巻号一覧
57 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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谷 一英, 山縣 恒明, 片岡 靖隆, 真島 和志1999 年 57 巻 8 号 p. 656-666
発行日: 1999/08/01
公開日: 2009/11/16
ジャーナル フリーPreparations and reactivity of iridium complexes bearing several different kinds of ligands such as peraryldiphosphines, PN hybrid ligands, and an optically active chelated diamine and their application to catalysis are described. The catalyst system, iridium (I) /BINAP {2, 2'-bis (diphenylphosphino) -1, 1'- binaphthyl} /benzylamine, serves as an efficient asymmetric hydrogenation catalyst of imines in methanol. As the catalyst precursor and the related complex, complexes [IrCl (diphosphine)] 22 (diphosphine= peraryldiphosphine such as BINAP, BPBP {2, 2'-bis (diphenylphosphino) -1, V.-biphenyl}), which have been known as neutral complexes so far and used as catalyst precursors in many catalytic reactions, could be isolated and fully characterized including X-ray analysis of the BINAP complex. These complexes activated easily E-H (E= heteroatom) bonds and gave the corresponding hydride complexes, [{Ir(H) (diphosphine)} 2 (μ-Cl) (μ-ER) 2] Cl, (ER = OMe, OH, OC (= O) Me, OC (= O) Ph, and SPh). The structure of [{Ir (H) (binap)} 2 (μ-Cl) (μ-OMe) 2] Cl (4a) was determined by X-ray analysis. The complex 4a was found to catalyze hydrogenation of alkyne to trans-olefin selectively and the possible reaction pathways are shown on the basis of the isolated complexes related to the reaction intermediates. By employing the PN ligand which shows flexible coordination ability, we have succeeded in direct observation of the reversible intramolecular C (sp3) -H bond activation and estimated thermodynamic and kinetic parameters regarding the fundamental C-H activation reaction. We could isolate both complexes before and after the C-H activation and characterize them completely including the X-ray structures. By applying the concept of the isolobal analogy, we have shown that the rhodium and the iridium complexes bearing an optically active chelated diamine ligand become efficient asymmetric catalysts for asymmetric transfer hydrogenation of ketone.抄録全体を表示PDF形式でダウンロード (1603K) -
大熊 毅1999 年 57 巻 8 号 p. 667-676
発行日: 1999/08/01
公開日: 2009/11/16
ジャーナル フリーHydrogenation of ketones is amongst one of the most important synthetic reactions. This transformation is not only of academic interest, but also of industrial significance because of its simplicity, environmentally friendliness, and economic viability. trans-RuCl2 (phosphine) 2 (1, 2-diamine), when coupled with a strong base in 2-propanol, acts- as the most reactive catalyst for homogeneous hydrogenation of ketones. This reaction, unlike conventional hydrogenation, proceeds selectively at a C=O bond leaving coexisting C=C linkages intact. Furthermore, rapid, highly productive asymmetric hydrogenation of simple ketones has been realized by using trans-RuCl2 [(S) -tolbinap] [(S, S) -dpen] or its optical antipode. When acetophenone is hydrogenated with the complex, the turnover number reaches 2, 400, 000 and the turnover frequency as high as 228, 000 h-1 or 63 s-1. When XylBINAP is used as a chiral phosphine, a wide variety of prochiral ketones are hydrogenated in up to 100% ee. This practical asymmetric hydrogenation will greatly facilitate the synthesis of biologically active compounds and functional materials.抄録全体を表示PDF形式でダウンロード (1338K) -
西沢 麦夫1999 年 57 巻 8 号 p. 677-688
発行日: 1999/08/01
公開日: 2009/11/16
ジャーナル フリーDuring a trip to Indonesia, I came across a tropical fruit, duku. By extraction of the fruit skin, a hair growth active triterpene lansic acid (1) was isolated. In our planned total synthesis of 1, an effective olefin cyclization agent was required, and mercuric triflate (2) was bone. Then we carried out syntheses of a variety of polycyclic terpenoids and investigated the mechanism of biomimetic olefin cyclization. Upon cyclization of geranylgeranyl acetate, we detected chair/boat/chair cyclization products along with chair/chair/chair cyclization in 1 : 5 ratio. On the basis of the observation that the mercuric triflate is stable but still reactive enough in the presence of water, we trapped each cationic intermediate with water by cyclization in aqueous media. This is the first experimental evidence of the stepwise mechanism of olefin cyclization that takes place via conformationally flexible cationic intermediates. In this review we also deal with an approach into the mystery of the steroid biosynthesis, and a synthetic study toward the taxane skeleton by means of mercuric triflate-induced olefin cyclization.抄録全体を表示PDF形式でダウンロード (1463K) -
和田 眞, 三好 徳和1999 年 57 巻 8 号 p. 689-697
発行日: 1999/08/01
公開日: 2009/11/16
ジャーナル フリーThis article presents organic synthesis by using bismuth and tin compounds, especially synthetic organic reaction in aqueous media : (1) A Grignard-type addition of allyl unit to carbonyl compounds containing a carboxyl group by using bismuth trichloride-metallic zinc-allyl bromide. (2) Allylation of aldehydes by using allylic alcohols in the presence of metallic bismuth. (3) A novel aqueous BarbierGrignard-type allylation of aldehydes in a metallic magnesium/bismuth trichloride bimetal system. (4) Allylation of carbonyl compounds by using allyl Grignard reagent and various metallic salts in aqueous media. (5) Allylation of aldehydes by using allyltin compounds in aqueous media. (6) Asymmetric allylation of carbonyl compounds by using tetraallyltin. (7) Bismuth mediated allylation of unprotected carbohydrates. (8) Ether synthesis by using a catalytic amount of bismuth trichloride and triethylsilane. (9) Asymmetric cyanation of aldehydes promoted by a catalytic amount of chiral bismuth compound. (10) Reduction of aldehydes by using tributyltin hydride in methanol or water.抄録全体を表示PDF形式でダウンロード (1126K) -
羽村 敏, 永島 英夫1999 年 57 巻 8 号 p. 698-707
発行日: 1999/08/01
公開日: 2009/11/16
ジャーナル フリーIn this article are summarized general properties, synthesis, reactivity, and catalysis of Group 4 transition metal amide complexes. Thermally robust but moisture sensitive compounds of the type M (NR2) 4 and MYn (NR2) 4-n CM = Ti, Zr, Hf ; R =H, alkyl, aryl ; Y = X (halogens), OR ; n=1-3) are generally synthesized from MX44 and amines or alkali metal amides, by disproportionation reactions of M (NR2) 4 with MY4, or by ligand exchange reactions of M (NR2) 4 and MYn (NR2) 4-n. Since nitrogen atoms in these compounds form both u- and it-donor bonds to the metal center, the amide complexes typically have planar MNR2 units with shorter M-N lengths.
The amide complexes are highly reactive towards carbonyl compounds or Brønsted acids such as cyclopentadiene. These reactions are useful for chemical transformation of carbonyl compounds and synthesis of metallocene derivatives ; some of the latter are excellent catalysts for olefin polymerization.
Besides metallocene derivatives, Group 4 transition metal amide complexes themselves have recently received much attention as catalysts for ethylene and α-olefins and for hydroamination of acetylenes.抄録全体を表示PDF形式でダウンロード (1265K) -
正山 征洋1999 年 57 巻 8 号 p. 708-719
発行日: 1999/08/01
公開日: 2009/11/16
ジャーナル フリーMAb against THCA was produced by fusing hybridoma with splenocytes immunized with THCA-BSA conjugate and mouse myeloma cell. The cross-reaction of anti-THCA MAb against other marihuana compounds was very wide. This ELISA was applied to the biotransformation experiments of marihuana compounds using plant tissue culture.
Anti-ginsenoside Rb1 MAb cross-reacted with only limited to a few ginsenosides. Newly developed Western blotting used anti-ginsenoside Rb1 MAb surveyed only dammaran saponins. Immunoaffinity column made it possible to separate ginsenoside Rbl directly. Compact MAb, scFV against forskolin was prepared from a hybridoma by gene construction, and its expression in E. coli was discussed.
Biosynthetic enzymes, THCA-, CBCA- and CBDA-synthase had been purified from the homogenate of fresh Cannabis plants, respectively. These characterizations were investigated and compared each other. It became evident that CBCA-synthase catalyzed enantiomeric cyclization of CBGA to CBCA.抄録全体を表示PDF形式でダウンロード (1733K) -
石川 佳代, 田村 佳菜1999 年 57 巻 8 号 p. 720-722
発行日: 1999/08/01
公開日: 2009/11/16
ジャーナル フリーPDF形式でダウンロード (263K) -
谷 一英, 大熊 毅, 西沢 麦夫, 和田 眞1999 年 57 巻 8 号 p. 723
発行日: 1999/08/01
公開日: 2009/11/16
ジャーナル フリーPDF形式でダウンロード (164K)
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