1,720,953 research outputs found
不斉ヘテロ ディールス・アルダー反応に用いる新規有機分子触媒複合系の開発
Get PDF室蘭工業大学Muroran Institute of Technology博士（工学）application/pdf医薬品をはじめとする多くの生物活性化合物は光学活性物質であり, その鏡像異性体は薬と毒のような，互いに異なる生体内作用を示すことが多い。そのため，有効な一方の鏡像異性体を高立体選択的に合成するための不斉合成反応の開発，特に不斉触媒を用いる触媒的不斉合成反応の開発は，新薬やキラル機能性分子を創製するために重要である。その不斉触媒の中で，金属を含有しない有機分子触媒は毒性が無く，空気中で安定であり取り扱いやすく安価であるなどの利点を有するため, 次世代の環境調和型触媒として現在活発な研究開発が行なわれている. 光学活性スピロインダノール類は，抗がん，抗 HIVや抗マラリヤ活性などの多彩な生物活性を示すことから，現在そのスピロインダノール骨格を構築するための有機合成反応の開発が活発に行われている。著者は，その合成反応として触媒的不斉ヘテロ ディールス・アルダー反応に着目し，その反応に有効な有機分子触媒複合系を開発することを目的として本研究を行った。著者は，有機分子触媒複合系として，β—アミノアルコールおよびβ—アミノシリルエーテルをそれぞれ触媒とし，アミノ酸を助触媒とするイサチン類とエノン類との不斉ヘテロ ディールス・アルダー反応を検討した。その結果，触媒としてはその分子中に第１級アミノ基や第１級水酸基，またシロキシ基をもつシンプルなキラルβ—アミノアルコールまたおよびβ—アミノシリルエーテルが，また助触媒としてはアミノ基に保護基したα—アミノ酸が本反応中で複合的に触媒活性機能を発現し，優れた化学収率とジアステレオ選択性およびエナンチオ選択性で目的のキラルイサチン誘導体が得られることが明らかとなった。本研究において著者は，光学活性スピロインダノール類の合成に有効な不斉ヘテロ ディールス・アルダー反応に用いる新規有機分子触媒複合系を開発することに成功した。開発した本触媒系は，他の創薬のために有用な不斉触媒反応においても触媒機能を示すことが期待され，さらに，本反応によって得られる光学活性スピロインダノール類は抗がん作用や他の様々な生物活性化合物の合成中間体としても有用であることから，本研究の成果は, 新薬創製を指向した合成開発研究に大きく貢献できると期待される.Many biologically active compounds, including pharmaceuticals, are optically active and often only one of the enantiomer shows a high biologically activity. Therefore, it is important to develop the synthetic methodology for providing only necessary enantiomer. As the methodology, catalytic asymmetric synthesis, in which the use of a low amount of a chiral catalyst theoretically enables infinite production of optically active compounds, is the most efficient in the synthetic organic chemistry field. Moreover, this methodology is also important in terms of energy saving and environmental friendliness. The chiral catalysts used in catalytic asymmetric syntheses can be divided into two categories of organometallic catalyst and metal-free organocatalyst. Particularly, organocatalyst is stable in air, nontoxic, easy to handle, and inexpensive, so they are being focused on as next-generation, environmentally friendly catalysts. Spirooxindoles are considered to be promising scaffolds in drug discovery. The structure of spirooxindoles is contained in many compounds having pharmacological activities such as contraceptive, anti-HIV, anticancer, antituberculosis, antimalarial, and antiproliferative drugs. Therefore, the development of an effective strategy for the preparation of highly optically pure spirooxindoles is a significantly challenging task in research. The hetero Diels–Alder (HDA) reaction is a versatile tool for effectively forming heterocyclic compounds. Especially, the catalytic asymmetric version of this reaction is the most efficient and convenient method for constructing a chiral heterocyclic skeleton, which acts as a precursor for many biologically active compounds and drugs. In this class of HDA reactions, the reaction of isatins with enones is one of the superior organic transformations for providing unique chiral spirooxindoles containing quaternary chiral carbon center on the structure. Author tried to explore new catalysts component system for this reaction using isatins as diene and enones as dienophile. As a result, author developed simple two catalysts component system consisting of primary β-amino alcohol or γ-amino silyl ether as catalysts and N-protected amino acid as a co-catalyst for the asymmetric HDA reaction of isatins with enones for the first time. These dual component systems showed efficient catalytic activities to afford the chiral spirooxindoles that are efficient synthetic intermediates for many biologically active compounds and drug discovery, in good to excellent chemical yields and with enough stereoselectivities. In this study, author revealed that the new explored catalysts component system showed excellent catalytic activity to the asymmetric HDA reaction of isatins with enones. It is expected that this results should be able to greatly contribute the development of new drugs and its related compounds.doctoral thesi
Development of New Organocatalyst Component System for Asymmetric Hetero Diels–Alder Reaction
No full textapplication/pdf医薬品をはじめとする多くの生物活性化合物は光学活性物質であり, その鏡像異性体は薬と毒のような，互いに異なる生体内作用を示すことが多い。そのため，有効な一方の鏡像異性体を高立体選択的に合成するための不斉合成反応の開発，特に不斉触媒を用いる触媒的不斉合成反応の開発は，新薬やキラル機能性分子を創製するために重要である。その不斉触媒の中で，金属を含有しない有機分子触媒は毒性が無く，空気中で安定であり取り扱いやすく安価であるなどの利点を有するため, 次世代の環境調和型触媒として現在活発な研究開発が行なわれている. 光学活性スピロインダノール類は，抗がん，抗 HIVや抗マラリヤ活性などの多彩な生物活性を示すことから，現在そのスピロインダノール骨格を構築するための有機合成反応の開発が活発に行われている。著者は，その合成反応として触媒的不斉ヘテロ ディールス・アルダー反応に着目し，その反応に有効な有機分子触媒複合系を開発することを目的として本研究を行った。著者は，有機分子触媒複合系として，β—アミノアルコールおよびβ—アミノシリルエーテルをそれぞれ触媒とし，アミノ酸を助触媒とするイサチン類とエノン類との不斉ヘテロ ディールス・アルダー反応を検討した。その結果，触媒としてはその分子中に第１級アミノ基や第１級水酸基，またシロキシ基をもつシンプルなキラルβ—アミノアルコールまたおよびβ—アミノシリルエーテルが，また助触媒としてはアミノ基に保護基したα—アミノ酸が本反応中で複合的に触媒活性機能を発現し，優れた化学収率とジアステレオ選択性およびエナンチオ選択性で目的のキラルイサチン誘導体が得られることが明らかとなった。本研究において著者は，光学活性スピロインダノール類の合成に有効な不斉ヘテロ ディールス・アルダー反応に用いる新規有機分子触媒複合系を開発することに成功した。開発した本触媒系は，他の創薬のために有用な不斉触媒反応においても触媒機能を示すことが期待され，さらに，本反応によって得られる光学活性スピロインダノール類は抗がん作用や他の様々な生物活性化合物の合成中間体としても有用であることから，本研究の成果は, 新薬創製を指向した合成開発研究に大きく貢献できると期待される.Many biologically active compounds, including pharmaceuticals, are optically active and often only one of the enantiomer shows a high biologically activity. Therefore, it is important to develop the synthetic methodology for providing only necessary enantiomer. As the methodology, catalytic asymmetric synthesis, in which the use of a low amount of a chiral catalyst theoretically enables infinite production of optically active compounds, is the most efficient in the synthetic organic chemistry field. Moreover, this methodology is also important in terms of energy saving and environmental friendliness. The chiral catalysts used in catalytic asymmetric syntheses can be divided into two categories of organometallic catalyst and metal-free organocatalyst. Particularly, organocatalyst is stable in air, nontoxic, easy to handle, and inexpensive, so they are being focused on as next-generation, environmentally friendly catalysts. Spirooxindoles are considered to be promising scaffolds in drug discovery. The structure of spirooxindoles is contained in many compounds having pharmacological activities such as contraceptive, anti-HIV, anticancer, antituberculosis, antimalarial, and antiproliferative drugs. Therefore, the development of an effective strategy for the preparation of highly optically pure spirooxindoles is a significantly challenging task in research. The hetero Diels–Alder (HDA) reaction is a versatile tool for effectively forming heterocyclic compounds. Especially, the catalytic asymmetric version of this reaction is the most efficient and convenient method for constructing a chiral heterocyclic skeleton, which acts as a precursor for many biologically active compounds and drugs. In this class of HDA reactions, the reaction of isatins with enones is one of the superior organic transformations for providing unique chiral spirooxindoles containing quaternary chiral carbon center on the structure. Author tried to explore new catalysts component system for this reaction using isatins as diene and enones as dienophile. As a result, author developed simple two catalysts component system consisting of primary β-amino alcohol or γ-amino silyl ether as catalysts and N-protected amino acid as a co-catalyst for the asymmetric HDA reaction of isatins with enones for the first time. These dual component systems showed efficient catalytic activities to afford the chiral spirooxindoles that are efficient synthetic intermediates for many biologically active compounds and drug discovery, in good to excellent chemical yields and with enough stereoselectivities. In this study, author revealed that the new explored catalysts component system showed excellent catalytic activity to the asymmetric HDA reaction of isatins with enones. It is expected that this results should be able to greatly contribute the development of new drugs and its related compounds
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
