巻号一覧
49 巻, 8 号
選択された号の論文の9件中1～9を表示しています
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大和田 智彦, 首藤 紘一1991 年 49 巻 8 号 p. 704-720
発行日: 1991/08/01
公開日: 2010/04/23
ジャーナル フリーStable carbocations do not react with non-activated benzenes. The electrophiles, which can react with benzene, are reactive carbenium ions (> C+-X), substituted with a genuine electron-withdrawing group (-X), wherein the substituent X represents carbenium, oxonium, ammonium, O-protonated hydroxylamino, O-protonated N, N-dihydorxylamino, and trifluoromethyl. Experimental evidences, including spectroscopic ones, demonstrated the involvments of these cationic species as discrete reaction intermediates. In this context, a dicationic or tricationic species may participate in various cationic reactions such as the Gatterman-Koch, Pomeranz-Fritsch, Skraup, Bischler-Napieralski and other conventional reactions. Reinvestigations of these reactions should have important implications for the chemistry of Friedel-Crafts and related reactions.抄録全体を表示PDF形式でダウンロード (1790K) -
山崎 孝, 北爪 智哉1991 年 49 巻 8 号 p. 721-736
発行日: 1991/08/01
公開日: 2010/01/28
ジャーナル フリーSince fluorine-containing molecules have been recently disclosed their high ability as pharmaceutically active compounds and optical devices, development of new methods are strongly required for the construction of especially, trifluoromethylated molecules in a highly diastereoselective manner. In this article, with pointing out special problems in the field of fluorine chemistry and explaining the reason why the authors reached to the idea to employ building blocks as one of the promising solution to the above problem, our recent results for the stereoselective preparation of chiral materials via organic, enzymatic, and catalytic antibody methodologies, respectively, are discussed in detail.抄録全体を表示PDF形式でダウンロード (1754K) -
野田 毅, 平間 正博1991 年 49 巻 8 号 p. 737-747
発行日: 1991/08/01
公開日: 2010/01/28
ジャーナル フリーConstruction of hexahydrobenzofuran moiety with both the correct stereochemistry and the C3-C4 double bond is the most important and challenging aspect in the total syntheses of the antiparasitic avermectins and the milbemycins, because this structure, prone to undergo C2-epimerization, double bond-migration, and dehydration, is essential for their biological activity. Successful total syntheses reported thus far have adopted secure strategies introducing the crucial 3, 4-double bond at the final stages after constructing the whole macrolactone structure but they are still less than satisfactory in terms of stereo-and regio-control. We have succeeded for the first time in the straightforward synthesis of the genuine seco-acid possessing the 3, 4-double bond via an oxetane acetal intermediate and have demonstrated that its macrolactonization to milbemycin α1, can be executed without the serious isomerization.抄録全体を表示PDF形式でダウンロード (1246K) -
イムノフィリンと, その免疫抑制剤リガンドの化学と生物学中塚 正志, Stuart L. SCHREIBER1991 年 49 巻 8 号 p. 748-761
発行日: 1991/08/01
公開日: 2010/01/28
ジャーナル フリーAsymmetric syntheses of FK 506 and (C8, C9-13C2) -FK 506 are reported. The latter compound was designed to facilitate an investigation of the interactions between FK 506 and its receptor, the recently discovered immunophilin, FKBP. The synthesis involved the preparation of intermediates 7-9 in nonracemic forms. The key coupling reactions included a Cram-selective addition of the vinyl Grignard reagent derived from bromide 9 to aldehyde 8 and the addition of the lithioanion of phosphonamide 7 to aldehyde 43, followed by thermal elimination. Dithiane 44 was then hydrolyzed, and glycolic ester 6 (or 6*) was added via an aldol reaction that allowed the introduction of 13C labels at C8 and C9. Elaboration to FK 506 proceeded via a Mukaiyama lactamization reaction and a selective deprotection/oxidation sequence, the efficiency of which was critically dependent upon the order of protecting group removal.
13C labeled FK 506 (2) -FKBP drug protein complex was examined by 13C NMR ; the experiments did not show an enzyme bound tetrahedral intermediate, but revealed a noncovalent, fully reversible interaction of the drug with its receptor.
Also delineated are the recent researches aiming at understanding the structural basis for the molecular recognition of immunosuppressants by immunophilins and the biological consequences of their interactions.抄録全体を表示PDF形式でダウンロード (1479K) -
小宮山 真1991 年 49 巻 8 号 p. 762-769
発行日: 1991/08/01
公開日: 2009/11/16
ジャーナル フリーHighly active catalysts for the hydrolysis of phosphodiester linkage in RNAs and DNAs, which are applicable to artificial ribonucleases and nucleases, have been reported. Oligoamines such as ethylenediamine and triethylenetetramine (trien), as well as cobalt (III) complexes such as [Co (trien) (H2O) 2] 3+ and [Co (tme) 2 (H2O) 2] 3+ (tme : 1, 1, 2, 2-tetramethylethylenediamine), are so active (105 to 106 fold acceleration) that RNAs are promptly hydrolyzed near neutrality. The large activities are ascribed to intramolecular acid-base cooperation in the catalysts. In addition, pheophorbide, a derivative of chlorophyll, efficiently cleaves DNAs under irradiation of visible light, even in the absence of oxygen. The photocleavage proceeds via a novel mechanism, which involves direct attack of the dye to DNAs (and not attack by singlet oxygen). Simple structures of these catalysts as well as their large activities strongly indicate high potentialities as the catalytic sites in artificial ribonucleases and nucleases.抄録全体を表示PDF形式でダウンロード (1079K) -
深海 浩1991 年 49 巻 8 号 p. 770-774
発行日: 1991/08/01
公開日: 2009/11/16
ジャーナル フリーPDF形式でダウンロード (800K) -
金谷 茂則1991 年 49 巻 8 号 p. 775-779
発行日: 1991/08/01
公開日: 2009/11/16
ジャーナル フリーPDF形式でダウンロード (810K) -
阿部 好夫1991 年 49 巻 8 号 p. 780-781
発行日: 1991/08/01
公開日: 2009/11/16
ジャーナル フリーアセトアセトアニリドは, 古くから染顔料の有用な中間体として知られ, 今日まで使用されてきた。その化学構造中のベンゼン環がクロロ基, メチル基, メトキシ基などで置換されたアセトアセトアニリドの各種誘導体も共に工業的に生産されているが, 中でもベンゼン環に置換基のないアセトアセトアニリドが代表的であり, 生産量も最も多い。
アセトアセトアニリドは, IUPAC命名法に準拠すると, 3-オキソ-N-フェニル-ブタンアミドと呼ばれ, 現在, わが国では, 年間約600トン (平成元年度推定) が生産され, 主として, 黄色系染顔料の製造に使用されている。抄録全体を表示PDF形式でダウンロード (200K) -
山崎 孝, 中塚 正志, 小宮山 真1991 年 49 巻 8 号 p. 782
発行日: 1991/08/01
公開日: 2009/11/16
ジャーナル フリーPDF形式でダウンロード (160K)
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