Dissertations / Theses: 'Alkaloid synthesis; Indole alkaloids'

1

Callaghan, Owen. "Synthetic and mechanistic studies in free radical." Thesis, University of Strathclyde, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366957.

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2

Hollinshead, S. P. "Enantiospecific approaches to indole alkaloids." Thesis, University of York, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379030.

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3

Swain, D. J. "Stereoselective synthesis of indole alkaloids." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238115.

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4

Wingfield, M. "A novel approach to the total synthesis of corynanthe indole alkaloids via cyclopentanoid intermediaries." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374789.

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5

McLay, Neil Robert. "The synthesis of bridged indole alkaloids." Thesis, University of York, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280410.

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6

Hilton, Stephen. "Towards the synthesis of indole alkaloids." Thesis, Kingston University, 2002. http://eprints.kingston.ac.uk/20698/.

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Radical chemistry and, in particular, tandem radical chemistry has rarely been used in the synthesis of the 'Strychnos' and 'Aspidosperma' alkaloids. These two classes of compounds are structurally complex, possess a range of biological activity and present a synthetic challenge. Previous routes to these molecules are reviewed in the first section . of this thesis. The utility of radical chemistry, tandem radical chemistry and 1,S'I hydrogen atom abstraction towards the syntheses of complex molecules is outlined with examples that demonstrate the potential of radical chemistry. A new synthetic approach towards the spiropyrrolidinyl oxindole alkaloids is presented, which utilises tandem radical chemistry. The radical sequence involves an initial 1,5- hydrogen atom abstraction, followed by a Sew-trig cyclisation onto the indole C-3 position. This is governed by the directing effect of a cyano group at the C-2 position of indole. The tricyclic core of the oxindole alkaloids can be readily obtained following an oxidative decyanation. In the course of these studies a novel product was observed during the cyclisation of the N-isopropyl precursor. Modification of the cyclisation precursor to incorporate the N-pentenyl group resulted in the formation of the tetraeyelic core of the Strychnos and Aspidosperma alkaloids. This arose from a subsequent 6-exo¬trig cyclisation after formation of the tricyclic core. Cyclisation of the N-pentynyl radical precursor led to the expected cyclised product along with an unexpected pentaeyelic structure, which arose from an unprecedented further l,S-hydrogen atom abstraction followed by a 4-exo-dig cyclisation. The second approach involves the addition of alkyl radicals onto the indole C-3 position to generate the tricyclic core of the spiropyrrolidinyl oxindole alkaloids. This approach is directed towards a total synthesis of the oxindole alkaloids, horsfiline and coerulescine. However, this approach led instead to rearrangement before cyclisation followed by intramolecular transfer of the cyano group from the indole C-2 to C-3 position. A novel approach to the formation of 3-substituted 2-cyanoindoles is also presented which negates the need for protection of the indole nitrogen allowing for a flexible approach to the tandem radical cyclisation precursors. The experimental conditions for the synthesis of all new compounds prepared during this work along with characterisation data are presented.

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Ouali, Dehimi. "Enantioselective synthesis of novel corynanthe indole alkaloid synthons." Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315329.

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8

Cheung, Man-ki. "Synthesis of inverto-yuehchukene and substituted 1,2,3,4-tetrahydrocyclopent[b]indole /." [Hong Kong] : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B14786898.

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9

張文驥 and Man-ki Cheung. "Synthesis of inverto-yuehchukene and substituted 1,2,3,4-tetrahydrocyclopent[b]indole." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31234148.

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10

Ferreira, Jasmin. "Asymmetric Total Synthesis of the Pentacyclic Indole Alkaloid (+)-Tacamonine." Master's thesis, Faculty of Science, 2019. http://hdl.handle.net/11427/31346.

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(+)-Tacamonine, a natural product isolated from the Central African plant Tabernaemontana eglandulosa, belongs to the relatively new tacaman class of pentacyclic monoterpenoid indole alkaloids. Its close structural similarity to the potent cerebral vasodilator (-)-vincamone has promoted several efforts towards its synthesis, culminating in the appearance of two asymmetric and seven racemic syntheses in the literature. This dissertation details the successful execution of our strategy for the concise, highly-efficient, asymmetric total synthesis of (+)-tacamonine. Chapter 1 serves as an introduction to the tacaman class, including the proposed biosynthesis for members of this class, followed by a review of the reported synthetic approaches to tacamonine. Chapter 2 details the evolution of our approach based on the use of key radical cyclization methodology to ultimately accomplish a total synthesis of the target. An investigation of the diastereoselectivity displayed in the radical cyclization step is also described through computational methods. Our route followed a novel ABC to ABCD to ABCDE ring-construction strategy, which first involved the synthesis of 3,4-dihydro--carboline as well as a chiral acid ester fragment that was acquired through Evans’ auxiliary-controlled alkylation chemistry. The latter set the absolute configuration at C-20 bearing the ethyl group in the D-ring, and thereafter, the two fragments were coupled together before being advanced to the radical cyclization precursor. Radical cyclization then led to the formation of the desired cis D/Ering junction in a diastereomeric ratio of 10:1, the major diastereomer displaying the required C-3/C-14 to C-20 anti-diastereoselectivity. Subsequent global reduction and oxidation/E-ring formation processes afforded the target in 8 steps over 10 operations in 25% overall yield and in 96% enantiomeric excess. X-Ray crystallographic structure determination provided conclusive evidence for the formation of the target.

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李輝途 and Victor Lee. "Synthetic study of seco-yuehchukene and inverto-yuehchukene." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1987. http://hub.hku.hk/bib/B31208241.

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12

黃子達 and Tze-tat Edward Wong. "A general synthetic route to Yuehchukene analogues via 7alpha-methoxycarbonyl-9-methyl-6-oxo-5,6,6abeta,7betaB,8,10aB-hexahydroindeno [2,1-b] indole, and related studies on 1-methoxyindole." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1992. http://hub.hku.hk/bib/B31232851.

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13

Barbey, Sabine. "A novel approach to the ergot alkaloid skeleton." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294855.

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Allard, James Edward. "Novel approaches to the asymmetric synthesis of indole alkaloids." Thesis, Loughborough University, 2004. https://dspace.lboro.ac.uk/2134/33613.

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The tetracyclic system (219) shares the same heterocyclic skeleton as a plethora of highly bioactive indole alkaloids, exemplified by ajmalicine (161) and deplancheine (204). [Illustration omitted.] Building on earlier work from our research group we recognised that a suitably substituted bicyclic lactam (266) could act as a precursor in an intramolecular N-acyliminium mediated cyclisation leading to targets such as (219). [Illustration omitted.] Methodology has been developed to remove the chiral auxiliary group. Manipulation of the template (219) has allowed us to achieve a novel total synthesis of deplancheine (208) and provided valuable insight for a future asymmetric synthesis of (204).

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15

Parker, Ashley Stuart. "Photochemical approaches to the synthesis of the indole alkaloid ibogamine." Thesis, University of Bristol, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427907.

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16

Zehr, Peter S. "Synthesis of novel alkaloids using squaric acid esters." Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4411.

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Thesis (Ph. D.)--West Virginia University, 2005. Title from document title page. Document formatted into pages; contains xvii, 207 p. : ill. Includes abstract. Includes bibliographical references (p. 97-101).

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17

Dawood, Dawood Hosni. "Towards the synthesis of monoterpenoids indole alkaloids of the aspidospermatan and strychnan type." Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14155/document.

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L'objectif de ce travail était d'accéder au squelette des alcaloïdes de type Aspidosperma et Strychnos à partir d'arylcyclohexa-2,5-diènes. Ces derniers sont d'abord synthétisés par réaction de Birch alkylante, puis ont été désymétrisés dans un premier temps par des réactions de Michael. Cette réaction fournit la cétone de Büchi, le noyau tétracyclique des alcaloïdes Aspidosperma en seulement en 6 étapes et un rendement global de 17%. Dans un second temps, la réaction d'amination oxydante catalysée par des métaux (Pd, Cu) a été développée. Cette réaction a permis un accès rapide au squelette pentacyclique d’aza-aspidospermanes et au squelette tétracycliques des alcaloïdes de type Strychnos. En parallèle, nous avons décrit une approche vers le squelette pentacyclique de la mossambine et la strychnine The aim of this work was to access the skeleton of the Aspidosperma and the Strychnos alkaloids using arylcyclohexa-2,5-dienes as common synthetic precursors. Initially, these arylcyclohexadienes were synthesized through Birch reductive alkylation reactions. The desymmetrization of these cyclohexadienes was developed via the Michael addition reaction, providing the Büchi ketone, the tetracyclic core of Aspidosperma alkaloids, in only 6 steps and 17% overall yield. On the other hand, we described the oxidative amination reaction catalyzed by metals (Pd, Cu). The palladium oxidative amination reaction allowed a fast access to the pentacyclic framework of aza-aspidospermanes and the tetracyclic framework of the strychnos. In parallel, we have described an approach toward the pentacyclic skeleton of mossambine and strychnine

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18

Stempel, Erik [Verfasser]. "Construction of cyclohepta[b]indoles in the total synthesis of indole alkaloids / Erik Stempel." Hannover : Technische Informationsbibliothek (TIB), 2017. http://d-nb.info/1137165995/34.

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19

Lam, Shuk-mei, and 林淑媚. "Studies on diazoketone rearrangements and application toward the synthesis of welwistatin." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/196009.

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20

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

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

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21

Matsuoka, Junpei. "Total Synthesis of Indole Alkaloids Based on Direct Construction of Pyrrolocarbazaole Scaffolds via Gold-Catalyzed Cascade Cyclizations." Doctoral thesis, Kyoto University, 2020. http://hdl.handle.net/2433/253241.

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京都大学 0048 新制・課程博士 博士(薬学) 甲第22405号 薬博第843号 新制||薬||241(附属図書館) 京都大学大学院薬学研究科薬学専攻 (主査)教授大野浩章, 教授高須清誠, 教授竹本佳司 学位規則第4条第1項該当 Doctor of Pharmaceutical Sciences Kyoto University DFAM

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22

Thomas, Christopher Ian. "Application of N-acyliminium ions in the asymmetric synthesis of indole alkaloids." Thesis, Loughborough University, 2004. https://dspace.lboro.ac.uk/2134/34996.

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We have developed a new and highly stereoselective approach to indolizino[8,7-b]indole derivatives such as (A) and indolizino[2,3-a]quinolizidines (B). Our protocol involves the cyclisation of pendent aromatic substituents onto N-acyliminium intermediates as a key ring-forming step. The indolizino[2,3-a]quinolizidines are of great interest and significance since this heterocyclic template is found within a plethora of indole alkaloids. [Illustration omitted.] In order to demonstrate the synthetic potential of this methodology we have established conditions for removal of the pendent hydroxymethyl substituent from cyclisation products such as (A) and (B). Furthermore, we have demonstrated the functionalisation of our cyclisation products via conjugate addition chemistry. We have utilised this methodology and herein describe the asymmetric synthesis of both enantiomers of deplancheine (C), furnishing the natural product and its enantiomer with >95% e.e. Our route relies on a highly stereoselective cyclisation reaction to access the indolizino[2,3-a]quinolizidine template from a readily available non-racemic chiral template.

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23

黃偉雄 and Wai-hung Wong. "Synthetic studies of N-benzenesulphonyl-6-oxo-5,6,8,9,10,10a-hexahydroindeno [2,1-b]indole and related compounds as intermediatesof C-7 substituted Yuehchukene analogues." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1990. http://hub.hku.hk/bib/B31210077.

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陳國邦 and Kwok-pong Chan. "A synthetic approach to Yuehchukene analogues via alpha beta-unsaturated-2-acylindoles." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1990. http://hub.hku.hk/bib/B31209117.

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25

曹國安 and Guo-an Cao. "Study of Diels-Alder reactions in the syntheses of Yuehchukene analogues and optically active Yuehchukene." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1993. http://hub.hku.hk/bib/B31232942.

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26

Wilkie, Ross Philip. "New methods for the diastereoselective construction of vicinal quaternary stereocenters and their application to the total synthesis of the bioactive (±)-dehalo-perophoramidine." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/8265.

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This thesis describes a novel total synthesis of (±)-dehalo-perophoramidine (a dehalogenated analogue of the natural product perophoramidine). The key synthetic transformation involves the construction of vicinal quaternary stereocenters which were installed diastereoselectively. A Claisen rearrangement was used to install the first quaternary stereocenter then a Corey-Chaykovsky-type reaction and a Hosomi-Sakurai-type reaction were used to install the second quaternary stereocenter. Investigations directed towards the total synthesis of the communesin family of natural products are also described. In Chapter 1, the natural products perophoramidine and the communesins are introduced and their related biosynthesis is discussed. The isolation, architectural motifs and biological properties of the natural products are described and discussed. Previously reported approaches to perophoramidine and the communesins are reviewed focussing on how the vicinal quaternary stereocenters are formed in each case. Chapter 1 concludes with the retrosynthetic plan used to form dehalo-perophoramidine. In Chapter 2, previous research from the Westwood group is reviewed focusing on an asymmetric Claisen rearrangement which could potentially be used to install a quaternary stereocenter asymmetrically. A previously reported novel Cope rearrangement, potentially useful for a communesin synthesis, is optimised using microwave, neat and high-temperature flow conditions and leads to the synthesis of an intermediate containing two allyl substituents. In Chapter 3, attempts to functionalise selectively the two allyl substituents are described which was eventually achieved by a regioselective iodoetherification reaction. This leads to the synthesis of two relatively advanced intermediates for a communesin synthesis. Although the total synthesis of the communesins was not achieved, a proposed route from the advanced intermediates to the natural products is described. In Chapter 4, a novel method to construct vicinal quaternary stereocenters is disclosed using a Corey- Chaykovsky-type reaction and a Hosomi-Sakurai-type reaction. A regioselective iodolactonisation, analogous to that presented in Chapter 3, is used to functionalise selectively two allyl substituents that culminates in the preparation of a pentacyclic lactam. In Chapter 5, the total synthesis of (±)-dehalo-perophoramidine is completed and its structure is confirmed by a NMR doping experiment with an authentic sample. The biological activity of dehalo- perophoramidine is investigated and compared to that of perophoramidine. Chapter 5 culminates in an attempted synthesis of the natural product perophoramidine using the route that was used to make dehalo-perophoramidine.

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Khera, Jagjit Singh. "Stereoselective synthesis of indole alkaloids via the application of N-acyliminium ion chemistry." Thesis, Loughborough University, 2006. https://dspace.lboro.ac.uk/2134/35968.

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Members of the indole family of alkaloids have long been the subject of scientific investigation. This interest has been stimulated not only by the structural diversity of this family of alkaloids but also because the physiological and biological properties of some are legendary. Our group has developed a facile and highly stereoselective approach to the important indolizino[5,7-b]indole (A) and indolizino[2,3-a]quinolizidine (B) templates from readily available non-racemic substrates. The key ring-forming step involves the cyc1isation of a pendent indole substituent onto an N-acyliminium intermediate. The potential for application of our novel methodology in target synthesis has been demonstrated by removal of the hydroxymethyl moiety from indolizino[5,7-b]indole and indolizino[2,3-a]quinolizidine derivatives. We have demonstrated the functionalisation of the indolizino[2,3-a]quinolizidine derivatives via conjugate addition chemistry, forming derivatives such as (C), which may be converted to more complex indole alkaloids such as hirsutine (0). We have also utilised our methodology in the asymmetric synthesis of (+)-12b-epidevinylantirhine (E).

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28

George, Rosemary. "Synthesis and conformational studies of indolizines." Thesis, Rhodes University, 1994. http://hdl.handle.net/10962/d1005032.

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The present investigation has involved a kinetic and mechanistic study of the thermal cyclization of 3-acetoxy-3-(2-pyridyl)-2-methylenepropanoate esters and related compounds to 2-substituted indolizines. Substrates for the kinetic study were prepared via the Baylis-Hillmann reaction of pyridine-2-carboxaldehydes with acrylate esters, acrylonitrile and methyl vinyl ketone. The resulting hydroxy compounds were then acetylated to afford the acetoxy derivatives, thermal cyclization of which gave the corresponding 2-substituted indolizines. The cyclization reactions was followed using 'H NMR spectroscopy and were shown to follow firstorder kinetics. The influence of the various substituents on the observed first-order rate constants has been examined and variable temperature studies have permitted evaluation of activation parameters for the formation of methyl indolizine-2-carboxylate and ethyl indolizine-2-carboxylate. An alternative route to 2-substituted indolizines via halogenated derivatives was explored and several halogenated 2-pyridyl derivatives were synthesised and their thermal cyclization to indolizines was attempted. Novel 5-methylindolizine-2-carboxamides were prepared as part of this investigation and dynamic NMR spectroscopy was used to study internal rotation about the amide N-CO bond in these compounds.

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29

Voûte, Nicholas. "Rearrangements in the indolo[2,3-b]quinoline system : a novel approach to the synthesis of perophoramidine and the communesins /." Thesis, St Andrews, 2008. http://hdl.handle.net/10023/486.

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30

Beard, Mark. "Cis-selectivity in the Pictet-Spengler reaction and studies towards the synthesis of indole alkaloids." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/cisselectivity-in-the-pictetspengler-reaction-and-studies-towards-the-synthesis-of-indole-alkaloids(84087b18-14bf-4121-aa51-61b24254e4ca).html.

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Previous work in our group as been directed towards the synthesis of (+)-ajmaline, a biologically important indole alkaloid. Its total synthesis was completed in the 1990s. An important early step in its total synthesis from D-tryptophan is the trans-selective Pictet-Spengler reaction. However, in our hands, we are able to force cis-selectivity in the reaction which allows us to begin our work towards its synthesis from the cheaper L-tryptophan. The group's previous progress had reached a key ring cyclisation step; however it was discovered that this step was sensitive to the type of protecting group on the Nb-nitrogen. The benzyl protecting group, which was originally in place, was found to position the electrophilic aldehyde group too far away from the nucleophile for the reaction to take place. Therefore, the previous work was re-investigated and the purposely-chosen pivaloyl Nb-protecting group was employed early in the new synthesis. The synthesis was progressed to the afore-mentioned cyclisation step whilst improving some of the individual steps. The conditions that allow for the observed cis-selectivity in the Pictet-Spengler reaction have only recently been developed. Further investigations now reveal that the temperature and the nature of the C(3) and C(5) substituents have a direct effect on the observed selectivity. Cis-specificity is generally achieved when the reaction is conducted at low temperature and both substituents contain a potential π-stacking group. However, it is still unclear whether it is the interaction of the potential π-stacking groups that is responsible for cis-specificity in this reaction.

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31

Gritsch, Philipp [Verfasser]. "Towards a synthesis of (-)-actinophyllic acid : applying the divinylcyclopropane rearrangement to the synthesis of indole alkaloids / Philipp Gritsch." Hannover : Technische Informationsbibliothek (TIB), 2015. http://d-nb.info/108423887X/34.

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32

Johnston, Craig A. "Progress towards the synthesis of perophoramidine : formation of the contiguous quaternary centres." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3546.

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Perophoramidine 1 is a halogenated natural product which contains two contiguous quaternary centres within its structure. In this thesis, approaches towards the synthesis of perophoramidine are described. In particular, the synthesis of the tetracyclic core structure and the formation of the quaternary centres have been examined. In Chapter 1, the natural product perophoramidine 1 is introduced and its isolation, structure and biological activity is discussed. The structurally related communesin family of natural products are also introduced before the literature published on both the biosynthesis and laboratory synthesis of perophoramidine 1, is reviewed. Finally the Westwood group's approach towards the synthesis of perophoramidine 1 is introduced with a summary of non-halogenated model system investigations previously carried out within the group being provided. Chapter 2 describes studies towards the synthesis of an appropriately halogenated indolo[2,3-b]quinoline core structure of perophoramidine 1. This then allowed methodology previously developed within the group on model system substrates to be applied to the formation of the first of the two quaternary centres required for the synthesis of perophoramidine 1. Chapter 3 describes the attempted formation of the second quaternary centre using an ester alkylation approach. After initial studies failed to generate the desired quaternary centre, non-halogenated model system studies were carried out in an attempt to develop an alternative approach. In Chapter 4, model system studies were continued with cyclic ether compounds investigated as potential intermediates towards the synthesis of perophoramidine 1. The results obtained in this chapter provided a novel route to the formation of the second quaternary centre and led to a redesigned approach towards perophoramidine 1 being developed. In Chapter 5, this redesigned approach was applied to the halogenated intermediates synthesised in Chapter 1. This led to the formation of the first halogenated intermediate synthesised within the group which contained the two contiguous quaternary centres required for the synthesis of perophoramidine 1.

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33

Clauss, Rainer. "Radical cyclisation studies of chiral α-acylamino radicals : a model study towards Tacaman indole alkaloid synthesis". Master's thesis, University of Cape Town, 1996. http://hdl.handle.net/11427/16138.

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Includes bibliographical references. he radical cyclisation of chiral 4,5-substituted N-acyl-2-aza-6-heptenyl radicals, derived from D-ribose, has been undertaken as a model stuay towards Tacaman indole alkaloid synthesis. The radical cyclisations were conducted using tributyltin hydride/AIBN in refluxing benzene. The α-acylamino radicals added to double bonds which were activated by an ethoxycarbonyl substituent. No reduction of the radicals by the tributyltin hydride was observed. Those radicals incorporating an isopropylidene ketal at the 4 and 5 positions as chiral auxiliary showed excellent regio- and stereoselectivity. Out of a possible 4 diastereomers, only two were obtained in a 2:8 ratio. It was established that the isopropylidene ketal directed the cyclisation stereoselectively and that no stereoselectivity was observed in the absence of the chiral auxiliary.

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34

Lebar, Matthew D. "Antarctic Tunicates and Endophytic Fungi: Chemical Investigation and Synthesis." Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3638.

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Drug discovery is reliant on new developments in natural product chemistry as well as advances in chemical synthesis. The interconnectivity and interdependence of natural and synthetic investigation in drug discovery is evident. The chemical exploration reported herein elaborates the relationship between natural product chemistry and chemical synthesis. Of particular interest are chemicals from organisms residing in less accessible environments, particularly Antarctica and endophytic microbial communities. Degradation via reductive ozonolysis of palmerolide A, a macrocyclic polyketide isolated from the Antarctic tunicate Synoicum adareanum, and subsequent synthetic preparation of the resulting polyols (1,2,6-hexanetriol and 1,2,3,6-hexanetetraol) led to a revision in the absolute configuration of the bioactive natural product (7R, 10R, 11R to 7S, 10S, 11S). A partial synthesis of palmerolide A (C3-14) was completed using Grubb’s 2nd generation catalyst to couple fragments formed using the previously developed methodology from the degradation study. Isolation of indole-pyrimidine containing alkaloids meridianins A, B, C, and E from the Antarctic tunicate Synoicum sp. prompted a synthetic investigation of psammopemmin A, a related alkaloid from the Antarctic sponge Psammopemma sp. resulting in reassignment of the structure of psammopemmin A to that of meridianin A. Both meridianin A and psammopemmin A were synthesized through a Suzuki coupling of the same 4-indolol nucleophile to the apposite pyrimidine electrophile. Several synthetic 3-pyrimidylindole analogs were also prepared and investigated for central nervous system, antimalarial, and cytotoxic activity. Chemical investigation of extracts from mangrove fungal endophytes that displayed antimalarial properties in vitro resulted in the isolation of several potent but cytotoxic and cytostatic compounds: cytochalasin D, roridin E, and 12,13-deoxyroridin E.

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35

Cera, Gianpiero <1985&gt. "Au(I) Catalyzed Manipulation of Propargylic Alcohols: A New Route Towards the Synthesis of Indole Alkaloids." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6417/.

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In this work we presented several aspects regarding the possibility to use readily available propargylic alcohols as acyclic precursors to develop new stereoselective [Au(I)]-catalyzed cascade reactions for the synthesis of highly complex indole architectures. The use of indole-based propargylic alcohols of type 1 in a stereoselective [Au(I)]-catalyzed hydroindolynation/immiun trapping reactive sequence opened access to a new class of tetracyclic indolines, dihydropyranylindolines A and furoindolines B. An enantioselective protocol was futher explored in order to synthesize this molecules with high yields and ee. The suitability of propargylic alcohols in [Au(I)]-catalyzed cascade reactions was deeply investigated by developing cascade reactions in which was possible not only to synthesize the indole core but also to achieve a second functionalization. Aniline based propargylic alcohols 2 were found to be modular acyclic precursors for the synthesis of [1,2-a] azepinoindoles C. In describing this reactivity we additionally reported experimental evidences for an unprecedented NHCAu(I)-vinyl specie which in a chemoselective fashion, led to the annulation step, synthesizing the N1-C2-connected seven membered ring. The chemical flexibility of propargylic alcohols was further explored by changing the nature of the chemical surrounding with different preinstalled N-alkyl moiety in propargylic alcohols of type 3. Particularly, in the case of a primary alcohol, [Au(I)] catalysis was found to be prominent in the synthesis of a new class of [4,3-a]-oxazinoindoles D while the use of an allylic alcohol led to the first example of [Au(I)] catalyzed synthesis and enantioselective functionalization of this class of molecules (D*). With this work we established propargylic alcohols as excellent acyclic precursor to developed new [Au(I)]-catalyzed cascade reaction and providing new catalytic synthetic tools for the stereoselective synthesis of complex indole/indoline architectures. In questo lavoro di tesi abbiamo presentato diversi aspetti riguardanti la possibilità di utilizzare alcoli propargilici come precursori aciclici nello sviluppo di nuove reazioni a cascata stereoselettive [Au(I)] catalizzate per la sintesi di architetture indoliche altamente funzionalizzate. Alcoli propargilici su base indolica di tipo 1, sono stati utilizzati per sviluppare un processo a cascata per la sintesi di una nuova classe di indoline tetra cicliche, diidropiranilindoline A e furoindoline B. Un protocollo enantioselettivo è stato successivamente studiato per la sintesi di tali strutture con buone rese ed elevati eccessi enantiomerici. Diversi alcoli propargilici sono stati studiati nello sviluppare reazioni a cascata [Au(I)] catalizzate per la sintesi e funzionalizzazione di anelli indolici. Precursori su base anilinica di tipo 2, si sono rivelati essere precursori di eccellenza per la sintesi di [1,2-a]-azepino-indoli di tipo C. Nel descrivere quest’ultima reattività abbiamo riportato evidenze sperimentali di una nuova specie [Au(I)]-carbenica in grado di dirigere la chiusura dell’anello a sette termini in maniera altamente chemoselettiva. La flessibilità chimica degli alcoli propargilici è stata infine studiata cambiata la natura dell’intorno chimico con differenti gruppi N-alchilati in precursori di tipo 3. Utilizzando come catena un alcol primario, la selettività della reazione si è dimostrata completamente rivolta verso la sintesi della classe dei [4,3-a]-ossazino-indoli D, mentre utilizzando alcoli allilici abbiamo riportato il primo esempio di sintesi e funzionalizzazione enantioselettiva [Au(I)]catalizzata, di questa classe di molecole (D*). Concludendo, in questo lavoro abbiamo stabilito gli alcoli propargilici, essere precursori d’eccezione in reazioni a cascata Au(I) catalizzate riportando nuovi strumenti sintetici per la sintesi stereo selettiva di architetture indoliche ed indoliniche estremamente complesse.

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36

Bode, Moira Leanne. "Synthetic and spectroscopic studies of indolizine derivatives." Thesis, Rhodes University, 1994. http://hdl.handle.net/10962/d1005050.

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The crystalline compound resulting from thermal cyclization of the Baylis-Hillman product, methyl 3-hydroxy-2-methylene-3-(2-pyridyl)propanoate, has been identified as the indolizine derivative, methyl indolizine-2-carboxylate, and this approach involving the reaction of pyridine-2-carboxaldehydes and acrylate analogues has been established as a general route to 2-substituted indolizines. The ease of cyclization the Baylis-Hillman products to indolizines has been shown to increase by converting the hydroxy group to an acetoxy group, and a range of acetylated Baylis-Hillman products were prepared and cyc1ized to the corresponding 2-substituted indolizines, generally in good overall yield. In the reaction of pyridine-2-carboxaldehyde and methyl vinyl ketone, the intermediate cyclized readily and directly to the corresponding indolizine. One- and two-dimensional ¹H and ¹³C NMR analysis of the 2-substituted indolizine products has permitted complete assignment of all ¹H and ¹³C NMR signals, as well as the measurement of all coupling constants for these compounds. A kinetic and mechanistic study has been conducted on the Baylis-Hillman reaction using ¹H NMR spectroscopy. A range of substrates has been examined and the reaction has been found to be third-order overall. A mechanism involving an addition - elimination sequence is proposed, which fits the kinetic data and accounts for observed substituent effects. Reaction of N,N-dimethylacrylamide with pyridine-2-carboxaldehyde in the presence of the tertiary amine catalyst, DABCO, in chloroform, yielded an unexpected product which has been identified by single crystal X-ray diffraction analysis as 1-(2,2,2-trichloro-1-hydroxyethyl)pyridine. Attempted extension of the general indolizine route to the preparation of chromene systems by reacting salicylaldehyde with methyl acrylate in the presence of DABCO, also led to an unexpected, crystalline material, identified by single crystal X-ray diffraction analysis as the coumarin derivative, 3-[(2-formylphenoxy)methyl]coumarin.A series of chloroquine analogues have been prepared from indolizine-2-carboxylic acid, pyrrolo[I,2-a]quinoline-2-carboxylic acid and imidazo[I,2-a]pyridine-2-carboxylic acid by reaction with suitable amines in the presence of the coupling reagent 1, I' -carbonyldiimidazole. This route has been shown to be a vast improvement on earlier procedures and has provided access to both secondary and tertiary indolizine-2-carboxamides. A range of N,N-dialkylindolizine-2-carboxamides have been prepared by this route, and the influence of substituents on their N-CO rotational energy barriers has been determined using variable temperature ¹H and ¹³C NMR techniques. Intercalation with natural DNA by both chloroquine and the synthesized chloroquine analogues has been examined using UV spectrophotometry, and ¹H and ³¹P NMR spectroscopy. The pyrrolo[I,2-a]quinolines have been shown to be DNA intercalators with binding affinities similar to that of the known antimalarial intercalator, chloroquine. In a preliminary study the synthesis of a short oligonucleotide has been undertaken and changes have been observed in the ¹H and ³¹P NMR spectra of the oligonucleotide on addition of the intercalator, chloroquine.

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37

Marsch, Nils [Verfasser]. "Studies towards the synthesis of raputindole A, a dimeric indole alkaloid from the rutaceous tree Raputia simulans / Nils Marsch." München : Verlag Dr. Hut, 2015. http://d-nb.info/1076437370/34.

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38

Jarret, Maxime. "Synthèses totales d’alcaloïdes indolo-monoterpéniques : (–)-17-nor-excelsinidine, (+)-16-épi-pléiocarpamine, (+)-16-hydroxyméthyl-pléiocarpamine et (+)-taberdivarine H." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS527.

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La pléiocarpamine est un alcaloïde indolo-monoterpénique de la famille des mavacurans. L’intérêt de cette substance naturelle réside dans sa capacité d’assemblage avec divers alcaloïdes indoliques donnant lieu à des bisindoles de structures complexes possédant des activités biologiques significatives. Plusieurs stratégies ont été étudiées pour la synthèse totale de ce composé pentacyclique. Notamment, la contraction d’un cétolactame a été envisagée pour la formation du cycle E. De manière inattendue, cette stratégie a conduit à la première synthèse totale de la (–)-17-nor-excelsinisine, un alcaloïde zwitterionique avec des activités antivirales. En parallèle, cette substance naturelle a été obtenue par cyclisation oxydante bioinspirée entre le formylester et l’atome d’azote aliphatique de la geissoschizine. La quaternarisation de ce dernier a ensuite permis de guider la chimiosélectivité de cette réaction vers le noyau indolique. Ainsi le couplage oxydant avec l’atome d’azote indolique a généré la liaison signature des mavacurans. Grâce à cette stratégie, plusieurs alcaloïdes de cette famille : (+)-taberdivarine H, (+)-16-hydroxyméthyl-pléiocarpamine et (+)-16-épi-pléiocarpamine, ont été synthétisés. Par la suite, une synthèse totale racémique de cette dernière a également été réalisée en seulement neuf étapes grâce à l’addition 1,4 intermoléculaire diastéréosélective d’un iodure de vinyle sur un indolylacrylate tétracyclique et à la fermeture finale du cycle D par substitution nucléophile. Le développement d’une version énantiosélective a été initié. Finalement, une étude a été réalisée pour la synthèse de la pycnanthinine, un bisindole dérivé de la pléiocarpamine Pleiocarpamine is a monoterpene indole alkaloid of the mavacuran family. The main interest of this natural product is its ability to assemble with various indole alkaloids to give structurally complex bisindoles with significant biological activities. Several strategies have been studied for the total synthesis of this pentacyclic compound. Especially, the ring contraction of a ketolactam was contemplated for E-ring formation. Unexpectedly, this strategy led to the first total synthesis of (–)-17-nor-excelsinisine, a zwitterionic alkaloid with antiviral activities. Simultaneously, this natural product was obtained via a bioinspired oxidative cyclization between the formylester and the aliphatic nitrogen atom of geissoschizine. Quaternarization of the latter allowed to guide the reaction chemoselectivity towards the indole nucleus. Therefore the oxidative coupling with the indolic nitrogen atom etablished the signature bond of the mavacurans. Thanks to this strategy, several alkaloids of this family: (+)-taberdivarine H, (+)-16-hydroxymethyl-pleiocarpamine and (+)-16-epi-pleiocarpamine, were synthetized. Subsequently, a racemic total synthesis of the latter was completed in only nine steps via a diastereoselective intermolecular 1,4 addition of a vinyl iodide into a tetracyclic indolylacrylate and a final D-ring closure by nucleophilic substitution. The development of an enantioselective version has been initiated. Finally, a study was performed for the assembly of pycnanthinine, a pleiocarpamine-derived bisindole

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39

Reyes, Loya David. "Etude synthétique de la koumine, réactions domino régiosélectives vers des lactones indoliques et synthèse totale de la (+/-)-goniomithine." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMR119.

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Une étude synthétique de la koumine par une stratégie basée sur une étape de désymétrisation a permis de développer, par un résultat inattendu, une fragmentation de 1,3-cyclohexanediones en lactones. Suite à ce résultat, une étude méthodologique a été réalisée en partant de différentes dicétones substituées pour synthétiser des lactones indoliques, ainsi que déterminer la régiosélectivité et la diastéréosélectivité. Finalement, la synthèse totale de la goniomitine a été éffectuée en utilisant cette méthode de fragmentation A synthetic study of koumine by a strategy based on a desymmetrization step led, through an unexpected result, to the development of a fragmentation of 1,3-cyclohexanediones into lactones. Following this result, a methodological study was carried out starting from different substituted diketones to synthesize indolic lactones, as well as to determine regioselectivity and diastereoselectivity. Finally, the total synthesis of goniomitine was performed using this fragmentation method

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40

Wu, Tao. "Synthetic studies on polycyclic indole alkaloids." [Ames, Iowa : Iowa State University], 2006.

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41

Ross, Frances I. "Efficient synthetic routes to indole alkaloids." Thesis, Heriot-Watt University, 1999. http://hdl.handle.net/10399/588.

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42

Cochrane, Philip. "Short synthetic routes to indole alkaloids." Thesis, Heriot-Watt University, 2000. http://hdl.handle.net/10399/529.

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43

Fray, Edward Brian. "Synthetic approaches towards novel indole alkaloids." Thesis, Loughborough University, 1994. https://dspace.lboro.ac.uk/2134/33280.

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This thesis describes several synthetic approaches to some novel indole alkaloids. The Introduction (Chapter One) outlines the need for continuous discovery of new antibiotics in todays environment. The family of Kinamycin antibiotics is described along with their biosynthesis and the evidence of the novel biosynthetic precursor known as Pre-Kinamycin. Chapter Two (2.1) deals with a retrosynthetic analysis leading to a study of Tandem Directed Ortho-Metallation reactions and a proposed synthesis of Pre-Kinamycin. Section 2.2 describes the study of stable analogues of indole-2,3-quinodimethane and the Dials–Alder reactions thereof. Also Dials-Alder reactions of pyrano[3,4-b]indol-3-ones with benzyne and the subsequent manipulation of the carbazole-based products are detailed. Section 2.3 outlines the study of the Friedel–Crafts acylation reaction with respect to the indole nucleus and the application of such a reaction to the synthesis of the Pre-Kinamycin skeleton. Investigations into acid mediated cyclisations to form quinones and the use of Weinreb amides as acylating agents are also described. Chapter Three (3.1) examines the problems of iron overload diseases (haemochromatosis) and the efforts to produce effective iron chelators. Section 3.2 describes the discovery of four novel indole alkaloids known as Uvarindoles and their possible consideration as iron chelators. Section 3.3 examines two retrosynthetic analyses towards Uvarindole B and the investigation into the synthesis thereof, involving similar methodology as that developed in section 2.3. Chapter Four describes the relevant experimental details for the intermediates described in sections 2.1 through 3.3 and the respective spectroscopic data obtained. Chapter Five gives the references for all the relevant work quoted in above sections.

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44

Rutherford, M. J. "Dimeric indole and quinolinone alkaloids." Thesis, University of Ulster, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378774.

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45

Jonsson, Ann-Louise. "Synthetic studies of marine indole alkaloids and related systems /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-587-9/.

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46

Adla, Santosh Kumar [Verfasser], and Thomas [Akademischer Betreuer] Lindel. "Prenyl Rearrangements on Indole Alkaloids from the Marine Bryozoan Flustra foliacea: Synthesis of Flustramine A and Studies Towards ent-Flustramine C and Debromoflustramine E / Santosh Kumar Adla ; Betreuer: Thomas Lindel." Braunschweig : Technische Universität Braunschweig, 2013. http://d-nb.info/1175822388/34.

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47

Mauger-Chalaye, Hélène. "Réactions des nitrones avec les noyaux indoliques : nouvelles approches synthétiques d'alcaloïdes indoliques bio-actifs." Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE10047.

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Parmi les composes naturels possedant des proprietes antivirales et/ou antitumorales, les alcaloides indoliques font l'objet d'un interet particulier. Afin de former le motif (3-indolyl)methylamine, base structurale de certains de ces derives bio-actifs, nous avons etudie la reactivite des nitrones vis-a-vis des noyaux indoliques. Utilisant 2 modes differents d'activation des nitrones, nous avons pu acceder a deux classes de produits : les n-hydroxylamines indoliques, et les 3,3-diindolylalcanes. Chacune des deux methodologies mises au point a par la suite ete exploitee pour synthetiser d'une part des derives bis-indoliques naturels ou non symetriques, d'autre part des 1,2-diamines indoliques. Ces dernieres sont des precurseurs potentiels des topsentines, des nortopsentines et du discodermindole, composes bio-actifs isoles d'eponges marines et possedant un noyau imidazole ou imidazoline. Nous avons envisage de former ces cycles azotes en condensant les 1,2-diamines obtenues avec un acide indolique convenablement active. Dans le cadre de ce projet, nous avons verifie la faisabilite chimique des strategies envisagees en utilisant le 1,2-diaminoethane comme modele. Un analogue debrome et protege du discodermindole a egalement ete obtenu.

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Callis, David John. "Synthetic studies towards the indole alkaloid, aspidospermidine." Thesis, University of Sussex, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340832.

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Lee, V. J. "Synthetic study of seco-yuehchukene and inverto-yuehchukene /." [Hong Kong : University of Hong Kong], 1987. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12366961.

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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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Dissertations / Theses on the topic 'Alkaloid synthesis; Indole alkaloids'

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