巻号一覧
49 巻, 7 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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宇根山 健治1991 年 49 巻 7 号 p. 612-623
発行日: 1991/07/01
公開日: 2009/11/16
ジャーナル フリーTrifluoromethylated compounds have accepted great attention because of their unique nature for material sciences and biological activities for medicines and agrochemicals. Recent advances in trifluoromethylation which include chemical and electrochemical trifluoromethylations and synthetic blocks for trifluoromethylated compounds are summarized.抄録全体を表示PDF形式でダウンロード (1291K) -
永井 隆文, 熊懐 稜丸1991 年 49 巻 7 号 p. 624-635
発行日: 1991/07/01
公開日: 2010/01/28
ジャーナル フリーTrifluoromethyl carbonyl compounds were found to react as a good enophile due to the high electronegativity of a trifluoromethyl group. Thus, hexafluoroacetone reacts with terminal olefins without a catalyst, while other trifluoromethyl ketones and trifluoroacetaldehyde are less reactive and react only in the presence of Lewis acid. Interestingly, an inner olefin, 2-octene, hardly reacts with hexafluoroacetone, while it reacts with other trifluoromethyl carbonyl compounds in moderate to good yields. This inversion of the order of reactivity is explained by a large steric effect of the trifluoromethyl group, although it is referred as a “mimic” of a methyl group. It seems to be a little larger than a sec-butyl group. The ene reaction products, trifluoromethylated homoallyl alcohols, are useful intermediates for various types of trifluoromethyl compounds. General procedures for their conversion to trifluoromethylated dienes, tetrahydrofurans, and tetrahydropyrans are introduced. Products from trifluoroacetaldehyde were oxidized to trifluoromethyl ketones, Grignard and Wittig reactions of which are also discussed from the view point of reactivity and steric effect of a trifluoromethly group. Further, application of this reaction for the synthesis of fluorine analogues of natural products, p-and m-menthane derivatives, are presented.抄録全体を表示PDF形式でダウンロード (1454K) -
藤原 尚, 古川 尚道1991 年 49 巻 7 号 p. 636-646
発行日: 1991/07/01
公開日: 2009/11/16
ジャーナル フリーDications bonded by two positively charged heteroatoms have received a little attention, and study of their properties is of great interest. This article presents the preparation, structure, and properties of σ-bonded dications from the medium-sized cyclic compounds containing S, Se and Te atoms. Both the oxidation of 1, 5-dithiacyclooctane (1, 5-DTCO), the related selenium and tellurium derivatives (1, 5-DSeCO, 1, 5-DTeCO), and their dibenzocyclooctane derivatives using either concd H2SO4 or oxidizing agent such as NOBF4 and the treatment of their monooxide in concd H2SO4 or with (CF3SO2) 2O revealed the formation of dications containing transannular bond between two heteroatoms. The structures of the dication salts of 1, 5-DTCO and 1, 5-DSeCO were determined by X-ray crystallographic analysis. These dications act as an oxidant or as an electrophile depending on the added reagents. These new species are of particular interest and become attractive if one could prepare the analogous derivatives bearing multiheteroatoms. As typical example, inspection of the spectrum of the dication of the tris-sulfide, 1, 11- (methanothiomethano) -5 H, 7 H-dibenzo [b, g] [1, 5] dithiocin, and its oxides in concd D2SO4 indicated that the central sulfur atom should have a hypervalent bonding structure composed of two sulfur and two carbon ligands i.e., 10- S-4 (C2S2).抄録全体を表示PDF形式でダウンロード (1227K) -
高純度光学活性物質の調製宇高 正徳, 酒井 貴志, 坪井 貞夫1991 年 49 巻 7 号 p. 647-656
発行日: 1991/07/01
公開日: 2009/11/16
ジャーナル フリーPreparations of optically pure short- to long-chain β-, γ-, and δ-hydroxy acids with R configuration, α-methyl-β-hydroxy acids with anti-2R, 3R configuration, 1, 2-alkanediols with R configuration, and 1-acetoxy-2-alkanols with S configuration are described, by use of asymmetric reduction of the corresponding keto compounds with bakers' yeast. The high optical purity of the products is attributable to the carboxy group in the keto acids and to the substrate specificity of the enzymes involved in the reductions, based on comparison of the keto acids and keto esters as substrates and isolation of the reducing enzymes from bakers' yeast.抄録全体を表示PDF形式でダウンロード (1186K) -
ベンツリシジンA, Bアグリコンの全合成大石 武, 秋田 弘幸1991 年 49 巻 7 号 p. 657-669
発行日: 1991/07/01
公開日: 2010/01/28
ジャーナル フリーOptically active 2-methyl-3-hydroxy propionic acid derivatives which are expected to be useful building blocks for the synthesis of polyoxo-macrolide antibiotics or the related bioactive compounds have been synthesized based on the asymmetric hydrolysis using various industrialized lipases. As an example of synthetic studies using these synthons, a total synthesis of the aglycone of venturicidins A and B is described.
Hydrolysis of water-insoluble substrates with lipases immobilized with celite or prepolymer (ENTP-4000) proceeds even in organic solvent. However improvement of efficiency is required. Thus a new immobilization method was developed. Namely, an aggregate of lipases with various phospholipid analogue whose hydrophobic aliphatic chains are linked by ether bonding was found to catalyze an asymmetric hydrolysis much more effectively than the previous immobilization methods.抄録全体を表示PDF形式でダウンロード (1401K) -
西山 繁, 山村 庄亮1991 年 49 巻 7 号 p. 670-681
発行日: 1991/07/01
公開日: 2009/11/16
ジャーナル フリーRelated to antiviral agents, nucleoside antibiotic oxetanocin-A isolated from culture broth of Bacillus megaterium NK 84-0218 served potent biological activities against such virus strains as HIV, HCMV and HSV. Of interest is the novel oxetanoside moiety (four-membered ring sugar) of this antibiotic which would promise developments of new antiviral agents. We describe herein total synthesis of oxetanocin-A as well as new oxetanose chemistries. Recent progress of nucleoside analogues relevant to oxetanocin-A is also included.抄録全体を表示PDF形式でダウンロード (932K) -
オーキシン論争解決の手段としての有機合成森 謙治1991 年 49 巻 7 号 p. 682-686
発行日: 1991/07/01
公開日: 2010/01/28
ジャーナル フリーPDF形式でダウンロード (690K) -
綾部 義治1991 年 49 巻 7 号 p. 687-688
発行日: 1991/07/01
公開日: 2009/11/16
ジャーナル フリービフェノール構造は天然には漆の成分の中にウルシオール2量体 (ビカテコール誘導体) の形で存在することが明らかになっている。
4, 4'-ジヒドロキシビフェニール (以下ビフェノールと略す) がポリマーの分野で注目されるようになったのはビフェノールを構成成分とする全芳香族ポリエステルが押出成型, 射出成型可能なサーモトロピック液晶ポリマーとなり耐熱性, 寸法安定性, 精密成型性にすぐれ高強度, 高弾性率, 耐薬品性, 優れた電気特性等を有するためである。
このようにコモノマーとしてのビフェノールの有用性は古くから知られていたが経済的な合成方法がなく本格的な市場参入はなされていなかった。
最近新プロセスが開発され大量生産が可能になった。抄録全体を表示PDF形式でダウンロード (188K) -
宇根山 健治, 藤原 尚, 古川 尚道, 大石 武1991 年 49 巻 7 号 p. 689
発行日: 1991/07/01
公開日: 2009/11/16
ジャーナル フリーPDF形式でダウンロード (161K)
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