巻号一覧
59 巻, 3 号
選択された号の論文の7件中1～7を表示しています
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近藤 輝幸2001 年 59 巻 3 号 p. 170-184
発行日: 2001/03/01
公開日: 2009/11/13
ジャーナル フリーThe development of efficient methods for the selective formation and cleavage of C-C bonds leading to construction of new carbon skeletons catalyzed by transition-metal complexes is a central and challenging subject of modern organic synthesis. Among the various transition-metal complexes, we have recently focused our attention on novel catalytic activity of low valent ruthenium complexes, since ruthenium complexes often show interesting catalytic activity and product selectivity, which are quite different from those with palladium and other transition-metal complexes. Here, we report our recent results of novel catalytic performance of ruthenium complexes for organic synthesis, which include (1) ruthenium-catalyzed novel C-C bond formation using an ambiphilic reactivity of π-allylruthenium complexes as well as the selective cleavage of C-C bonds via β-allyl elimination, (2) ruthenium-catalyzed novel methods for preparation of cyclopentenones via ruthenacycle intermediates, and (3) ruthenium-catalyzed novel transformation of sulfur-containing compounds, which enables simple, selective and general syntheses of vicinal-dithioethers and allylic sulfides.抄録全体を表示PDF形式でダウンロード (2546K) -
大江 浩一, 米原 宏司, 植村 榮2001 年 59 巻 3 号 p. 185-192
発行日: 2001/03/01
公開日: 2009/11/13
ジャーナル フリーThe development of the catalyst which effectively works in an aqueous system is one of the most important subjects in chemistry mainly due to the economical and environmental concerns. Asymmetric reactions using chiral transition-metal catalyst in water as solvent have attracted a great deal of attention. The immobilization of the catalyst in water is attained by the modification of the catalyst with hydrophilic groups. Carbohydrates have many hydroxyl groups as well as chiral centers in their skeletons, which allow us to make desired chiral structures. Our intensive efforts have been directed to design and prepare new water-soluble chiral ligands for catalytic asymmetric syntheses. The water-soluble novel chiral Rh complexes, such as [Rh (α-or β-TRE-HAP) (cod)] BF4 have been prepared from natural α, α-trehalose or β-D-glucose. They are effective catalysts in the asymmetric hydrogenation of various enamides in water. Since these catalysts can be immobilized in the aqueous phase, simple phase separation after the reaction allows us to reuse the aqueous phase involving the catalyst in further reactions. The highly enantioselective hydrogenation of enamides and itaconic acid has been attained under micellar conditions using [Rh (β-TREHAP) (cod)] BF4 and surfactants.抄録全体を表示PDF形式でダウンロード (1334K) -
佐々木 誠, 井上 将行2001 年 59 巻 3 号 p. 193-205
発行日: 2001/03/01
公開日: 2009/11/13
ジャーナル フリーPolyether marine natural products, exemplified by brevetoxins, ciguatoxins, and maitotoxin, present formidable and challenging synthetic targets due to their structural complexity and exceptionally potent biological activities. In order to address the issue of their total syntheses, we have developed new synthetic methodologies and strategies for the construction of medium-sized ether rings and convergent assembly of polyether system. These include (i) a base-induced 7-endo selective cyclization of a hydroxy epoxide, (ii) convergent synthesis of the fused nine-membered ether ring system, featuring an intramolecular reaction of a γ-alkoxyallylsilane with an acetal group and an SmI2-mediated intramolecular Reformatsky reaction, (iii) intramolecular radical cyclization to construct O-linked oxepane ring system, (iv) convergent assembly of polyether frameworks based on B-alkyl Suzuki coupling of cyclic ketene acetal triflates and phosphates, and (v) construction of cyclic ethers from lactones based on Pd (O) -catalyzed carbonylation. These new methodologies and strategies were successfully applied to the synthesis of selected fragments of ciguatoxins and gambierol.抄録全体を表示PDF形式でダウンロード (2049K) -
木原 伸浩, 高田 十志和2001 年 59 巻 3 号 p. 206-218
発行日: 2001/03/01
公開日: 2009/11/13
ジャーナル フリーDue to the marked progress in control of intermolecular interactions that assemble component molecules, directed synthesis of interlocked molecules such as rotaxanes and catenanes has recently developed greatly. This review summarizes the efficient synthesis of interlocked compounds based on hydrogen-bonding interaction. Various synthetic methods including threading followed by end-capping, clipping, slipping, entering, and polyslipping are discussed. Synthesis under thermodynamic control is also discussed. Various amide-based catenanes and rotaxanes have been synthesized using the template effect based on amide-amide hydrogen-bonding or anion-recognition by macrolactam. The strong hydrogen-bonding between cucurbituril and ammonium salts allowed to prepare various structures of catenanes, rotaxanes, and polyrotaxanes. Further, secondary ammonium salts can be captured into the rings of crown ethers consisting at least 24 ring member to give pseudorotaxanes. A wide variety of end-capping techniques have been developed to give crown ether-based rotaxanes. Control of intramolecular hydrogen-bonding interaction in the interlocked compounds are briefly discussed.抄録全体を表示PDF形式でダウンロード (1558K) -
友田 修司, 金野 大助2001 年 59 巻 3 号 p. 219-231
発行日: 2001/03/01
公開日: 2009/11/13
ジャーナル フリーBased on the simple assumption that π-facial diastereoselection should be originated from the difference in the magnitude of the reaction driving force over the two faces of the π-plane, a new theoretical model is proposed for the prediction of faical diastereoselection. According to the Salem-Klopman equation, two quantities - steric effects (1st term) and the spatial extension of frontier orbital of a substrate ketone (3rd term) - are quantitatively evaluated as the π-plane-divided accessible space (PDAS) and the exterior frontier orbital extension density (EFOE density). The latter is obtained by integrating the frontier orbital (LUMO of a ketone) extension over one side of the π-plane in the exterior area of the van der Waals surface of the ketone under the specific criteria that the driving force vector located on the hydride should be maximally directed toward the carbonyl carbon. Numerous cases of facial diastereoselectivity of hydride reduction including ketones with polar substituents, heterocyclic systems, symmetric bi- or tricyclic ketones, imines, iminium ion are successfully explained by these two new simple quantities. These results as well as quantitative evaluation of transition effects (mainly the antiperiplanar hyperconjugative stabilization involving the incipient bond) strongly suggest that the orbital interaction between reactants generated in the initial stage rather than transition state effects must be the essential process of diastereoselection.抄録全体を表示PDF形式でダウンロード (2027K) -
松居 成和, 井上 佳尚, 藤田 照典2001 年 59 巻 3 号 p. 232-240
発行日: 2001/03/01
公開日: 2009/11/13
ジャーナル フリーAs a result of “Ligand-Oriented Catalyst Design” research based on “Fundamentally Active Ligands”, group 4 transition metal complexes having two phenoxy-imine chelate ligands, FI Catalysts, were found to exhibit very high ethylene polymerization activity using MAO as a cocatalyst. Among the complexes, zirconium complexes displayed the highest activity. The maximum activity exceeded 4 ton-PE/mmol-cat ·h at 25°C even under 1 atm of ethylene. This activity corresponds to a catalyst turnover frequency (TOF) value of 42, 900/sec ·atm, the TOF value being, in all likelihood, the largest for not only olefin polymerization but also any other catalytic reaction. Moreover, selecting the cocatalyst as well as changing the ligand structure revealed that the zirconium complexes produced polyethylene of low (Mv; 3 × 103) to exceptionally high (Mv : 5 × 106) molecular weight, while at the same time displaying high activity. Furthermore, FI Catalysts can be easily synthesized, and possess wider range of catalyst design compared with the group 4 metallocene catalysts. These facts indicate that FI Catalysts possess very high potential as a new generation of olefin polymerization catalysts.抄録全体を表示PDF形式でダウンロード (1539K) -
近藤 輝幸, 大江 浩一, 佐々木 誠, 木原 伸浩, 高田 十志和2001 年 59 巻 3 号 p. 241
発行日: 2001/03/01
公開日: 2009/11/13
ジャーナル フリーPDF形式でダウンロード (211K)
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