巻号一覧
54 巻, 8 号
選択された号の論文の8件中1～8を表示しています
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草間 博之, 奈良坂 紘一1996 年 54 巻 8 号 p. 644-653
発行日: 1996/08/01
公開日: 2009/11/16
ジャーナル フリーApplication of rhenium complexes to organic synthesis has progressed rapidly in 1990's. In this review are summarized the recent advances in synthetic reactions catalyzed or promoted by rhenium complexes.
In the first half were described the reactions with high valent rhenium-oxo species. Methyltrioxorhenium catalytically promotes the oxidation of olefins, aromatic rings, and hetero atoms with hydrogen peroxide. The combined use of tetrabutylammonium perrhenate and a Brønsted acid catalyzes the 1, 3-rearrangement of allylic alcohols, the Beckmann rearrangement, and the cyclization of benzylacetone oxime derivatives.
In the latter half, low valent rhenium-catalyzed reactions were summarized. A chiral rhenium cationic compound readily forms the complexes with olefins and carbonyl compounds in high enantiofacial selectivity. The asymmetric hydrocyanation of aldehydes and the alkylation of quinolines or isoquinolines are developed by diastereoselective addition of nucleophiles to these chiral complexes. Bromopentacarbonylrhenium acts as an efficient Lewis acid, realizing the catalytic Friedel-Crafts acylation of arenes with acyl chloride.抄録全体を表示PDF形式でダウンロード (1140K) -
市川 淳士1996 年 54 巻 8 号 p. 654-664
発行日: 1996/08/01
公開日: 2009/11/16
ジャーナル フリーFluorine has remarkable electronic effects and leaving-group ability as fluoride ion. Paying particular attention to the use of these properties in organic synthesis, we discuss the preparation of gemdifluoroolefins and their synthetic applications. gem-Difluoroolefins with a wide range of substituents are synthesized from commercially available 2, 2, 2-trifluoroethyl p-toluenesulfonate (1), wherein the two processes are included : (i) a boron-mediated alkylation leading to gem-difluorovinylboranes 4, and (ii) a variety of their direct functionalizations via gem-difluorovinylcoppers 5. This methodology provides a useful synthetic route to unsymmetrically disubstituted difluoroolefins via the introduction of difluorovinylidene unit (CF2=C). The obtained difluoroolefins readily undergo addition-elimination, cycloaddition-elimination, and cationic cyclization-elimination processes leading to new synthetic reactions. Regiocontrolled syntheses of fluorinated heterocycles, hetero Diels-Alder reactions, fluorine directed Nazarov cyclizations, Friedel-Crafts cyclizations, and tandem cyclizations in their combination are achieved to construct highly functionalized and/or fused ring systems. Throughout these reactions, fluorine substituent functions as an activator of the substrates and a controller over the reaction pathways.抄録全体を表示PDF形式でダウンロード (1406K) -
山崎 孝, 北爪 智哉1996 年 54 巻 8 号 p. 665-674
発行日: 1996/08/01
公開日: 2009/11/16
ジャーナル フリーフッ素を有する有機化合物は, 現在では医農薬を始めとする各種生理活性物質や, 強誘電性液晶材料を代表例とする光学材料など, いわゆるファインケミストリー分野では欠くことのできない物質群を構成しており, こうした事実を改めて指摘するまでもないほどに一般有機化学者の間に浸透してきているといっても過言ではない。その結果, 通常の炭化水素の場合と同様, 高度に位置や立体, 官能基選択的な反応を行うことが当然のように要求されるようになってきている。フッ素化合物を扱った経験のない読者なら, “炭化水素でわかっている方法をそのまま応用すればよいのでは” と思われるかもしれないが, なかなかそううまくいかないのがフッ素化学の常である。フッ素は, その立体的な大きさからしばしば水素と比較されるが (van der Waals 半径 (以下vdW半径と略す) で比較すると, フッ素は1.47Å, 水素は1.20Åである), 全原子中で最大の電気陰性度を示し, かっ3組のローンペアが原子核を高度に遮閉しているようなフッ素の電子的環境は, 水素のそれとは非常に異なっている。
このようなフッ素の電子的特異性からは, 当然のことながらLewis塩基としての性質が期待される。特に最近の有機化学では, 反応剤として有機金属種を使用することが非常に多いため, フッ素化合物と各種金属との相互作用といったトピックスは, 反応経路を構築していくうえで考慮に入れておかなければならない最重要事項の1つである。なぜなら, フッ素と比較的親和性の高い金属のβ位にこの原子が位置する場合には, フッ素自体が脱離基であるためにβ脱離が容易に進行してしまうからである。こうした例は, 金属として汎用されているリチウムやナトリウム, マグネシウムなどの場合によく見られるが, 金属が亜鉛である場合には安定に存在することが多いようである。
さて, これまでに “フッ素化合物をいかにして合成していくか” という観点からまとあられた総説はいくつかあるものの, “プロトンや金属存在下でのフッ素のLewis塩基としての性質” に焦点を当てて書かれたものが見当たらなかったので, 以下に筆者の解釈などを交えながら, H…F間の相互作用である水素結合とF…金属間の相互作用に分けて概観していくことにする。抄録全体を表示PDF形式でダウンロード (1347K) -
柏村 成史, 石船 学, 村井 義洋1996 年 54 巻 8 号 p. 675-685
発行日: 1996/08/01
公開日: 2009/11/16
ジャーナル フリーSome synthetic electroorganic reactions promoted by chemically reactive electrodes (CRE) have recently been exploited and CRE is one of the most attractive new techniques in electroorganic chemistry (EOC). Altohugh the definition of CRE is not always clear at present, the role of electrode in CRE method is quite different from that in the conventional EOC. Namely, the role of electrode in the conventional EOC is generally just a donor or acceptor of an electron and it is not involved in the organic reaction as a reagent. On the other hand, in CRE method, some electrode mterials made of chemically reactive materials such as Mg, Al, and Zn are involved in the reaction as reagents and promote unique reactions which are not attained under the usual conditions of EOC. In this article some synthetic reactions using CRE are described, and the main contents of the article are as follows : 1) Electroreuction of aliphatic ester and amide and related C-C bond forming reactions, 2) Si-Si and Ge -Ge bonds formation reactions and their application to the synthesis of ploysilane and polygermane high polymers, 3) Coupling of dienes and styrenes with aliphatic esters, 4) Reduction of aromatic compounds, 5) Generation of highly reactive metals (Electrogenerated metals).抄録全体を表示PDF形式でダウンロード (1170K) -
千葉 一裕, 多田 全宏1996 年 54 巻 8 号 p. 686-695
発行日: 1996/08/01
公開日: 2009/11/16
ジャーナル フリーUnstable intermediates were generated in situ by electrochemical oxidation of phenolic compounds to give varied cycloadducts with dienes or alkenes by using hydrophobic fields in the reaction system. In an aqueous medium, Diels-Alder reactions of quinones and dienes were markedly prometed in the presence of sodium dodecylsulfate (SDS). Electrochemical generation of unstable quinones and subsequent cycloaddition reactions with varied dienes were mediated by SDS micelle. These electrolytic reactions were also accomplished in a conductive lithium perchlorate/nitromethane system in which Diels-Alder reactions were highly promoted. In this non-aqueous reaction system, electrochemical generation and cycloaddition reactions of ο-quinone methides and unactivated alkenes were also successful to give chroman and spirochroman skeletons which have been proven to be difficult to yield in usual methods. The electrolysis in the lithium perchlorate/nitromethane system was further applied to the proposed biomimetic cycloaddition of ο-quinone methides and terpenes to give natural euglobal skeletons.抄録全体を表示PDF形式でダウンロード (1539K) -
川島 隆幸1996 年 54 巻 8 号 p. 696-707
発行日: 1996/08/01
公開日: 2009/11/16
ジャーナル フリーPentacoordinate oxaphosphetanes, oxasiletanides, oxagermetanides, oxastannetanides, and tetracoordinate oxaboretanides were successfully synthesized as stable intermediates of the Wittig reaction, the Peterson reaction, Peterson-type reactions, and boron-Wittig reaction, respctively Tetracoordinate and pentacoordinate oxathietanes, tetracoordinate oxaselenetanes and pentacoordinate azaphosphetidines were also synthesized as their sulfur and selenium-analogs, and aza-analog of oxaphosphetanes. The X-ray crystallographic analyses of Si, Ge, P, S, and Se compounds indicated that they have a distorted trigonal bipyramidal structure with two apical oxygen atoms, but those of B, Sn, and another type of Ge compounds demonstrated that they have a very distorted tetrahedral boron, a nearly square pyramidal tin, and a tetrahedral germanium strongly interacting with an oxido anion, respectively. Expectedly, on heating all compounds containing group 13, 14, and 15 elements underwent the Wittig-type reaction to give the corresponding olefins. Although the thermolysis of oxachalcogenetanes with a tetracoordinate and pentacoordinate S and Se centers gave no olefin, it was suggested that the former compounds are intermediates of the Corey-Chaykovsky reaction of sulfur ylides.抄録全体を表示PDF形式でダウンロード (1472K) -
高畑 廣紀1996 年 54 巻 8 号 p. 708-711
発行日: 1996/08/01
公開日: 2009/11/16
ジャーナル フリーPDF形式でダウンロード (530K) -
草間 博之, 山崎 孝, 千葉 一裕, 川島 隆幸1996 年 54 巻 8 号 p. 712
発行日: 1996/08/01
公開日: 2009/11/16
ジャーナル フリーPDF形式でダウンロード (183K)
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