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Published: 4 June 2021
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1

Coates, Helen Margaret. "Synthetic studies towards stemofoline synthesis." Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238730.

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2

Swenson, Helen Rachel. "Studies in synthetic peptides and heterocyclic synthesis." Thesis, University of Edinburgh, 1999. http://hdl.handle.net/1842/13061.

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The following work documents three studies undertaken using solid phase synthesis techniques. Interaction of the zinc metalloprotease, endothelin converting enzyme-1(ECE-1), with its peptidic natural substrate big endothelum-1 has been investigated via an SAR study, using solid phase peptide synthesis (SPPS). Truncated forms of the substrate had been previously reported to inhibit ECE-1, this was confirmed however the big ET-1 analogues were shown to be substrates for the enzyme. A short study of the substrate specificity of ECE-1 was carried out. The synthesis of vast libraries of peptides using combinational synthesis has been used to accelerate the drug discovery process. Purification of these mixtures has not been previously attempted. 17-Tetrabenzo [a,c,g,i]fluoroeneyhethoxycarbonyl (Tbfmcc) developed for use with single peptides of proteins, has been used to achieve facile purification of five peptide libraries synthesised using SP. The methodology was fully optimised for the efficient separation of the desired library members from all impurities by exploiting the affinity of TBfmoc for carbon. A potential small molecule inhibitor of the zinc metalloenzyme, farnesyl transferase (FTase), was designed. The efficient solution phase synthesis of this novel structure is reported its adaptation to solid phase synthesis is described, with the view to using multiple parallel synthesis techniques to synthesise a range of analogous.
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3

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.

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4

Xiang, Alan X. "Total synthesis of clerocidin and related studies ; Synthetic studies toward borrelidin /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2000. http://wwwlib.umi.com/cr/ucsd/fullcit?p9981971.

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5

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.

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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.
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6

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.

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7

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.

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8

Viseux, Eddy Michel Elie. "Synthetic studies towards a total synthesis of roseophilin." Thesis, University of Sussex, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420509.

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9

Charles, Mark David. "Synthetic studies toward a total synthesis of morphine." Thesis, University of Sussex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272077.

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10

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.

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11

Chen, Yong. "Synthetic Studies on Total Synthesis of Azaspiracid-3." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1385895424.

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12

Poon, Ch-yan. "Synthetic studies towards isaindigotidione." Click to view the E-thesis via HKUTO, 2004. http://sunzi.lib.hku.hk/hkuto/record/B31200709.

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13

Mitchell, Anthony Stewart, and mikewood@deakin edu au. "Synthetic studies towards anthraquinones." Deakin University. School of Biological and Chemical Sciences, 1994. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20051017.151445.

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The oxidation of substituted phenols with phenyliodonium diacetate in methanol was found to afford 2,4-cyclohexadienones, 2,5-cyclohexadienones or mixtures of isomers depending on the substrate being oxidized. A reaction mechanism was proposed for this oxidation which involved an intermediate aryloxenium ion. A strong correlation was observed between the experimentally determined product ratios and the results predicted by calculation of the LUMO coefficients of the proposed intermediates, Annulation of these cyclohexadienones with the anion derived from cyanophthalide afforded substituted anthraquinones in high yields. The chemistry relating to the annulation of Michael acceptors with phthalide anions was comprehensively reviewed. A mild selective method for the oxidation of hydroquinones to quinones using dibenzoyl peroxide and base is presented. A general synthetic approach to C-glycosylanthraquinones was presented, based on the annulation of a C-glycosylcyclohexadienone with the anion derived from cyanophthalide, A suitable precursor to a C-glycosylcyclohexadienone, 2-(2’,3’,4’,6’-tetra-0-acetyl-|3-D-glucopyranosyl)benzyloxybenzene, was prepared via the reaction of benzoylbromoglucose with 2-benzyloxyphenylmagnesium bromide, A group of molecules were prepared by a Marschalk reaction between /ewcoquinizarin and aldehydo-sugsrs. These compounds are potential bioreductive alkylating agents in which molecular simplicity can be achieved without overly sacrificing DNA binding ability.
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14

Ryan, Glen Richard. "Synthetic studies with diterpenoids." Thesis, University of Auckland, 1988. http://hdl.handle.net/2292/1991.

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Chapter one of this thesis reports an investigation of the synthesis of potential amber odorants from abietic acid. The acid catalysed rearrangement of abietic acid afforded two isomeric dienes the structures of which have been elucidated. Compounds containing the diene functionality were found to be unstable. However, removal of the diene system afforded stable compounds which are suited to further synthetic modification. Although the skeletal features possessed by a class of amber odorants were successfully introduced stereochemical control proved difficult. The stereochemistry of two intermediates was unambiguosly assigned by single-crystal X-ray diffraction experiments. The second chapter describes the successful conversion of totarol into conjugated dienolides possessing the B/C-ring present in type A and type C nagilactones. Consequently totarol may be considered as a useful model for the preparation of the biologically active nagilactones. In the course of this work several unusual rearrangements were observed. The products of rearrangement were characterised by 2-D n.m.r. and single crystal X-ray diffraction experiments and reaction mechanisms are proposed. The third chapter of this thesis reports the synthesis of the amber odorant, γ-bicyclohomofarnesal, from podocarpic acid. Analogues in which C-19 is functionalised were also prepared. However these compounds were odorless.
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15

Lane, Charlotte Alice Louise. "Synthetic studies towards taxol." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267854.

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16

Howard, P. N. "Synthetic studies on sinefungin." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376917.

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17

Grainger, Caroline R. "Synthetic Studies Towards Tuberostemospironine." Thesis, University of Bristol, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520267.

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18

Poon, Ch-yan, and 潘綽欣. "Synthetic studies towards isaindigotidione." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31028020.

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(Uncorrected OCR) Abstract of thesis entitled SYNTHETIC STUDIES TOWARDS ISAINDIGOTIDIONE Submitted by Poon Ch Yan for the degree of Doctor of Philosophy at The University of Hong Kong in October 2004 Banlangen (WlWMi), more commonly known in the West as baphicacanthus, is a well-reputed traditional Chinese medicinal herbal drug commonly used to treat ailments such as influenza. It was even prescribed recently in Hong Kong for bolstering immunity against the Severe Acute Respiratory Syndrome (SARS) virus. It is the root of Isatis indigotica Fort. (Cruciferae), a biennial plant found along the valley of the Yangtze River (Changjiang) in central China. Isaindigotidione (I) is an alkaloid isolated from the root of I. indigotica. The organic extracts of this root were found to be active in antiendotoxic tests, indicating that isaindigotidione, like other alkaloids from the root, may possess interesting biological activity. As isaindigotidione is found naturally only in small quantities in I. indigotica, further investigation will only be possible when sufficient quantities are synthesized. Chemically, the structure of isaindigotidione is a novel derivative of indolizino[7,6- cjquinoline (II) found in natural and synthetic products for the first time. To our knowledge, no synthetic studies of this compound or its derivatives have yet been reported, and this thesis describes our efforts to synthesize isaindigotidione and its analogues. The main building blocks of the tetracyclic framework II were L-proline (V) and isatin (VI). The acylation of L-proline derivative VII by BOC-protected isatin was achieved under basic conditions to give phenylglyoxylic amide VIII. It was found that, in the presence of base under reflux, VIII underwent bis-cyclization to afford II. It was noted that four transformations (aldol cyclization, dehydration, acylation, and BOC-deprotection) occurred in a one-pot operation very efficiently to produce excellent yields of II. The isaindigotidione analogues III and IV were also synthesized by the same strategy. Substituents at C-7 were introduced by cuprate addition and a Heck reaction to intermediate IX. Epimerization at the C-7 centre was found to occur under the bis-cyclization conditions, and analogues III and IV were obtained as epimeric mixtures. Unfortunately, it was discovered upon extensive investigation that these organometallic conjugate addition reactions did not lend themselves to the addition of the 2,6-dimethoxy-l-phenol moiety to IX and its derivatives, which this retroanalysis indicates is required for the synthesis of isaindigotidione. Several factors were found to deter the addition of the desired substituent, including the steric demands of IX, and the low reactivity of phenyl and aryl organometallic reagents. O. ^N�''/ i H ^O OMe OH OMe II ,NL !""'H ^CH3 i H ^O III IV COOH "N H O^N H VI H .0 OMe OMe � ^ BOC f OMe VII VIII IX
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Chemistry
Doctoral
Doctor of Philosophy
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19

Cowell, Justin Kimborough. "Synthetic studies towards asteriscanolide." Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361721.

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20

Bainbridge, Jeremy D. E. "Synthetic studies towards gelsemine." Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389255.

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21

Rescourio, Gwenaëlla. "Synthetic studies towards (+)-lactacystin." Thesis, University of Nottingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404148.

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22

Dube, Henry. "Synthetic studies toward myxothiazoles." Thesis, University of Nottingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410420.

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23

Ryan, A. P. "Synthetic studies on chalaurenol." Thesis, University of Nottingham, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356038.

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24

Fraser, Rebecca Jane. "Synthetic studies towards gelsemine." Thesis, University of Nottingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403697.

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25

Roberts, D. L. "Synthetic studies towards forskolin." Thesis, University of Nottingham, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376185.

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26

Astley, Martin Peter. "Synthetic studies towards furanocembranes." Thesis, University of Nottingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358036.

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27

Smith, Graham F. "Synthetic studies towards funiculosin." Thesis, University of Nottingham, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277800.

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28

Brookfield, Frederick Arthur. "Synthetic studies towards pateamine." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311760.

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29

Hobbs-Mallyon, David. "Synthetic studies on tricyclospirodienones." Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315042.

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30

Dunn, Sara F. C. "Synthetic studies on sulphonyloxiranes." Thesis, University of Newcastle Upon Tyne, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239143.

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31

Roe, Michael B. "Synthetic studies towards solenolides." Thesis, University of Salford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238837.

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32

Sharpe, Andrew. "Synthetic studies towards aspidospermidine." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260583.

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33

Angell, Richard Martyn. "Synthetic studies towards histrionicotoxin." Thesis, University of Reading, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317634.

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34

Watkins, Alison Jane. "Synthetic studies towards herbimycin." Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292423.

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35

Webster, N. M. H. "Synthetic studies towards pinguisone." Thesis, University of Southampton, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373205.

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36

Reed, Mark Andrew. "Synthetic studies towards histrionicotoxin." Thesis, University of Sussex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310265.

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37

Fletcher, Matthew James Edwin. "Synthetic studies towards (-)-Dysiherbaine." Thesis, University of Bristol, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268523.

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38

Richardson, Stewart K. "Synthetic studies towards virantmycin." Thesis, Sheffield Hallam University, 1985. http://shura.shu.ac.uk/20276/.

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The use of vinylphosphonium salts in the construction of acyclic and cyclic systems by both ourselves and others is reviewed. The alkylthio and arylthio vinylphosphonium salts are used in an unsuccessful approach to the synthesis of the tetrahydroquinoline natural product virantmycin. The use of this approach in the early stages of a synthesis of carbaprostacyclin and analogues is also examined. The synthesis of virantmycin was also investigated using a regioselective Dieckmann reaction. Two procedures have been developed for the synthesis of the mixed 0,S-diester required to study the cyclisation. The first of these has as the key step a one carbon homologation reaction of a benzaldehyde to a phenylacetic acid derivative. The second relies on a pericyclic rearrangement reaction. The latter route has proved more successful and the Dieckmann product has been made using this procedure. Applications of this to the synthesis of virantmycin are discussed. The use of methyl methylsulphinylmethyl sulphide in the one carbon homologation for the synthesis of the Dieckmann precursor has been extended. Thus a set of conditions has been developed for the synthesis of chloroketenedithioacetals from ketenedithioacetal S-oxides which complements the only other known set of conditions for this transformation. Under our conditions the ketene dithioacetal S-oxide derived from 2-aminobenzaldehyde cyclises to give two indoles. A modified set of conditions are presented which give rise to anomalous products. In the light of this a mechanism is proposed. Finally the use of this strategy is extended to a synthesis of benzofurans and further discussion shows how this might be used in a general preparation of thiol esters and in the synthesis of other heterocyclic systems or natural products.
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39

Wong, Leon Sui-Man. "Synthetic studies towards (+)-himbacine." Thesis, The University of Sydney, 2003. https://hdl.handle.net/2123/27895.

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Himbacine 1 is a naturally occurring alkaloid isolated from the bark of Galbulimima, a species of magnolia. Himbacine exhibits high selectivity for presynaptic receptors and is a promising lead compound against Alzheimer’s disease. A novel, highly modular strategy for the total synthesis of himbacine has been devised. An investigation into this approach has led to the preparation of new analogues of himbacine. The key step of this synthesis involves an intramolecular Diels—Alder reaction of a pentadienyl acrylate. This reaction was modeled with four related precursors 60, 62, 111 and 112. The stereochemical outcome of each reaction was accurately measured. These experimental results compare favourably with transition structure populations predicted using B3LYP/6—31+G(d) theory. The parent system 60 cyclises with moderate endo selectivity; the presence of either a C5-methy1 substituent or a C3- bromine atom results in a slight shift towards the trans-fused exo stereoisomer. The presence of both C3-Br and C5-CH3 substituents results in a marked improvement in stereoselectivity for exo—cycloadducts. Interpretation of the computed transition structures allows insights into the influences affecting the outcome of each reaction. A variation of this intramolecular Diels—Alder reaction has been applied to the synthesis of 4,4a-didehydro himbacine analogues. The outcome of the intramolecular Diels—Alder reaction for this cyclohexenyl—appended substrate closely resembles the model system, suggesting that the same stereocontrolling influences are at play. Other key C-C bond forming steps include a regioselective Suzuki—Miyaura coupling, and a Stille coupling reaction to unite the vinylstannane to give 4,4adidehydrohimbacine 116 and 4,4a-didehydro-N-methylhimandravine 192. This general approach forms the basis of synthetic efforts towards himbacine. The 4,4a—didehydro analogues are not easily transformed into their corresponding 4,4asaturated natural products due to the requirement for an overall trans-reduction of this double bond. To achieve this conversion, placement of a carbonyl group adjacent to the C4a position was planned, which would allow epimerisation at C4a to the required stereochernistry. 6-Ex0-trz'g acyl radical cyclisations onto conjugated dienes and enynes were examined, with the latter providing a more promising approach to himbacine. Progress towards the total synthesis of himbacine Via this IMDA/radical cyclisation approach currently stands at Boc-protected 5-oxo-1',2'-didehydrohimbacine. The required absolute configurations at all eight stereocentres have been secured. Functional group interconversions should complete the total synthesis.
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40

Naik, R. H. "Synthetic studies in terpenes." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 1985. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/3225.

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41

Tejwani, R. B. "Synthetic studies in biotin." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 1992. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/3018.

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42

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.

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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.
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43

Crawford, Claire Frances. "Synthetic studies towards a total synthesis of hemibrevetoxin B." Thesis, University of Leeds, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435783.

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44

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.

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45

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

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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.
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46

Turner, S. P. D. "Synthetic studies on Faktor I." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354691.

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47

Haym, Isabell. "Synthetic studies towards berkelic acid." Thesis, University of Auckland, 2012. http://hdl.handle.net/2292/19583.

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This thesis is concerned with the development of novel synthetic routes towards the highly substituted tetracyclic core of berkelic acid, a novel bioactive natural compound isolated from an extremophile found in Berkeley Pit Lake. This highly acidic (pH = 2.5-2.7), metal laden lake, formed through infiltration of an abandoned copper mine in Montana, USA, is the source of the Penicillium sp. Pitna 4 from which berkelic acid was isolated in 2006. Bioassays on berkelic acid have shown selective activity against OVCAR-3, an ovarian cancer cell line, as well as inhibitory activity towards the matrix metalloproteinase MMP-3 and the cysteine protease caspase-1. Due to its bioactivity and the complex structure, berkelic acid represents an interesting target for synthetic chemists. This study describes two approaches towards the tetracyclic core of berkelic acid. The first approach is concerned with the synthesis of the benzannulated spiroacetal moiety using a styrene derivative for a Kulinkovich reaction to form a cyclopropanol. Further studies of the selective ring opening of the cyclopropanol and acidic spiroacetalisation afforded the tricyclic benzannulated spiroacetal moiety of berkelic acid. To further examine the scope of the synthetic strategy, a series of analogous benzannulated spiroacetals were synthesised using the established approach. A second approach describes extensive studies on the synthesis of the tricyclic isochromane core of berkelic acid employing an oxa-variant of the Hofmann-Lo��ffler-Freytag reaction to construct the isochromane ring. Use of Au(I)-catalysed hydroarylation to establish the precursor for the key Hofmann-Lo��ffler-Freytag reaction and Pd-catalysed carbonylation to introduce the carboxylic acid completed the novel synthetic approach towards this tricyclic moiety. To demonstrate the scope of the developed strategy, the synthesis of the tetracyclic spiroacetal core was next achieved, making use of a second oxidative radical cyclisation step to introduce the spiroacetal moiety.
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48

Wilson, Zoe Elizabeth. "Synthetic studies towards berkelic acid." Thesis, University of Auckland, 2010. http://hdl.handle.net/2292/6086.

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This thesis describes the synthetic endeavours towards berkelic acid, an extremophile derived bioactive natural product. Penicillium sp. Pitna 4 is a fungus isolated from Berkeley Pit Lake, a metal laden, pH 2.5 lake which formed when an abandoned copper mine in Butte, Montana filled with infiltrating ground water. Berkelic acid is one of several bioactive natural products isolated from this unlikely source and has been found to have desirable selective activity against the ovarian cancer cell line OVCAR-3, as well as inhibitory activity against caspase-1 and matrix metalloprotease-3. Synthetic access to this molecule is highly desirable due to its bioactivity and novel tetracyclic structure as well as the fact that the planned bioremediation of Berkeley Pit Lake may eliminate its natural source. The synthetic studies undertaken have focused on developing a flexible strategy for the synthesis of berkelic acid that allows for future modification to structure to allow investigation of biological activity. The strategy is based on the use of a novel one-pot Horner-Wadsworth-Emmons/oxa-Michael cascade to couple two advanced intermediates ��� a phosphonate and a lactol. A final deprotection/spiroketalisation step then furnishes the spiroketal moiety. Careful functional group manipulations and key introduction of chirality were pivotal in the successful synthesis of a series of coupling partners which allowed the successful synthesis of a series of tricyclic analogues of berkelic acid as well as the entire tetracyclic core, with and without full substitution on the aromatic ring. The formal total synthesis of berkelic acid faltered at the penultimate step, but this project has none the less established a sound approach to this molecule which will build the foundations for a future total synthesis.
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49

Almutairi, Tahani. "Synthetic studies towards multichromophore arrays." Thesis, University of East Anglia, 2015. https://ueaeprints.uea.ac.uk/59255/.

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The overall aim of this project was to investigate strategies for linking macrocyclic chromophores to form arrays. Firstly the aim was to link a porphyrin to a triphenylene through phenyl alkynes. Interestingly, this study discovered a mesogenic dibromtetramethoxy triphenylene – the least heavily substituted triphenylene liquid crystal reported to date. The results of this investigation, however, show that, in general, it was challenging to force the reaction between porphyrin and triphenylene components to form acetylene links. Dimerization of the acetylene components was observed as the predominant reaction in all cases. However, it was possible to isolate a porphyrin-triphenylene dyad structure. The second aim of this study was to investigate the synthesis of novel chromophore dyads and triads 102, 104 and 134 which are based on porphyrin and tetrabenzotriazaporphyrin (TBTAP) components. The first aim was to synthesise porphyrin–phenyl-TBTAP 102. A precursor porphyrin bearing aminoisoindoline functionality was successfully prepared. However, it could not be converted to either the porphyrin–phenyl-TBTAP 102 dyad or porphyrin-azaBODIPY-porphyrin triad 134. On the other hand, the suggested strategy towards the synthesis of porphyrin-TBTAP dyads linked through flexible chains (104) remains promising. Magnesium TBTAB-OH 135 was synthesised as one important reactant. However, the unfortunate choice of bromododecyloxyporphyrin 141, meant the synthesis of the desired dyad could not be achieved within this project because it could not be separated from excess dibromododecane. However, simple modification of the strategy (e.g using bromododecanol) will allow the compounds to be prepared in the future.
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50

Lai, Michelle Yu Huay. "Synthetic Studies Towards the Crisamicins." Thesis, University of Auckland, 2002. http://hdl.handle.net/2292/2393.

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This thesis describes synthetic work directed towards the synthesis of the dimeric pyranonaphthoquinone antibiotic crisamicin A 1.46 and its regioisomer 2.77. The synthetic strategy adopted is based on a double furofuran annulation/oxidative rearrangement strategy that has been successfully used by this research group to prepare a related dimeric pyranonaphthoquinone based on the actinorhodin skeleton. The retrosynthesis that was adopted (see Scheme 1.47, page 59) required the initial preparation of a key bis-naphthoquinone 1.267 which in turn is available from bisnaphthalene 1.268 that bears acetyl groups at C-7 and C-7’. Initial work concentrated on the construction of the biaryl linkage of bis-7- acetylnaphthalene 1.268 using a palladium(0)-mediated Suzuki-Miyaura homocoupling of the key triflate 1.269 (prepared in 10 steps from vanillin 1.271) using bis(pinacolato)diboron 1.179. This coupling method successfully afforded binaphthyls 2.8b and 2.8d which were subjected to attempts to effect either double bromination, double acetylation or double Fries rearrangement to a more functionalised biaryl system. Disappointingly, none of these methods allowed introduction of the key acetyl group at C-7 and C-7’ onto the initial biaryls 2.8b and 2.8d. Attention then turned to the synthesis of the bis-7-acetylnaphthalene 1,268 that was required for the ensuing furofuran annulation reaction starting from triflate 2.7 that already contained an acetyl group at C-7, then effecting formation of the key biaryl linkage. Attempts to prepare 7-acetyltriflate 2.7 via either Fries rearrangement of acetates 2.33a or 2.9a, or via bromination of acetate 2.33a, naphthol 2.56 or benzyl ether 2.6 were unsuccessful. An alternative approach for the preparation of 7-acetyltriflate 2.7 involved the preparation of 2-acetylcarbamate 2.74 from carbamate 2.64 via a directed ortho-metalation, followed by reaction of the derived ortho-lithiated species with N-methoxy-N-methylacetamide 2.71. However, this strategy resulted only in low yields of the desired 2-acetylcarbamate 2.74, although initial model work did provide methodology for the successful conversion of carbamate 2.68 to 2-acetyl-l-naphthol 2.73. The synthetic target of this thesis shifted to the regioisomer of crisamicin A 2.77 when attempts to introduce an acetyl group atC-7 of triflate 2.9 failed. However formation of the 6-acetyltriflate 2.81b was successful from triflate 2.9b. A subsequent one-pot in situ Suzuki-Miyaura homocoupling of triflate 2.81b with boronate 2.89 furnished dimmer 2.76b. Oxidation of dimer 2.76b to bis-naphthoquinone 2.80 was then accomplished using silver(II) oxide and 6 M nitric acid. With the key bis-6-acetylnaphthoquinone 2.80 in hand, an efficient double furofuran annulation reaction was carried out using 2-trimethylsilyloxyfuran 1.88 affording the desired bis-furonaphthofuran adduct 2.79 as an inseparable l:l mixture of diastereomers 2.79a and 2.79b. However, initial experiments to effect the double oxidative rearrangement of bis-furonaphthofuran adducts 2.79 using either silver(Il) oxide and 6 M nitric acid or with ceric ammonium nitrate in aqueous acetonitrile to the bisfuronaphthopyran 2.7 8 were unsuccessful. Attention then turned to the preparation of bis-furonaphthopyran 2.78 from the 6-acetyltriflate 2.81b via initial oxidation of triflate 2.81b to naphthoquinone 3.3 followed by furofuran annulation and then oxidative rearrangement. Attempts to effect the key Suzuki-Miyaura homocoupling of furonaphthofuran 3.2 to bis-furonaphthofuran 2.79, or of furonaphthopyran 3.1 to bis-furonaphthopyran 2.78, using catalyst PdCl2(dppf) and ligand dppf were unsuccessful. The work achieved herein constitutes the synthesis of an advanced intermediate for the synthesis of the crisamicin analogue 2.79. The final synthesis of the regioisomer of crisamicin A 2.77 can be completed by preparing bis-furonaphthopyran bis-lactol 2.78 using more powerful palladium(0) catalysts and ligands for the Suzuki-Miyaura homocoupling of the monomeric furonaphthopyran 3.1. Subsequent reduction af 2.78 using triethylsilane and trifluoroacetic acid will then afford the bis-cyclic ether 3.15, which can undergo deprotection of the methyl ether and epimerisation at C-5 upon treatment with excess boron tribromide to finally furnish the regioisomer of crisamicin A 2.77. An investigation into the double oxidative rearangement of bis-furonaphthofuran 2.79 to the bis-lactol 2.78 could also be carried out by the use of several alternative oxidising agents, such as phenyliodine(III) bis(trifluoroacetate) (PIFA), phenyliodine(III) diacetate (PIDA), polymer-supported (diacetoxyiodo)benzene (PSDIB), Fremy's salt, iron trichloride or CrO3.
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