Log in

Relevant bibliographies by topics / THF and THP synthesis / Dissertations / Theses

Dissertations / Theses on the topic 'THF and THP synthesis'

To see the other types of publications on this topic, follow the link: THF and THP synthesis.

Author: Grafiati

Published: 10 December 2022

Last updated: 29 January 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 dissertations / theses for your research on the topic 'THF and THP synthesis.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.

1

Spurr, Ian Bruce. "Total synthesis of cis-sylvaticin and synthetic studies towards the synthesis of adjacent THF-THF and THF-THP Annonaceous acetogenins." Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/173853/.

Full text

Abstract:

The total synthesis of potent antitumour agent cis-sylvaticin (1.100) has been completed. Notable steps included the alcoholytic kinetic resolution of epoxide 2.2, two permanganate promoted oxidative cyclisation reactions, a tethered RCM to unite the two major fragments and the use of P4 phoshazene base to install the butenolide precursor. Synthesis of adjacent THP-THF and bis-THF cores via cascade oxidative cyclisation reactions with permanganate is an attractive route to many Annonaceous acetogenins. Attempted synthesis of an adjacent THP-THF core and synthesis of an adjacent bis-THF core are discussed.

APA, Harvard, Vancouver, ISO, and other styles

2

Schröder, Sabine. "cis-THF- und cis-THP-Aminosäuren als Bausteine für Gramicidin A Hybrid-Ionenkanäle Synthese, Struktur- und Funktionsuntersuchung." Berlin Logos-Verl, 2005. http://deposit.ddb.de/cgi-bin/dokserv?id=2820897&prov=M&dok_var=1&dok_ext=htm.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Luscombe, Kirsty Nicole. "A novel approach to the synthesis of the FG fragment of pectenotoxin-4." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:e434af14-cc0d-4ecf-b60e-2ed635e48fb8.

Full text

Abstract:

The cobalt-catalysed oxidative cyclisation of 5-hydroxy alkenes has been demonstrated to be a powerful synthetic tool for the formation of trans-THFs with excellent diastereoselectivity. This thesis describes the utilisation of this methodology in the synthesis of the FG fragment of pectenotoxin-4, allowing the scope of the reaction to be further explored. Introduction: This section introduces the pectenotoxins, a family of structurally complex closed-chain polyether macrolides with promising biological activities. The isolation, structural elucidation, and biological properties of the pectenotoxins are reviewed, along with a summary of previous syntheses towards the FG fragment of pectenotoxin-4. In addition, the cobalt-catalysed oxidative cyclisation of 5-hydroxy alkenes and its application in synthesis is discussed. Results and Discussion: An outline of the synthetic strategy employed in this project and details of the novel retrosynthesis of the C31-C40 fragment of pectenotoxin-4 is described. The synthetic studies carried out towards the synthesis of the FG fragment of pectenotoxin-4 are discussed in detail, with the exploitation of a cobalt-catalysed oxidative cyclisation as the key step to form the trans-THF F-ring. Overall, the FG fragment, which contains six stereogenic centres, was achieved in 18 total synthetic steps (13 longest linear sequence).

APA, Harvard, Vancouver, ISO, and other styles

4

Uppal, Sukhjinder Singh. "Preparation of η³-allylmolybdenum complexes using cis-Mo(CO)₄(THF)₂ : application to the synthesis of methyl pseudomonate C." Thesis, University of Leeds, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275796.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Williams, Oliver M. H. "A novel route to trans-THFs and the synthesis of sylvaticin." Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:116fc7cd-5b5c-449d-b144-00a08af64926.

Full text

Abstract:

trans-2,5-Disubstituted-tetrahydrofurans (THFs) are a common structural motif in many biologically active natural products, particularly in the Annonaceous acetogenins. This thesis develops a new route for their synthesis and applies it to the total synthesis of the Annonaceous acetogenin sylvaticin. Chapter 1: Introduction – Synthetic routes to trans-2,5-substituted tetrahydrofurans This chapter reviews methods for the synthesis of trans-2,5-THFs that have been applied to natural products synthesis. Chapter 2: Results & Discussion – A Novel Route to trans-THFs The rearrangement of activated 2,5-disubstituted cis-THFs is reviewed and is developed into a new synthetic method for the synthesis of trans-THFs. The reaction proceeds via a hydride shift mechanism to form an oxonium ion. Intramolecular reduction by a tethered hydrosilane stereoselectively forms the trans-THF. The mechanism of the rearrangement is investigated with the use of different stereoisomers and a deuterium labelling study. A cross-over study is carried out which confirms the reaction occurs via the proposed hydride shift mechanism. Chapter 3: Introduction – The Annonaceous Acetogenins This chapter introduces the Annonaceous acetogenins, a biologically active class of natural products often found with THF rings in their structure. The three key areas for their synthesis are explored- the synthesis of the THF core, the synthesis of the butenolide ring, and their coupling. Chapter 4: Results & Discussion – The Synthesis of Sylvaticin The Annonaceous acetogenin sylvaticin is introduced, and its isolation in nature and biological activity reviewed. With the aid of a model system study to extend the scope of the reaction, the methodology developed in Chapter 2 is then applied to the synthesis of sylvaticin. The synthesis, the first to be reported, is completed in a total of 19 linear steps starting from commercially available tetradecatetraene. In order to prove the obtained structure is that found in nature, a comprehensive investigation is undertaken using Mosher ester derivatives and the synthesis of its bis-epimer, 4,36-epi,epi sylvaticin. Chapter 5: Experimental Full experimental procedures and characterisation of compounds are reported.

APA, Harvard, Vancouver, ISO, and other styles

6

Pingali, Aparna. "Synthesis and X-ray Diffraction Structures of 2-(2-thienylidene)-4,5-bis-(diphenylphosphino)-4-cyclopenten-1,3-dione and fac-BrRe(CO)3[2-(2-thienylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione]." Thesis, University of North Texas, 2005. https://digital.library.unt.edu/ark:/67531/metadc4942/.

Full text

Abstract:

Treatment of 4,5 bis-(diphenylphosphino)-cyclopenten-1,3 dione with thiophene carboxyaldehyde in dichloromethane, in the presence of molecular sieves results in a new heterocyclic compound, 2-(2-thienylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (ligand), with a high yield. This product was characterized by using both IR and NMR spectroscopic techniques and the solid-state structure of the ligand was determined using X-ray crystallography. When the ligand was treated with the solvent stabilized intermediate of ReBr(CO)5 with THF, a monomeric metal complex, fac-BrRe(CO)3[2-(2-thienylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione] was the result. The solid-state structure of the monomeric metal complex was determined using X-ray crystallography. Photolysis and thermolysis studies of the complex will be further explored.

APA, Harvard, Vancouver, ISO, and other styles

7

Mariniello, Katia. "Comparative study of synthesis and incorporation of omega-3 and 6- long chain polyunsaturated fatty acids by THP-1 and HT29 cells with a specifc focus on the influence of retinoids." Thesis, London Metropolitan University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.540612.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Simon, Binto. "The development of synthetic methodology for stereoselective synthesis of aminoglycosides." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/the-development-of-synthetic-methodology-for-stereoselective-synthesis-of-aminoglycosides(746860dc-9b11-41b9-8283-9201d5149cd9).html.

Full text

Abstract:

RNA is recognised as an important biomolecule involved in many broad cellular functions such as transcription, translation regulation and protein synthesis. Most pathogenic viruses replicate their genome as RNA during some stages in their life cycle. There is an urgent need to develop new methods to treat numerous viral diseases by targeting RNA and to understand the processes by which RNA-protein complexation can be inhibited. Our study focuses on the interactions between the HIV-1 Rev Responsive Element RNA (RRE) with a series of aminoglycosides developed jointly between our group in Manchester and GSK (USA). Even though a number of novel aminoglycoside have been explored previously, they are complex, large molecular weight compounds with low specificity, which limits their use as RNA recognition ligands and anti-viral drugs. The key problem is to be able to synthesise precursors by short, direct routes, avoiding significant detours caused by traditional carbohydrate protecting group strategies, while still delivering sterocontrol and opportunities to diversify. In chapter II we describe our efforts to synthesize the 6-glucosamine moiety (A-ring). A flexible synthesis of 6-aminoglucosamine derivatives can be accomplished in 5 steps using a totally regioselective enzymatic hydrolysis, controlled oxidation to sensitive but manageable aldehydes (hitherto rarely accomplished with a C-4 OAc), and reductive amination technology that allow for unprecedented diversification. In a different approach stereocontrolled synthesis of a model compound was achieved in 4 steps including a novel TEMPO oxidation and a one-pot oxidation/imine-reduction for the complete synthesis of the molecule.Chapter III describes our attempts towards the development of a robust stereoselective O-glycosylation strategy using Lewis acids. In pursuance of an efficient synthesis of our designed RNA binder target compound the stereoselective formation of the glycosidic linkage connecting the A-ring with the 2-DOS ring is an important step. This chapter also gives a general overview of the challenges involved in glycosylation followed by the strategies we employed to overcome some of these issues. We discuss our unusual stereocontrolled glycosylation in which, despite a neighbouring “participatory” group at C-2, the α-glycoside is delivered in high yield. This result implies that the reaction does not occur through a conventional neighbouring group participation.

APA, Harvard, Vancouver, ISO, and other styles

9

Stewart, Mark Richard. "The design and synthesis of synthetic receptors." Thesis, University of Leeds, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400852.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Kim, Charles. "Synthetic studies toward the synthesis of norrisolide /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2002. http://wwwlib.umi.com/cr/ucsd/fullcit?p3055785.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Fleary-Roberts, Nadia. "Towards the total synthesis of domoic acid and the isodomoic acids." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/towards-the-total-synthesis-of-domoic-acid-and-the-isodomoic-acids(a32fd085-8e09-47b5-b533-ef259b1ae8a2).html.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Phillips, Andrew. "Studies towards the total synthesis of patellazole B." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/269364.

Full text

Abstract:

The patellazoles are a family of marine polyketide natural products first isolated from Lissoclinum patella in 1988 by both the Moore and Ireland groups. They exhibit significant cytotoxicity against the HCT 116 human colon tumour cells. To date however, their full 3D stereostructure have yet to be elucidated, which has hindered their development as potential drugs, and hampered full investigation into their biological mechanism of action and has deterred total synthesis efforts. This thesis describes synthetic efforts towards Patellazole B, which exhibits the highest potency of the three main congeners. To fully elucidate the structure and renew interest in the patellazoles as anticancer compounds, we have developed a flexible and modular synthesis that aims to define the unknown stereocentres within the pertinent region and allow for rapid fragment union. Compound 36 has been chosen as an initial target for NMR comparison studies. The synthesis of all eight diastereomers of this macrocycle should aid determination of the four unknown stereocentres. Chapter 2 describes the synthesis of the C1–C12 fragment, focusing on the configuring of the C5 methyl stereocentre and the construction of the C7-C10 stereotetrad via a boron-mediated anti aldol with an in-situ reduction. In the third chapter, the synthesis of the C13-C19 fragment is outlined. A boron-mediated glycolate aldol has been used to install the C16-C17 anti stereochemistry and a substrate-controlled reduction at C15 delivered the hydroxyl with high diastereoselectivity. Studies into the C¬17¬ methylation are also described. Chapter 4 describes the synthesis of one possible diastereomer of the C20-C25 fragment, as a template for the preparation of the other 7 possible diastereomers. The route therefore employs only catalyst based control methods to install the three stereocentres, utilising a Sharpless asymmetric epoxidation and Evans aldol to construct the stereotriad. The 22R, 23S, 24S diastereomer has been initially chosen to investigate the later chemistry. Chapter 5 contains discussion of the ongoing work investigating fragment union and formation of the macrocycle. A Heck coupling reaction has been employed to construct the C19-C20 bond and a Suzuki coupling reaction has been developed to facilitate the C12-C13 bond formation. These two cross couplings have delivered the C1 - C25 fragment, 360, the final compound reported in this thesis, which is three steps away from the completed macrocycle and six from compound 36. The experimental procedures and spectroscopic characterisation of the synthesised intermediates can be found in Chapter 6 and the Appendix.

APA, Harvard, Vancouver, ISO, and other styles

13

Rivas, Fatima R. "Synthetic studies towards the total synthesis of norzoanthamine." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3221252.

Full text

Abstract:

Thesis (Ph. D.)--University of California, San Diego, 2006.
Title from first page of PDF file (viewed September 8, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.

APA, Harvard, Vancouver, ISO, and other styles

14

Rahn, Volker Siegfried. "Synthetic studies towards the total synthesis of (-)-alstonerine." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401724.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Wild, Mark. "Synthetic studies towards the synthesis of spongistatin 1." Thesis, Bangor University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310863.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Turvill, Michael W. "The synthesis of natural and synthetic colouring materials." Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280103.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Scott, Richard. "Synthetic approaches towards the synthesis of phorbol esters." Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314251.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Scott, Karen Ann. "Synthetic studies related to the synthesis of vincristine." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367067.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Spoors, Paul Grant. "New synthetic approaches towards the synthesis of morphine." Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330148.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Tang, Andrew. "Synthetic methodology towards the synthesis of sesquiterpene lactones." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612321.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

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

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

23

O'Riordan, Timothy Jeremiah Cornelius. "Synthesis of the pyrrolidinone core of oxazolomycin A." Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:298746d3-69df-47b9-8a83-7949df1c94dc.

Full text

Abstract:

This thesis describes the development of synthetic strategies towards the densely functionalised pyrrolidinone core of the polyene β-lactone-γ-lactam antibiotic oxazolomycin A. Chapter 1 The oxazolomycins The oxazolomycins, a unique class of biologically active molecules containing a spiro-fused β-lactone-γ-lactam ring system are introduced. The isolation, structural elucidation and biological properties of the oxazolomycins as well as those of the structurally related inthomycins are reviewed. Chapter 2 Previous syntheses The two total syntheses of neooxazolomycin and the synthetic approaches to the pyrrolidinone core of oxazolomycin A and KSM-2690 B are evaluated. Chapter 3 Project aims An outline of the synthetic strategy employed in this project and details of the novel retrosynthesis of the pyrrolidinone core of oxazolomycin A are discussed. Chapter 4 Synthetic studies towards the pyrrolidinone core of oxazolomycin A The synthetic studies carried out towards the pyrrolidinone core of oxazolomycin A are described in detail. The preparation of an advanced intermediate containing the five chiral centres, four of which are contiguous, was achieved in twenty steps as a single diastereomer and as a single enantiomer. Chapter 5 Synthetic studies towards the middle fragment of oxazolomycin A A novel synthetic approach to the diene fragment contained in oxazolomycin A is reported. The formal synthesis of a dienyl iodide, in four fewer steps than previously reported was accomplished. Chapter 6 Conclusions and future work A summary of the synthetic work reported in this thesis and proposals for future study are presented. Chapter 7 Experimental Full experimental procedures and characterisation of compounds are reported. Chapter 8 References A complete list of citations employed in the previous seven chapters is provided.

APA, Harvard, Vancouver, ISO, and other styles

24

Shah, Rushabh Surendra. "Total syntheses of the nakinadine alkaloids." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:c022e538-9ff8-4914-8c17-dc0b3ed1fbae.

Full text

Abstract:

This thesis is concerned with the development of methodology for the asymmetric syntheses of the nakinadine family of marine alkaloids and through these synthetic endeavours, seeks to confirm the structure and assign the relative and absolute configurations of these alkaloids for the first time.

APA, Harvard, Vancouver, ISO, and other styles

25

Davie, Rebecca. "Synthetic studies towards the synthesis of FR182877 : the ABC rings." Thesis, University of Nottingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406974.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Thominet, Olivier Gaston Andre. "Synthetic studies towards the total synthesis of the neocarzinostatin chromophore." Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1445755/.

Full text

Abstract:

The chromoprotein Neocarzinostatin (NCS) was the first isolated member of the so- called 'enediyne' class of antibiotics and was found to exhibit broad-spectrum antitumor activity. NCS was isolated in 1965 from the bacterium Streptomyces carzinostaticus and is made up of a 1:1 non-covalent complex of an extraordinarily reactive nine-membered ring epoxydiyne chromophore (NCS-C) tightly bound to a protein known as apo-NCS. The antitumor activity arises solely from the chromophore which acts as a DNA-cleaving agent initiated by radical hydrogen abstraction of a deoxyribose residue. The apoprotein protects, carries and delivers the chromophore offering potential as a novel, more selective drug delivery system. Our general strategy towards NCS-C involves the Michael addition of an epoxydiyne to a cyclopentenone followed by cyclisation via an aldol reaction. The enantioselective synthesis of the cyclopentenone fragment had already been synthesised within the group via enzyme-mediated kinetic resolution. The aim of this project is to report our current efforts to establish a general method for the synthesis of epoxydiynes in order to apply our own Michael/aldol sequence. Different routes to these epoxydiynes have been developed using a Sharpless asymmetric epoxidation. However, these have proven to be extremely difficult due to the formation of unstable intermediates which could not be processed to fully elaborated epoxydiynes. After considerable investigation, a concise and convergent approach to epoxydiynes was finally achieved on a multi-gram scale. This involves a diastereoselective addition of an allenyl zinc bromide to propargylic ketones/aldehydes followed by epoxide formation. This new protocol enables us to synthesise fully functionalised and stereochemically pure epoxydiynes including C-8 provides a very simple synthetic route to other functionalised epoxydiynes. Owing to the flexibility of our new method, epoxydiynes with different protecting groups can now be readily prepared enabling us to screen them in new Michael addition reaction studies.

APA, Harvard, Vancouver, ISO, and other styles

27

Blum, Janna Karen. "Broadening the enyzme-catalyzed synthesis of semi-synthetic antibiotics." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39528.

Full text

Abstract:

An alpha-amino ester hydrolase (AEH) applicable to synthesis of semi-synthetic antibiotics was cloned from the genomic DNA of Xanthomonas campestris pv. campestris sp. strain ATCC 33913. AEHs catalyze the synthesis and hydrolysis of alpha-amino beta-lactam antibiotics. The enzyme was characterized for thermodynamic and kinetic parameters. The enzyme shows optimal ampicillin hydrolytic activity at 25C and pH 6.8. The AEH enzymes have been shown to have excellent synthetic capability. Additionally, we demonstrated the first fully aqueous enzymatic one-pot synthesis of ampicillin direct from the natural product penicillin G eliminating the isolation of the intermediate 6-APA. Lastly, to improve the thermostability of the AEH a modified structure-guided consensus model of seven homologous enzymes was generated along with analysis of the B-factors from the available crystal structures of the known AEH from Xanthomonas citri. Our best variant, which is a quadruple mutant, E143H/A275P/N186D/V622I, which has a T_50_30, the temperature at which the half-life is 30 minutes, of 34C and 1.3-fold activity compared to wild-type. Overall, we have successfully improved the understanding of the AEH class of enzymes and applied a novel cascade application, demonstrating AEHs unique applicability in the synthesis of beta-lactam antibiotics. The improved thermostability will further improve the industrial relevance of AEHs.

APA, Harvard, Vancouver, ISO, and other styles

28

Sreekumar, Sanil. "Synthetic studies towards the total synthesis of lancifodilactone G." Thesis, University of Liverpool, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.569566.

Full text

Abstract:

This thesis presents our studies towards the first total synthesis of the novel anti- HIV agent lancifodilactone G, which has a highly unusual aliphatic enol. The first chapter provides a survey of architecturally diverse nortriterpenoids that were isolated from the Schisandraceae family. A proposed biosynthetic pathway for lancifodilactone G and closely related natural products provides a rationale for the formation of the consecutive 7/8/5 fused carbo cycles that are unique to Schisandra nortriterpenoids. Chapter 1 goes on to outline the reported strategies to access the core of lancifodilactone G and concludes with a retrosynthetic analysis proposed by the Evans group, which includes a biosynthetically inspired single-pot polycyclisation reaction. Chapter 2 describes the highly stereocontrolled synthesis of the eastern fragment (F-G rings) using transition metal-mediated Pauson-Khand reaction. This chapter also reviews the metal-mediated diastereoselective Pauson-Khand reaction directed by the stereogenic centre at C2, with the ample illustration to total synthesis. Attempted strategies for the assembly of the bicyclic cyclopentanone motif via a dienyl Pauson-Khand reaction of silicon- and oxygen- tethered diene-enes are presented. The failure of these strategies at different stages of the synthesis resulted in the exploration of a classical Pauson-Khand approach, which successfully furnished the eastern fragment. Finally, a second-generation synthesis is described which provided the fully functionalised eastern fragment with improved efficiency and overall yield. Chapter 3 discusses the successful synthesis of the western fragment (B-C rings) using a diastereoselective [4+3] cycloaddition strategy. Attempted strategies for the synthesis of the key 2,3-disubstituted furan derivative are presented, which was achieved via a hetero Pauson- Khand reaction. This chapter includes a brief account of the classical [4+3] cycloaddition reactions of furans using an in situ generated oxyallyl cation and also employing vinyl carbenoids in the metal-catalysed version. The review also highlights the application of the [4+ 3] cycloaddition reaction in the expeditious assembly of functionalised 7-membered rings that occur in a number of important biologically active natural products. The third chapter goes on to describe the application of these cycloaddition reactions in the synthesis of the fully functionalised western fragment of Lancifodilactone G. Chapter 4 describes a model study aimed at expediting the synthesis of the western fragment using a rhodium-catalysed allylic substitution reaction. A brief mechanistic discussion on unique aspects of the allylic alkylation reaction is illustrated. Chapter 4 concludes by outlining the coupling strategy for eastern and western fragments and the end game studies for the completion of the synthesis of lancifodilactone G.

APA, Harvard, Vancouver, ISO, and other styles

29

Dunn, Stephen Henry. "Total synthesis of norsegoline : synthetic approaches to the cystodytins." Thesis, University of East Anglia, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238806.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Pearson, David James. "Synthetic studies towards the total synthesis of popolohuanone E." Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267117.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Shen, Yue. "Design, synthesis and characterization of the synthetic yeast genome." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33182.

Full text

Abstract:

With the rapid development of DNA synthesis technologies, synthetic biology has made tremendous progress in the past 15 years, in particular for synthetic genomics. Synthetic genomics is a nascent field of synthetic biology, which aims to design new biological systems/organisms to satisfy human needs. Conventional synthetic biology focuses on the redesign, construction and modeling of biological parts, pathways or genomes that do not exist in nature, while synthetic genomics encompasses technologies that allow the generation of chemically synthesized larger parts of genomes or whole genomes, with simultaneous redesign of an organism's genetic material. Synthetic genomics is painting a blueprint for a new era of biology and holds great potential for a multitude of applications, such as pharmaceuticals, biofuels and rapid generation of vaccines against emerging diseases. Chapter One gives an introduction of the current state of the art and challenges of synthetic genomics and the objectives of this study. Chapter Two demonstrates the design and construction strategy of two megabase-long synthetic yeast chromosomes, SynII and SynVII. Chapter Three describes the full characterization of SynII and SynVII. Chapter Four introduces the SCRaMbLE (Synthetic Chromosome Rearrangement and Modification by LoxPsym-mediated Evolution) system and its application in SynII and SynVII. Taken together, this work demonstrates the utility of synthetic yeast for understanding biological systems and its potential for industrial applications.

APA, Harvard, Vancouver, ISO, and other styles

32

Oswald, Magalie Florence. "Novel synthetic methodologies for the synthesis of heterocyclic rings." Thesis, University of Sussex, 2010. http://sro.sussex.ac.uk/id/eprint/2348/.

Full text

Abstract:

Part 1. Synthesis of Stereodefined Heterocyclic Rings. We wish to report the development of novel methodology for the synthesis of stereodefined heterocyclic rings, which could be used for the synthesis of natural products containing for example tetrahydrofuran motifs, such as members of the pamamycin family. Due to their ambivalent properties, organoaluminium reagents can easily react with acetals by transfering an alkyl group after prior coordination with the substrates. This work has led to the development of a novel cascade reaction. It involves the reaction of acetals with trialkylaluminium reagents, which is followed by a cyclisation reaction, generating consequently tetrahydrofuran or tetrahydropyran rings. In addition, investigation towards the synthesis of pyrrolidines was also carried out. Part 2. Investigation and Development of a Novel Cascade Reaction. The Bergman cycloaromatisation reaction is based on the formation of a biradical intermediate species and has been, over the years, a constant source of inspiration for scientists. Continued efforts over the last 40 years permitted, among other things, a better understanding of the mode of action of the enediyne antibiotics, a class of natural compounds with exceptional biological activities. The Parsons group recently developed a novel cyclisation reaction, which also generates a biradical species, and which could, after being trapped with a suitable alkene, lead to the formation of tricyclic molecules containing heterocyclic cores. As a result, we wish to further investigate this novel reaction and develop a tandem reaction, involving this reaction combined with a Diels-Alder reaction in order to generate pentacyclic molecules, in one synthetic operation, and from an acyclic precursor.

APA, Harvard, Vancouver, ISO, and other styles

33

Vassilaras, Plousia E. "Alternative Synthetic Methodologies for the Synthesis of Organosilicon Compounds." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1310150433.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Audic, Alexandre. "Synthetic studies towards the total synthesis of hexacyclinic acid." Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/7790/.

Full text

Abstract:

In the first chapter of this thesis, published works found in the literature about hexacyclinic acid and FR182877 are reported and commented. A quick summary of the previous work done in the Prunet group is also described. In the second and third chapter, a more detailed account of the work undertaken during this PhD was given. Firstly, syntheses of two ABC tricycles incorporating tert-butyl and (trimethylsilyl)ethyl esters were undertaken. These syntheses include two key steps previously developed in the group, a diastereoselective Michael addition and a Snider cyclisation. Multiple conditions for the hydrolysis of the esters were attempted but none of them gave the desired product. The main part of this work is focused on the synthesis of a CDEF model and in particular about the development of the key step, the formation of a nine-membered ring. Several DEF fragments were synthesised in short synthetic sequences and as single isomers. Six different synthetic pathways were developed in total and a novel method, a Michael/elimination reaction, was found to be a very efficient way to close the desired medium-size ring. From the nine-membered ring, regioselective reduction and palladiumcatalysed allylic substitution led to the formation of the CDF tricycle. Final steps of the synthesis were fruitless and led only to decomposition. A synthesis of a chiral C-ring was also developed during this PhD. II Finally, another project was undertaken, not related to hexacyclinic acid. Methodology developed in the group for the diastereoselective formation of trisubstituted alkenes employing a temporary silicon-tethered ring-closing metathesis was extended to homoallylic alcohols. The first steps of the method were similar to the previous methodology but the end-game had to be modified in favour of an oxidation/reduction sequence to successfully obtain the desired products with the correct geometry. In the fourth chapter, procedures and analytical data for the synthesised compounds previously described are reported.

APA, Harvard, Vancouver, ISO, and other styles

35

Liu, Yifan. "Synthesis of the CDE & EFG ring systems of pectenotoxin-4." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:c531f0b3-4961-43e6-b7aa-c273df89a16f.

Full text

Abstract:

This thesis explores new synthetic routes for the formation of CDE & EFG fragments of pectenotoxin-4. Chapter 1: Introduction and Previous Work: This chapter reviews the discovery and biological activities of members of the pectenotoxin family. Two previous total syntheses are discussed, and previous work regarding the synthesis of ABC, E and FG fragments within the group is introduced. Chapter 2: Synthesis of the E Ring Fragment of Pectenotoxin-4: The synthesis of the E ring fragment is discussed. Key reactions include Negishi coupling and osmium mediated oxidative cyclisation. Chapter 3: First Generation Strategy for the Synthesis of the D ring: A simple model towards the D ring core was completed using alkyne-epoxide opening strategy. The application on a more sophisticated system was tested. Chapter 4: Second Generation Strategy for the Synthesis of the D ring: Sonogashira coupling was successfully tested as key step to unite two coupling partners; and further functionalisation towards the D ring skeleton was studied. Chapter 5: Third Generation Strategy for the Synthesis of the D ring: The new strategy including a Lewis acid assisted coupling and mercury mediated hydration of alkyne sequence was completed on a simple model. The application on a more sophisticated system was tested. Chapter 6: Synthesis of EFG Fragment of Pectenotoxin-4: Key Julia-Kocienski olefination between E ring fragment and FG ring fragment was examined. The further functionalisation of the resulting coupling product towards EFG fragment was finished. Chapter 7: Experimental: Full experimental procedures and characterisation of compounds are reported.

APA, Harvard, Vancouver, ISO, and other styles

36

Adams, Timothy C. (Timothy Cho). "Development of Epipolythiodiketopiperazine syntheses and the total synthesis of diketopiperazine alkaloids." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/97980.

Full text

Abstract:

Thesis: Ph. D. in Organic Chemistry, Massachusetts Institute of Technology, Department of Chemistry, 2015.
Cataloged from PDF version of thesis. Vita.
Includes bibliographical references.
I. The Development of Epipolythiodiketopiperazine (ETP) Syntheses Epipolythiodiketopiperazine (ETP) alkaloids represent a structurally complex and biologically potent class of secondary fungal metabolites and these molecules have been known since the 1930s. The biological activity of these molecules is quite potent and the modes of toxicity possessed by these agents involve the generation of reactive oxygen species (ROS) and direct manipulation of target proteins. The biosynthesis of these compounds has been the subject of active study and we have presented our own hypothesis how theses molecules are synthesized by fungi. Efforts to synthesize these alkaloids have been known since the late 1960 to early 1970s and all have highlighted the need to install the requisite disulfide bridge at a late-stage. The ETP motif is known to be notoriously sensitive as it is reactive towards bases and Lewis acids, and in photochemical and redox reactions. II. Development of ETP Syntheses for the Application of the Total Synthesis of (+)- bionectin A The concise and efficient total synthesis of (+)-bionectin A is described. Our approach to these natural products features a new and scalable method for erythro-[beta]- hydroxytryptophan amino acid synthesis and a new mercaptan reagent for the epipolythiodiketopiperazine (ETP) synthesis that can be unraveled under very mild conditions. The development of this new reagent was accomplished after exploring the acid promoted incorporation of different alkyl thiols into diketopiperazine diol substrates. III. Concise Total Synthesis of (+)-Luteoalbusin A The first total synthesis of (+)-luteoalbusin A is described. Our concise and enantioselective synthesis began from the simple starting materials L-alanine and Ltryptophan. Transformations central to our route include a highly regioselective Friedel- Crafts indolization that can be performed on multi-gram scale, as well as a highly diastereoselective oxidation and thiolation. Moreover, this divergent synthesis features a common aminothioisobutyryl intermediate that can be utilized to construct (+)- luteoalbusin A. The spectral data obtained from the synthetic samples confirmed the assigned structure for this natural product.
by Timothy C. Adams.
Ph. D. in Organic Chemistry

APA, Harvard, Vancouver, ISO, and other styles

37

Sedehizadeh, Simon. "Towards the total synthesis of domoic acid and the isodomoic acids." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/towards-the-total-synthesis-of-domoic-acid-and-the-isodomoic-acids(6a1a5ea8-f5a5-4185-8222-5d3486165ac9).html.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Vigliensoni, Martin Augusto. "Touchless gestural control of concatenative sound synthesis." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104846.

Full text

Abstract:

This thesis presents research on three-dimensional position tracking technologies used to control concatenative sound synthesis and applies the achieved research results to the design of a new immersive interface for musical expression. The underlying concepts and characteristics of position tracking technologies are reviewed and musical applications using these technologies are surveyed to exemplify their use. Four position tracking systems based on different technologies are empirically compared according to their performance parameters, technical specifications, and practical considerations of use. Concatenative sound synthesis, a corpus-based synthesis technique grounded on the segmentation, analysis and concatenation of sound units, is discussed. Three implementations of this technique are compared according to the characteristics of the main components involved in the architecture of these systems. Finally, this thesis introduces SoundCloud, an implementation that extends the interaction possibilities of one of the concatenative synthesis systems reviewed, providing a novel visualisation application. SoundCloud allows a musician to perform with a database of sounds distributed in a three-dimensional descriptor space by exploring a performance space with her hands.
Ce mémoire de thèse présente une nouvelle interface pour l'expression musicale combinant la synthèse sonore par concaténation et les technologies de captation de mouvements dans l'espace. Ce travail commence par une présentation des dispositifs de capture de position de type main-libre, en étudiant leur principes de fonctionnement et leur caractéristiques. Des exemples de leur application dans les contextes musicaux sont aussi étudiés. Une attention toute particulière est accordée à quatre systèmes: leurs spécifications techniques ainsi que leurs performances (évaluées par des métriques quantitatives) sont comparées expérimentalement. Ensuite, la synthèse concaténative est décrite. Cette technique de synthèse sonore consiste à synthéthiser une séquence musicale cible à partir de sons pré-enregistrés, sélectionnés et concaténés en fonction de leur adéquation avec la cible. Trois implémentations de cette technique sont comparées, permettant ainsi d'en choisir une pour notre application. Enfin, nous décrivons SoundCloud, une nouvelle interface qui, en ajoutant une interface visuelle à la méthode de synthèse concaténative, permet d'en étendre les possibilités de contrôle. SoundCloud permet en effet de contrôler la synthése de sons en utilisant des gestes libres des mains pour naviguer au sein d'un espace tridimensionnel de descripteurs des sons d'une base de données.

APA, Harvard, Vancouver, ISO, and other styles

39

Moore, Christopher Gareth. "Studies towards the synthesis of ptilomycalin A and synthetic analogues." Thesis, Bangor University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310923.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Long, Yun Oliver. "Synthetic studies toward the total synthesis of Zexbrevin and Jatrophatrione /." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488195633520712.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Baas, Tracey Lynn. "The design, synthesis, and characterization of template assembled synthetic proteins /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/11561.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Al-zaidi, Bashir Yousif Sherhan. "The effect of modification techniques on the performance of zeolite-Y catalysts in hydrocarbon cracking reactions." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/the-effect-of-modification-techniques-on-the-performance-of-zeolitey-catalysts-in-hydrocarbon-cracking-reactions(6f64393c-ea13-4ec4-85d3-60e650e26be7).html.

Full text

Abstract:

Mankind makes extensive use of crude oil to fuel its insatiable demands for energy and hydrocarbon derivatives. The refining of crude oil is based on a process known as cracking, where long-chain hydrocarbons are systematically broken into smaller chain hydrocarbons known as fractions with each fraction allowing for the production of a specific material. The maximum efficiency of cracking can be achieved in the petroleum refining processes by controlling the operating parameters of the units, and over the years many studies have attempted to optimize the cracking conditions such as temperatures, pressures and the use of a variety of catalysts to reach maximum productivity. Catalysts such as the Y-type zeolite catalysts are often used because their acidity and thermal stability makes them an ideal cracking catalyst; however the developments of enhanced catalytic properties for zeolite-Y catalysts are essential to increase the production yields. Optimization of the Y-type zeolite catalyst is the focus of this research and accordingly the synthesis, characterization, modifications and catalysis have been studied in depth. A review of the literature has shown that there are three main techniques used to improve the zeolite properties following the synthesis process; (Cation exchange, Dealumination and Desilication), since the crystalline structure of a Y-type zeolite is prepared from an alkaline aluminosilicates gel. However, the literature focuses mainly on the reaction variables used in the modifications. As such this study focuses on the effects of treatment processes on the composition, behaviour and catalytic properties of the synthesized Y-zeolite framework. Laboratory experimental data has confirmed that a synthesis process using 24 h aging for crystal nuclei at 25 °C and 18 h crystallization time for crystal growth at 100 °C produced the desired zeolite NaY morphology, and NaNH4Y zeolite forms with various cation contents (3, 1.5 and 0.5 wt% Na+) were obtained by subjecting the NaY form to a multi-stage ion exchange using 0.5 M NH4NO3 at 80 °C, while the HY form was obtained by the calcination of NH4Y form under high temperature. Calcination temperatures above 450 °C were shown to indicate a removal of the framework hydroxyl groups via dehydroxylation, which led to a collapse of zeolite-Y structure, whereas raising the level of Na+ inside the zeolite lattice throughout the calcination was led to a delay in the starting point of the dehydroxylation region as confirmed via TG and DSC-analyses. This finding was also used in the preparation of the USY form by steaming the HY form, as the former is a traditional zeolite-Y form utilized in the refining units. It was found that Na-ions hindered the extraction of Al-atoms from the Y-lattice thus reducing the rate of dehydroxylation, and minimising rapid contraction of the unit cells and Y-structure collapse, which helped make a rigid structure and a more resilient lattice for steaming at high temperature. In addition, analyses data confirmed that the extraction of EFAl-species from the USY-structures using an EDTA chemical treatment led to an increase in the acidity of treated catalyst and the introduction of mesopores. Lower lattice Si/Al ratio and larger porosity were also found using the dealuminated-desilicated rather than the desilicated-dealuminated leaching method in the treatment of both Y and USY structures via dislodgement of both Si and Al-atoms in NaOH and HCl solution. Cracking was performed on deactivated catalysts (450 °C) in a PFTR using nC7 in N2 at 325 - 425 °C and W/F = 22 - 44 g.h.mol-1, and confirmed that the tuned steaming/leaching conditions succeeded in modifying the catalytic properties of the in house made catalysts, as they possess superior performance when compared to the industrial catalysts typically used.

APA, Harvard, Vancouver, ISO, and other styles

44

Dadehbeigi, Nazanin. "Investigation of the role of the mTORC1 signalling pathway in growth and productivity of industrially-relevant GS-CHO cells." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/investigation-of-the-role-of-the-mtorc1-signalling-pathway-in-growth-and-productivity-of-industriallyrelevant-gscho-cells(b7820f57-2023-4667-830d-53ce1fe7eb76).html.

Full text

Abstract:

Understanding the molecular mechanisms that govern productivity and growth of recombinant host cells is essential to devise informed approaches to increase commercial viability and availability of biopharmaceuticals. This work has focused on the roles of the mammalian target of rapamycin complex 1 (mTORC1) signalling pathway in CHO cells, the most widely used expression system in the biopharmaceutical industry. mTORC1 is a master regulator of cell growth, protein synthesis and metabolism in response to availability of nutrients, oxygen and growth factors. Therefore, it was hypothesised that increased activity of mTORC1 enhances growth and productivity of recombinant CHO cells. The study of a recombinant GS-CHO cell line in the serum-free suspension batch culture indicated a gradual decrease in the activity of mTORC1, as defined by the decreased extent of site-specific phosphorylation of two widely ascribed downstream target proteins (ribosomal protein S6 kinase 1 (S6K1) and 4E-BP1, an inhibitor of translation initiation). The decline in the activity of mTORC1 paralleled decreased growth rate, recombinant protein specific productivity and global protein translation. To further clarify the role of the mTOR pathway in cell growth and protein production, cells in batch culture were treated with rapamycin, a specific inhibitor of mTORC1. Treatment with rapamycin stalled the growth of the CHO cell line transiently, but recombinant protein specific productivity, longevity of batch culture, and final antibody titre were greater than control. Rapamycin addition produced discriminating effects on downstream signalling targets, implicating distinct roles for these targets in control of growth and protein synthesis. Engineering the mTORC1 pathway by overexpression of specific components of this pathway (S6K1 and Rheb) generated increased growth and extended viability. Greater proliferation was not associated with improved productivity suggesting highly proliferative phenotypes that prioritise cell growth over synthesis and secretion of recombinant antibody in the recombinant GS-CHO cells examined. Therefore, the engineering of mTORC1 pathway may be beneficial to increase robustness or adaptation to stressed conditions (such as serum- free suspension growth, low nutrition availability and hypoxia).

APA, Harvard, Vancouver, ISO, and other styles

45

Mears, Paul. "Approaches towards the synthesis of the 20-deoxybryostatins and their 20,20-difluorinated analogues." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/approaches-towards-the-synthesis-of-the-20deoxybryostatins-and-their-2020difluorinated-analogues(82de5040-e32f-45fb-9537-8a5eaed7c67b).html.

Full text

Abstract:

This thesis describes approaches towards the synthesis of 20-deoxybryostatins and 20,20-difluorobryostatins. Towards the 20-deoxybryostatins, a route previously developed within the group was followed with a protecting group change designed to prevent problems encountered with a late-stage deprotection. To this end, (R)-pantolactone was transformed through to dimethyl (4S,6R,8R)-[4-(para-methoxybenzyloxy)-10-hydroxy-6,8-O-isopropylidine-3,3-dimethyl-2-one] phosphonate which was subsequently subjected to a Horner-Wadworth-Emmons condensation with (5R,E)-6-(4-methoxybenzyloxy)-5-triethylsilyloxy-3-(2’-triisopropylsilyloxyethylidene)hexanal. The reactions of the resulting enone through to the advanced intermediate allyl [(4R,6R)-6-((S)-2’-(4-methoxybenzyl)oxy-5-{(2’’S,6’’R)-6’’-(4-methoxybenzyloxymethyl)-4’’-[2-triisopropylsilyloxyeth-(Z)-ylidene]-tetrahydropyran-2’’-yl}-3,3-dimethyl-4’-oxopentyl)-2,2-dimethyl-1,3-dioxan-4-yl]-acetate are described, and this compound corresponds to a C1-C16 northern bryostatin fragment. A synthetic route to 20,20-difluorobryostatins was begun by the synthesis of three 3,3-difluoro-2-hydroxytetrahydro-4H-pyrans which started from an indium-mediated coupling of 3-bromo-3,3-difluoro-1-propene with an aldehyde. A strategy was employed which culminated in the preparation of 3,3-difluoro-2-hydroxy-2-(3-methylbut-1-en-3-yl)-4-(E)-methoxycarbonylmethylenetetrahydro-4H-pyran which corresponds to a C16-C23 20,20-difluorobryostatin southern fragment. Of particular interest is the selectivity observed in the reaction of α,α-difluoroketones with a stabilised Wittig reagent. The indium-mediated coupling was extended to include the first example of the coupling of a 2-alkyl substituted bromide.

APA, Harvard, Vancouver, ISO, and other styles

46

Schubert-Rowles, Richard. "The synthesis of mycolic acids." Thesis, Bangor University, 2010. https://research.bangor.ac.uk/portal/en/theses/the-synthesis-of-mycolic-acids(569faf84-2c7b-412d-a8ec-457ea6bb1100).html.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Lando, Alisa. "The Design and Synthesis of a First Aid Smart Fabric and Synthetic Studies Towards the Total Synthesis of Torilin." Thesis, Boston College, 2013. http://hdl.handle.net/2345/3235.

Full text

Abstract:

Thesis advisor: Marc L. Snapper
Chapter 1: The design of a novel first aid smart fabric that is linked to a biologically active molecule through an event specific cleavable linker is described. Successful functionalization of a cellulose filter paper fabric mimic and the synthesis of a linker which is potentially selectively cleavable in the presence of blood have been achieved. Chapter 2: Synthetic studies towards the total synthesis of Torilin, a sesquiterpene guaiane natural product with interesting biological activities are described. The synthesis of the hydroazulene core of Torilin is accomplished through a cyclopropanation/ Lewis acid mediated fragmentation of a highly functionalized polycyclic system which is rapidly accessed through the intramolecular cycloaddition of cyclobutadiene
Thesis (MS) — Boston College, 2013
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry

APA, Harvard, Vancouver, ISO, and other styles

48

Baker, David Bawden. "Applications of the Heck reaction for the syntheses of substituted pyridines and β,β-disubstituted vinyl Weinreb amides : studies towards the syntheses of inthomycin B and inthomycin C." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:09765f4e-83b9-4bb6-9130-7da3520752e6.

Full text

Abstract:

The Heck reaction has become a fundamental reaction for synthetic organic chemists over the last half century and is utilised heavily in the fine chemical industry and for natural product synthesis. This thesis describes some of the applications of the Heck reaction to modern day organic synthesis. Introduction: This section presents an overview of the Heck reaction starting from its conception during the late 1960s to present day understanding. A variety of ligand classes are described along with commonly accepted catalytic cycles for their activity during the reaction. Results and Discussion: In the first part of the thesis, the use of a cross-metathesis/Heck reaction protocol to synthesise a range of 2,4,6-trisubstituted pyridines is described. Attempts were made to expand the scope of the methodology by employing vinyl Weinreb amides, but this proved unsuccessful for the synthesis of pyridines. Nevertheless, the Heck reaction on vinyl Weinreb amides worked efficiently and the scope of this arylation was explored. Following on, the functionalisation of the Weinreb amide products was studied to generate a range of enone products, some of which would be difficult to synthesise via direct Heck reaction on the respective precursor enone. In the second part of the thesis, previous syntheses of inthomycin B and inthomycin C are described. The synthesis of inthomycin B and inthomycin C were then attempted using an unprecedented Mukaiyama aldol/cross-metathesis based approach to generate the triene core of both natural products.

APA, Harvard, Vancouver, ISO, and other styles

49

Gatland, Alice Elizabeth. "Palladium-catalysed enolate arylation in the synthesis of isoquinolines." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:f106760d-2375-4d56-81b2-faa6ee96cabc.

Full text

Abstract:

Chapter 1. Introduction Scientific background on the development of homogeneous palladium-catalysed cross coupling reactions, focusing on the α-arylation reaction of enolates and its application to the synthesis of heteroaromatic compounds. The classical syntheses of isoquinolines are discussed, followed by an account of modern methods for their synthesis, including the recent α-arylation-based methodology developed by the Donohoe group. Chapter 2. Results and Discussion 2.1 Studies towards the development of a palladium-catalysed, C–H activation-based α arylation reaction of ketones, resulting in a C–H bromination/α-arylation sequence for the synthesis of isoquinolines and isoquinoline N-oxides. 2.2 The one-pot, four component coupling of a ketone, an acetal protected ortho-bromobenzaldehyde or ketone, an electrophile, and an ammonia source is described. This protocol, which ultimately provides C4 functionalised isoquinolines, is later extended to a novel α,α heterodiarylation protocol to furnish C4-aryl isoquinolines. 2.3 It is shown that the synthesis of 3 aminoisoquinolines can be achieved via the α arylation of nitriles. tert-Butyl cyanoacetate can act as a substitute for primary alkyl nitriles, with sequential α-arylation, in situ functionalisation, decarboxylation and cyclisation reactions provide C4 functionalised 3 aminoisoquinolines. 2.4 The synthetic utility of the α arylation based methodology for isoquinoline synthesis is exemplified by the total synthesis of the alkaloid berberine in 68% yield over five steps. This is followed by syntheses of pseudocoptisine, palmatine, dehydrocorydaline, and an unnatural fluorine containing analogue, in yields of 46%, 73%, 60% and 37%, respectively. 2.5 Finally, preliminary investigations demonstrate the utility of palladium-catalysed enolate arylation in the synthesis of β-carbolines.

APA, Harvard, Vancouver, ISO, and other styles

50

Sheth, Ritesh B. "Development of new synthetic methodologies and the synthesis of natural products." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 101 p, 2010. http://proquest.umi.com/pqdweb?did=1993336351&sid=2&Fmt=2&clientId=8331&RQT=309&VName=PQD.

Full text

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!