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Synthèse totale des amphidinolides C et U
No full textThe general objective of my thesis work was to achieve the synthesis of amphidinolides C2 and U, marine macrolactones isolated from a dinoflagellate, Amphidinium sp.. This document has been divided into three main parts: the bibliography part consisting of three chapters, the presentation of my project and finally, the 3rd part results and discussion developed over two chapters. A concise description of these molecules was made in the first chapter: amphidinolides C2 and U are 25- and 20-membered macrolactones respectively. The amphidinolide C family is composed of C, C2 and C3 and studies of their cytotoxicity on KB and L1210 cells have shown that amphidinolide C is the most active against these cancer lines. Then in chapters 2 and 3, the studies reported in the literature on the synthesis of the different fragments of these molecules have been described. This enabled us to identify 14 research groups that have worked on synthetic approaches. Among them, only Carters' groups (amphidinolides F and C), Fürstner's group (amphidinolides C and F) and our laboratory (amphidinolide F) were able to complete the total synthesis of certain molecules of this family. The results obtained during my thesis were presented in this last part over two chapters. Our convergent synthesis approach of the different C1-3 amphidinolides is based on the total synthesis of three target chains (C1-C9, C10-C17, C18-C34). With the C1-C9 and C10-C17 fragments in hand, we were able to access the C18-C34 synthon of the C amphidinolides, corresponding exactly to the C13-C29 fragment of the U amphidinolides. Subsequently, the coupling of these synthons made it possible to carry out for the first time the total synthesis of amphidinolide C2. In the literature, no approach had provided access to this compound. The strategy for the total synthesis of amphidinolide U that we wanted to carry out was based on a coupling reaction between the sp2 and sp3 carbons originating from the C5 and C6 positions. The C6-C12 fragment had to be obtained from (S)-glycidol. The C1-C5 synthon could be synthesized from 3-bromobut-3-en-1-ol or 3-methylbut-3-en-1-ol. For the formation of the C5-C6 bond, all attempts according to the Negishi process ended in failure. The Suzuki-Miyaura coupling, on the other hand, allowed us to perform the C5-C6 type bond on a model. After optimization, the process was applied to our fragments, with the creation of the C5-C6 bond, corresponding to the first synthesis of the C1-C12 fragment of the amphidinolides U. My work has constituted a major advance for the total synthesis of these target molecules.L'objectif général de mon travail de thèse a été de réaliser la synthèse des amphidinolides C2 et U, des macrolactones marines isolées d'un dinoflagellé, Amphidinium sp.. Ce document a été divisé en trois grandes parties : la partie bibliographie constituée de trois chapitres, la présentation de mon projet et enfin, la 3è partie résultats et discussion développée sur deux chapitres. Une description concise de ces molécules a été réalisée dans le premier chapitre : les amphidinolides C2 et U sont des macrolactones à 25 et 20 chaînons respectivement. La famille de l'amphidinolide C est composée de C, C2 et C3 et les études de leur cytotoxicité sur les cellules KB et L1210 ont montré que l'amphidinolide C est le plus actif contre ces lignées cancéreuses. Ensuite dans les chapitres 2 et 3, les études rapportées dans la littérature sur la synthèse des différents fragments de ces molécules ont été décrites. Ceci nous a permis de recenser 14 groupes de recherche qui ont travaillé sur des approches synthétiques. Parmi eux seuls les groupes de Carters (amphidinolides F et C), le groupe de Fürstner (amphidinolides C et F) et notre laboratoire (amphidinolide F) ont pu achever la synthèse totale de certaines molécules de cette famille. Les résultats obtenus, durant ma thèse, ont été présentés dans la dernière partie sur deux chapitres. Notre approche de synthèse convergente des différents amphidinolides C1-3, est basée, sur la synthèse totale de trois chainons cibles (C1-C9, C10-C17, C18-C34). Les fragments C1-C9 et C10-C17 en main, nous avons pu accéder au synthon C18-C34 des amphidinolides C correspondant exactement au fragment C13-C29 de l'amphidinolide U. Par la suite, le couplage de ces synthons a permis de réaliser pour la première fois la synthèse totale de l'amphidinolide C2. Dans la littérature aucune approche n'avait permis d'accéder à ce composé. La stratégie de synthèse totale de l'amphidinolide U que nous souhaitions mener, quant à elle, était basée sur une réaction de couplage entre les carbones sp2 et sp3 issus des positions C5 et C6. Le fragment C6-C12 devait être obtenu à partir du (S)-glycidol. Le synthon C1-C5 pouvait être synthétisé à partir du 3-bromobut-3-èn-1-ol ou du 3-méthylbut-3-èn-1-ol. Pour la formation de la liaison C5-C6, toutes les tentatives selon le processus de Negishi se sont soldées par des échecs. Le couplage de Suzuki-Miyaura nous a permis en revanche de réaliser la liaison de type C5-C6 sur un modèle. Après optimisation, le processus a été appliqué à nos fragments, avec la création de la liaison C5-C6, correspondant à la première synthèse du fragment C1-C12 de l'amphidinolides U. Mes travaux ont constitué une avancée majeure pour la synthèse totale de ces molécules cibles
Les Seereer du Nord-Ouest (Sénégal) Face à La Traite Négrière
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Total synthesis of amphidinolides C and U
No full textL'objectif général de mon travail de thèse a été de réaliser la synthèse des amphidinolides C2 et U, des macrolactones marines isolées d'un dinoflagellé, Amphidinium sp.. Ce document a été divisé en trois grandes parties : la partie bibliographie constituée de trois chapitres, la présentation de mon projet et enfin, la 3è partie résultats et discussion développée sur deux chapitres. Une description concise de ces molécules a été réalisée dans le premier chapitre : les amphidinolides C2 et U sont des macrolactones à 25 et 20 chaînons respectivement. La famille de l'amphidinolide C est composée de C, C2 et C3 et les études de leur cytotoxicité sur les cellules KB et L1210 ont montré que l'amphidinolide C est le plus actif contre ces lignées cancéreuses. Ensuite dans les chapitres 2 et 3, les études rapportées dans la littérature sur la synthèse des différents fragments de ces molécules ont été décrites. Ceci nous a permis de recenser 14 groupes de recherche qui ont travaillé sur des approches synthétiques. Parmi eux seuls les groupes de Carters (amphidinolides F et C), le groupe de Fürstner (amphidinolides C et F) et notre laboratoire (amphidinolide F) ont pu achever la synthèse totale de certaines molécules de cette famille. Les résultats obtenus, durant ma thèse, ont été présentés dans la dernière partie sur deux chapitres. Notre approche de synthèse convergente des différents amphidinolides C1-3, est basée, sur la synthèse totale de trois chainons cibles (C1-C9, C10-C17, C18-C34). Les fragments C1-C9 et C10-C17 en main, nous avons pu accéder au synthon C18-C34 des amphidinolides C correspondant exactement au fragment C13-C29 de l'amphidinolide U. Par la suite, le couplage de ces synthons a permis de réaliser pour la première fois la synthèse totale de l'amphidinolide C2. Dans la littérature aucune approche n'avait permis d'accéder à ce composé. La stratégie de synthèse totale de l'amphidinolide U que nous souhaitions mener, quant à elle, était basée sur une réaction de couplage entre les carbones sp2 et sp3 issus des positions C5 et C6. Le fragment C6-C12 devait être obtenu à partir du (S)-glycidol. Le synthon C1-C5 pouvait être synthétisé à partir du 3-bromobut-3-èn-1-ol ou du 3-méthylbut-3-èn-1-ol. Pour la formation de la liaison C5-C6, toutes les tentatives selon le processus de Negishi se sont soldées par des échecs. Le couplage de Suzuki-Miyaura nous a permis en revanche de réaliser la liaison de type C5-C6 sur un modèle. Après optimisation, le processus a été appliqué à nos fragments, avec la création de la liaison C5-C6, correspondant à la première synthèse du fragment C1-C12 de l'amphidinolides U. Mes travaux ont constitué une avancée majeure pour la synthèse totale de ces molécules cibles.The general objective of my thesis work was to achieve the synthesis of amphidinolides C2 and U, marine macrolactones isolated from a dinoflagellate, Amphidinium sp.. This document has been divided into three main parts: the bibliography part consisting of three chapters, the presentation of my project and finally, the 3rd part results and discussion developed over two chapters. A concise description of these molecules was made in the first chapter: amphidinolides C2 and U are 25- and 20-membered macrolactones respectively. The amphidinolide C family is composed of C, C2 and C3 and studies of their cytotoxicity on KB and L1210 cells have shown that amphidinolide C is the most active against these cancer lines. Then in chapters 2 and 3, the studies reported in the literature on the synthesis of the different fragments of these molecules have been described. This enabled us to identify 14 research groups that have worked on synthetic approaches. Among them, only Carters' groups (amphidinolides F and C), Fürstner's group (amphidinolides C and F) and our laboratory (amphidinolide F) were able to complete the total synthesis of certain molecules of this family. The results obtained during my thesis were presented in this last part over two chapters. Our convergent synthesis approach of the different C1-3 amphidinolides is based on the total synthesis of three target chains (C1-C9, C10-C17, C18-C34). With the C1-C9 and C10-C17 fragments in hand, we were able to access the C18-C34 synthon of the C amphidinolides, corresponding exactly to the C13-C29 fragment of the U amphidinolides. Subsequently, the coupling of these synthons made it possible to carry out for the first time the total synthesis of amphidinolide C2. In the literature, no approach had provided access to this compound. The strategy for the total synthesis of amphidinolide U that we wanted to carry out was based on a coupling reaction between the sp2 and sp3 carbons originating from the C5 and C6 positions. The C6-C12 fragment had to be obtained from (S)-glycidol. The C1-C5 synthon could be synthesized from 3-bromobut-3-en-1-ol or 3-methylbut-3-en-1-ol. For the formation of the C5-C6 bond, all attempts according to the Negishi process ended in failure. The Suzuki-Miyaura coupling, on the other hand, allowed us to perform the C5-C6 type bond on a model. After optimization, the process was applied to our fragments, with the creation of the C5-C6 bond, corresponding to the first synthesis of the C1-C12 fragment of the amphidinolides U. My work has constituted a major advance for the total synthesis of these target molecules
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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