyran ring found in polyethers has been developed.

Chapter 3 provides a full story of the total synthesis and structure assignment of nosperin. Nosperin, known as a metabolite in symbiosis of lichen (Peltigera membranaces) and microorganism (Nostoc sp. cyanobacterium), was initially reported in 2013 with two unassigned stereocenters. A highly convergent synthetic route for Nosperin and its diastereomers has been developed that proceeds in 18 steps longest linear sequence. This synthesis provides the absolute and relative stereochemistry of the natural product, includes a revision of relative stereochemistry in the proline domain, and establishes the stereochemistry of the polyketide domain.

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Tšubrik, Olga. "New methods in the synthesis of multisubstituted hydrazines /." Online version, 2006. http://dspace.utlib.ee/dspace/bitstream/10062/481/5/tsubrik.pdf.

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Semenyuk, Andrey. "Novel Methods for Synthesis of High Quality Oligonucleotides." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7172.

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Chen, Xiaochun. "IMPROVED METHODS FOR PHTHALOCYANINE AND NAPHTHALOCYANINE CHROMOPHORE SYNTHESIS." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/195463.

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It has been demonstrated that the structural characteristics of phthalocyanines (Pcs) are critical to their performance in technological applications such as optical limiting, photodynamic therapy (PDT), organic field-effect transistors (OFETs), and organic photovoltaic (OPV) devices. The work in this thesis describes improved methods of substituted Pc and naphthalocyanine (Nc) synthesis addressing some currently encountered problems including: 1) chromophore aggregation and low solubility; 2) the need for selective synthesis of asymmetric Pcs; (3) a lack of general methods for producing Pc materials with structural diversity.Chapter 1 provides a concise review on three major advantages of using Pcs as OPV materials: near-IR absorption, self-organization in mesophase resulting in conductive columnar aggregates, and self-assembly at the supramolecular level to form complex nanostructures. In addition, Pc-based heteroarrays which have potential use for OPV and Pc-based dye sensitized solar cells (DSSC) are also discussed.Chapter 2 describes the synthesis and structural characterization of dendritic Ncs. As a continuation of previous work regarding non-aggregated Pc dendrimers, the site isolation effect of dendrons on Nc chromophores was studied by UV-vis spectroscopy. It was found that installation of higher generation dendrons not only enhanced the solubility of Nc cores in common organic solvents, but also resulted in non-aggregated Ncs in both solution phase and the solid state.Chapter 3 reports a synthetic strategy employing "click" chemistry to produce a family of structurally diverse Pcs. Octaalkynyl substituted Pcs have been prepared as a platform for the incorporation of various azides as peripheral functionalities. One of the Pc derivatives bearing photo-cross-linkable cinnamate residues has proven useful for the fabrication of robust cross-linked photopatterned and imprinted nanostructures.Chapter 4 discusses the synthesis of asymmetrical Pcs with six solubilizing groups and one hydroxyl group on the periphery through the "ROMP-Capture-Release" method. Further modification of the pendent hydroxyl group with sebacoyl chloride demonstrated that the unmasked hydroxyl site was reactive as a nucleophile, thus opening the possibility for intimately grafting Pcs onto inorganic substrates TiO2.Chapter 5 details the synthesis of asymmetric clickable Pcs bearing six alkyne groups and one hydroxyl group on the periphery. "ROMP-Capture-Release" was initially attempted, but it was found that the alkyne groups had to be TIPS-protected in order to avoid cross-metathesis during the "ROMP" reaction. However, the overall yield and efficiency of the TIPS-involved "ROMP-Capture-Release" route was so low that the large quantity of material required for device fabrication could not be obtained. Therefore, an alternative direct synthesis of the asymmetrical Pc by statistical condensation of two phthalonitriles was finally chosen. Pure asymmetrical hexaalkynyl-monohydroxy Pc was obtained after multi-stage column chromatography. Click reactions of this compound with several azides were also carried out.Chapter 6 summarizes the results presented in Chapters 2-5 and outlooks on some future directions that current research may follow.

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Green, Joseph Jacob. "Multiframe restoration methods for image synthesis and recovery." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284110.

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This dissertation is concerned with multiple-frame (multiframe) reconstructions using imagery acquired in dynamic imaging environments. Through several interesting examples, we address and relate the key concepts of information weighting, channel diversity and multiframe processing in the context of producing high resolution estimates from severely degraded imagery. For the problem of space object identification, we look at methods for preprocessing a collection of atmospheric turbulence-degraded short-exposure images to improve the resolving power of estimation algorithms. Specifically, we examine the performance of using frame selection to extract the least degraded subset of images from an ensemble for processing. Several measures of image quality are compared against idealized standards to demonstrate their relative effectiveness for ranking highly the least degraded image frames. We also examine the resolving implication of removing additive background noise, resulting from the sky and telescope. Specifically, we show that background compensation acts as a defacto restoration of the compact object support and leads to furthering the resolving power of estimation algorithms. In the context of dilute aperture imagery, we look at methods for inducing channel diversity into a collection of measurements. With a diverse image set, we compute estimates using both a joint multiframe objective and an aggregated objective. We then examine the implication of using joint or aggregate objectives in any estimation algorithm from a set-theoretic standpoint. Finally, we extend the classic Wiener filter for the multiframe case. The resulting formulation demonstrates that the appropriate weighting of image data allows for the worst frames to be included while improving the restoration. We discuss how this contradicts the earlier idea of frame selection and relates the multiframe Wiener filter to the dual information theoretic concept of "water-filling".

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33

Weekes, Ashley A. "New methods for synthesis of substituted 2-phenylbenzothiazoles." Thesis, Cardiff University, 2010. http://orca.cf.ac.uk/54377/.

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In recent years, substituted 2-arylbenzothiazoles have emerged as an important pharmacophore with a number of possible diagnostic and therapeutic applications. An example of this is provided by the simple 2- 4- aminophenyl benzothiazole series which has shown both exquisite antitumour activity and potential as a PET tracer in non-invasive imaging of Alzheimer's disease. Although there are documented procedures for their synthesis, the majority refer to those benzothiazoles unsubstituted in the benzothiazole ring and involve the use of harsh reaction conditions, and chromatographic purification. In this work a simple method for the rapid access to a range of 2- phenylbenzothiazoles both substituted and unsubstituted in the benzothiazole ring is reported, importantly the method described requires no chromatographic purification. A simple one-step synthesis to 2-phenylbenzothiazoles unsubstituted in the benzothiazole ring is described whereby the desired product was made in high yield and with a short reaction time under either thermal or microwave irradiation of a variety of benzaldehydes and 2-aminothiophenol using sodium metabisulfite as a mild oxidant in DMSO. The methodology was extended to the synthesis of biologically relevant 2- phenylbenzothiazoles substituted on the benzothiazole ring, starting from the appropriately substituted 2-aminophenyldisulfide. Under thermal conditions, a small diverse library of compounds was obtained in short reaction times with no chromatographic purification necessary. The synthesis of a number of 2-phenylbenzothiazoles either substituted or unsubstituted in the benzothiazole ring is also reported by polymer-supported synthesis, utilising polymer-supported triphenylphosphine and p- toluenesulfonic acid as catalysts for the reaction. Biological evaluation was undertaken on four cancer cell lines, namely, A549, LoVo, MCF-7, and PC3, with A549 and MCF-7 the most active. Although no exquisite activity was found, as these compounds contain either or both a carbon and fluorine atom they have the possibility to be labelled with either a 1 C or 18F label and therefore have potential use in PET imaging.

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34

Brand, Tobias Gerhardus. "Synthesis methods for multi-band coupled resonator filters." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95910.

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Thesis (PhD)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: In this dissertation a number of techniques to design multi-band filters, with specific focus on coupled resonator implementations, is presented. Multi-band transfer functions are constructed from single-band transfer functions using frequency mapping methods. A general class of rational mapping functions is presented that can accommodate arbitrary bandwidth specifications. Multi-band circuits are synthesised directly from multi-band transfer functions and are obtained by applying reactance transformations to single-band prototype circuits. For the direct synthesis of multi-band filters from multi-band transfer functions coupling matrix synthesis methods are employed. The circuits that result from matrix synthesis methods tend to have topologies that are undesirable from a practical perspective and must be simplified using rotations of the coupling matrix. The synthesis of multi-band filters through reactance transformations is both simple and result in filters that have practical topologies for realisation as coupled resonator circuits. Multiple filters are designed using different design methodologies and different transmission line technologies to illustrate the various design possibilities. The designs include both all-pole and cross-coupled filters and employ single-layer stripline, multi-layer stripline as well as coaxial resonators as transmission line technologies for the implementations.
AFRIKAANSE OPSOMMING: In hierdie proefskrif word verskeie ontwerpstegnieke vir multi-band filters aangebied en word daar spesifiek klem gelê op filters wat as gekoppelde resoneerder strukture geïmplimenteer kan word. Multi-band oordragsfunksies word geskep uit enkelband oordragsfunksies deur gebruik te maak van wiskundige afbeeldingstegnieke. ’n Spesiale klas van rasionale funksies word voorgestel wat spesifiek gebruik kan word om multi-band funksies te skep wat ’n arbitrêre bandwydte spesifikasie het. Multi-band stroombane word direk gesintetiseer vanuit multi-band oordragsfunksies en word ook verkry deur die toepassing van reaktansietransformasies op enkelband stroombane. Vir die direkte sintese van multi-band stroombane vanuit multi-band oordragsfunksies word stroombane gesintetiseer as koppelmatrikse. Stroombane wat op hierdie wyse gesintetiseer word is geneig om topologieë te hê wat nie baie gesog is vanuit ’n praktiese perspektief nie en matriks rotasies word dan hier ingespan om die stroombane se topologieë te vereenvoudig. Die sintese van multi-band stroombane deur gebruik te maak van reaktansietransformasies is beide eenvoudig en lei tot stroombane wat praktiese topologieë het vir implimentering as gekoppelde resoneerder strukture. Die ontwerpsmoontlikhede wat die verskillende metodieke bied word geïllustreer deur die ontwerp van verskeie filters op verskillende maniere waar daar gebruik gemaak word van verskeie transmissielyn tegnologië. Die filter ontwerpe sluit filters in waar alle transmissienulle by oneidige frekwensies is, sowel as gevalle waar somige transmissienulle by eindige frekwensies is. Die filters word geïmplimenteer deur gebruik te maak van koaksiale resoneerders sowel as enkellaag en multilaag strooklyn.

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35

Azizian, Kaveh. "Optimum-synthesis methods for cable-driven parallel mechanisms." Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/29255/29255.pdf.

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36

Richards, Mark Ian. "Refined methods in solid (gel) phase peptide synthesis." Thesis, University of Wolverhampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343258.

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37

Gardner, Helen. "New methods for the synthesis of amino compounds." Thesis, University of Newcastle Upon Tyne, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357640.

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38

Chowdhry, Muhammad Irfan. "New methods for the synthesis of amino acids." Thesis, University of Exeter, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.479410.

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Peters, Jaime Louise. "Generalised synthesis methods in human health risk assessment." Thesis, University of Leicester, 2006. http://hdl.handle.net/2381/30474.

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40

Park, Jason (Jason Sun-Hyung). "Synthesis and error correction methods in gene fabrication." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/37961.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Biological Engineering Division, 2006.
Includes bibliographical references (leaves 56-59).
Gene Fabrication technology involves the development and optimization of methods relevant to the in vitro synthesis of any given target gene sequence(s) in the absence of template. The driving purpose of this field of research is to bring about the capability for on-demand fabrication of a DNA construct of arbitrary length and sequence quickly, efficiently, and cost-effectively. The first part of this document describes many of the important considerations in performing successful de novo gene synthesis from a survey of the literature as well as from our own work. Recommendations are made for a universally effective, robust, and simple protocol for potential users of gene synthesis, discussing important factors such as choice of protocol, source of commercial oligonucleotides, and polymerase choice. The second part of this document focuses on error correction. Reducing error rates is one of the main challenges in gene fabrication because high error rates preclude the possibility of fabricating long gene targets in a practical and economical manner. Improvements in error rates are essential for continued progress in the development of gene fabrication technology. I discuss the importance of error rate in gene synthesis from a practical standpoint and show results in the development of novel methods for the removal of errors from a pool of synthesized DNA.
by Jason Sun-hyung Park.
M.Eng.

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41

McMurray, Lindsay. "New catalytic methods and strategies for chemical synthesis." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607709.

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Mynett, Donna Maria. "New methods for organic synthesis on solid supports." Thesis, University of Cambridge, 1995. https://www.repository.cam.ac.uk/handle/1810/271988.

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43

Lampakis, Elias G. "Algebraic synthesis methods for linear multivariable control systems." Thesis, City, University of London, 1995. http://openaccess.city.ac.uk/19007/.

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The mathematical formulation of various control synthesis problems (such as Decentralized Stabilization Problem (DSP), Total Finite Settling Time Stabilization for discrete time linear systems (TFSTS), Exact Model Matching Problem (EMMP), Decoupling and Noninteracting Control Problems) via the algebraic framework of Matrix Fractional Representation (MFR) - i.e. the representation of the transfer matrices of the system as matrix fractions over the ring of interest - results to the study of matrix equations over rings, such as : A . X + B . Y = C , (X. A + Y . B =C) (1) A· X = B , (y. A = B) (2) A·X·B = C (3) A·X + Y·B = C, X·A + B·Y = C, A·X·B + C·Y·D = E (4). The main objective of this dissertation is to further investigate conditions for existence and characterization of certain types of solutions of equation (1) ; develop a unifying algebraic approach for solvability and characterization of solutions of equations (1) - (4), based on structural properties of the given matrices, over the ring of interest. The standard matrix Diophantine equation (1) is associated with the TFSTS for discrete time linear systems and issues concerning the characterization of solutions according to the Extended McMillan Degree (EMD) (minimum EMD, or fixed EMD) of the stabilizing controllers they define, are studied. A link between the issues in question and topological properties of certain families of solutions of (1) is established . Equation (1) is also studied in association with the DSP and Diagonal DSP (DDSP) for continuous time linear systems. Conditions for characterizing block diagonal solutions of (1) (which define decentralized stabilizing controllers) are derived and a closed form description of the families of diagonal and two blocks diagonal decentralized stabilizing controllers is introduced. The set of matrix equations (1) - (4) is assumed over the field of fractions of the ring of interest , ℛ , (mainly a Euclidean Domain (ED) and thus a Principal Ideal Domain (PID)) and solvability as well as parametrization of solutions over ℛ is investigated under the unifying algebraic framework of extended non square matrix divisors, projectors and annihilators of the known matrices over ℛ . In practice the ring of interest is either the ring of polynomials ℝ [s] , or the rings of proper ℝ_pr(s) and especially proper and stable rational functions R_op(s). The importance of R_op(s) is highlighted early in the thesis and further computational issues arising from its structure as an ED are considered.

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44

Gilles, Antonin. "Fast hologram synthesis methods for realistic 3D visualization." Thesis, Rennes, INSA, 2016. http://www.theses.fr/2016ISAR0005/document.

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L’holographie est souvent considérée comme la technologie de visualisation 3D la plus prometteuse, puisqu'elle fournit l'illusion du relief la plus naturelle et la plus réaliste possible. Toutefois, pour trouver application dans le domaine de la visioconférence ou de la téléprésence, les méthodes de génération numérique d'hologrammes doivent produire des scènes réalistes avec une forte illusion de profondeur, et ce en temps réel. Cette thèse se situe dans ce contexte et est organisé en deux parties. Dans la première partie de ce travail, nous avons proposé deux algorithmes de synthèse d'hologrammes permettant de se rapprocher du temps réel. Tout d'abord, nous avons développé une méthode combinant deux approches complémentaires: les approches point-source et wave-field. Alors que les méthodes de l'état de l'art réduisent la complexité de calcul de ces deux approches indépendamment, notre méthode tire parti de chacune d'entre elles. De cette manière, le temps de calcul de l'hologramme a été réduit de plus de 65% par rapport aux méthodes point-source et wave-field conventionnelles. Deuxièmement, nous avons cherché à accélérer cette méthode hybride en supprimant les redondances temporelles entre les trames consécutives d'une vidéo 3D. Pour chaque image, l'algorithme détecte les changements dans la scène et met à jour l'hologramme des points affectés. Étant donné que seules de petites régions de l'hologramme sont mises à jour, la charge de calcul est considérablement réduite, permettant le calcul d’hologrammes couleur à 60 images par seconde. Dans la deuxième partie de ce travail, nous avons proposé deux algorithmes afin d'améliorer la qualité visuelle des scènes. Tout d'abord, nous avons perfectionné la méthode hybride pour tenir compte des occultations dans la scène. Pour cela, nous avons conçu une méthode efficace pour le calcul de l'occultation d'une onde lumineuse par un point. Cette méthode reproduit les occultations sans augmenter de manière significative le temps de calcul de la méthode hybride originale. Enfin, nous avons proposé une méthode pour le calcul d'un hologramme à partir de données multivue-plus-profondeur (MVD) avec prise en compte des réflexions spéculaires. Selon cette méthode, la géométrie de la scène est reconstruite à partir des données MVD sous la forme d'un nuage de points, ce qui permet de n'utiliser que quelques projections de la scène. En outre, afin de tenir compte de réflexions spéculaires, chaque point de la scène est considéré avoir une émission différente selon les directions. Enfin, la lumière émise par la scène est propagée dans le plan de l'hologramme. Les résultats expérimentaux montrent que cette méthode reproduit tous les indices de la profondeur et l'illumination précise de la scène avec une complexité de calcul réduite
Holography is often considered as the most promising 3D visualization technology, since it can produce the most realistic and natural depth illusion to the naked eye. However, in order to have application in the field of videoconferencing or telepresence systems, hologram synthesis methods should be able to produce realistic 3D scenes with strong depth illusion in real-time. This thesis falls within this context and is organized into two parts. In the first part of this work, we investigated two novel algorithms in order to get closer to real-time computation. First, we designed a fast hologram calculation method by combining two approaches which complement one another: the point-source and wave-field approaches. Whereas previously proposed methods reduced the computational complexity of these approaches independently, our method takes advantages from both of them. By this way, the hologram calculation time has been reduced by more than 65% compare to the conventional point-source and wave-field methods. Second, we further accelerated this hybrid method by removing temporal redundancies between consecutive frames of a 3D video. For each video frame, the algorithm detects changes in the scene and updates the hologram of only affected scene points. Since only small regions of the hologram are updated at each video frame, this method allows the computational burden to be dramatically reduced, enabling the computation of colorful video holograms at 60 frames per second. In the second part of this work, we proposed two algorithms in order to enhance the visual quality of displayed scenes. First, we improved the hybrid method to take into account occlusions between objects in the scene. To this end, we designed an efficient algorithm for light shielding between points and light waves. Experimental results revealed that this method provides occlusion effect without significantly increasing the hologram calculation time of the original hybrid method. Finally, we proposed a hologram computation method from Multiview-plus-depth (MVD) data with rendering of specular reflections. In this method, the 3D scene geometry is first reconstructed from the MVD data as a layered point-cloud, enabling the use of only a few perspective projections of the scene. Furthermore, in order to take into account specular reflections, each scene point is considered to emit light differently in all the directions. Finally, light scattered by the scene is numerically propagated towards the hologram plane in order to get the final hologram. Experimental results show that the proposed method is able to provide all the human depth cues and accurate shading of the scene with reduced computational complexity

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45

Aboutayab, Karim. "Novel methods for the synthesis of functionalised indoles." Thesis, University of Sussex, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262319.

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The work in this thesis describes investigations into the development of a tandem radicallDiels-Alder reaction strategy for the construction of indole alkaloids. The synthesis of a key precursor, 2-[(4-methylphenyl)sulfonyl]indole, was investigated and involved two main· strategies: functionalisation of the indole ring using lithiation procedures and assembling the indole as a key step (chapter 2). A method based on the former strategy was deemed to be the most practical and delivered the desired product in moderate yields (35 - 45%). The viability of the first step of the proposed tandem radicallDiels-Alder strategy was investigated by examining the intramolecular addition of vinyl and aryl radicals to a sulfone substituted indole (chapter 3). These studies showed that the addition of sp2 centred radicals to substituted indoles was feasible (20 - 40%). A study using an acetylenic precursor also provided useful information about the relative rates of desulfonylation and radical addition to acetyleneS; de-sulfonylation is a competing process. An alternative tandem palladiumlDiels-Alder reaction was briefly examined, but was thwarted by capricious palladium catalysed cross coupling reactions. Further studies were carried out to extend the scope of the novel ipso substitution reaction (chapter 4). It was found that alkyl radical cyclisations proceed efficiently to give a new ~ethod for the synthesis of fused[1,2-a]indoles (30 - 84%). The feasibility of a related ipso substitution using phenylthio and phenylsulfinyl substituted indoles was also examined. It was found that these reactions are also successful, but proceed in reduced yields compared with the sulfones (24 - 51 %). These results could be attributed to the more favoured reaction of the electron rich carbon centred radical with the more electrophilic 1t bond. The thesis is concluded by a brief discussion of the mechanism of these cyclisations with the available experimental evidence supporting an addition! elimination pathway.

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46

Liao, Hongjing. "Reporting Credibility in Educational Evaluation Studies that Use Qualitative Methods: A Mixed Methods Research Synthesis." Ohio University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1426115203.

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47

Isgro, Francesco. "Geometric methods for video sequence analysis and applications." Thesis, Heriot-Watt University, 2001. http://hdl.handle.net/10399/495.

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48

Olsen, Christian Adam. "Development of methods for solid-phase synthesis of neuroactive polyamine derivatives /." Cph. : The Danish University of Pharmaceutical Sciences, Department of Medicinal Chemistry, 2004. http://www.dfh.dk/phd/defences/christianadamolsen.htm.

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49

Welch, Rosemary. "The development of new synthetic methods towards the synthesis of biologically active natural products." Thesis, University of Portsmouth, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292089.

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50

Khanizeman, Rabi'ah Nisha. "Studies towards the synthesis of bioactive natural products and development of new synthetic methods." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066644.

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Plus de la moitié des médicaments mis sur le marché entre 1981 et 2014 sont des produits naturels ou des dérivés. Ainsi, les structures des produits naturels sont une excellente source d'inspiration pour la découverte de nouveaux médicaments. L'introduction de cette thèse met en lumière le rôle important joué par les produits naturels en chimie médicinale. De plus, la préparation de produits naturels peut déboucher sur le développement de nouvelles méthodes de synthèse. Ainsi, au cours de cette thèse une approche synthétique de plusieurs produits naturels a été réalisée. Ces composés présentent des motifs clés tels que des amino-alcools 1,3, des diamines 1,3 ou un tétrahydropyrane. Les études synthétiques réalisées comprennent le développement de nouvelles méthodes pour accéder à ces structures. D'autre part, une réaction de Heck permettant l'accès à des précurseurs de tri-aryl éthylènes a été mise au point
It has been estimated that more than half of all approved drugs, from the period 1981 to 2014, are either natural products or their derivatives. This, thus, indicates that natural products (NP), together with natural product derived and natural product inspired structures are significant as sources for potential leads towards the discovery of new drugs. The introduction of this thesis thereby highlights the importance of natural products in the field of drug discovery. In addition, the introduction emphasizes on the importance of natural products as a field of research. This is as the synthesis of natural products can result in the development of new synthetic methods which can then be applied to a broader range of applications across the field of chemistry. This new information, thus, bridges a gap in the scientific knowledge and allows for progress in science. Therefore the content of this thesis describes the syntheses and development of new synthetic methods towards bioactive natural products containing 1,3-amino alcohol, 1.3-diamine, THP-ring as well as tri-aryl ethylene unit which represent the key themes of (+)-negamycin (Chapter 1), (-)-cernuine and (+)-cermizine D (Chapter 2), enigmazole A (Chapter 3) and tamoxifen (Chapter 4), respectively

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Dissertations / Theses on the topic 'Methods of synthesis'

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