巻号一覧
65 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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触媒活性種の構造解明を目指して寺田 眞浩2007 年 65 巻 8 号 p. 748-760
発行日: 2007/08/01
公開日: 2010/10/20
ジャーナル フリーWe have developed highly enantioselective carbonyl-ene reactions catalyzed by a chiral titanium complex prepared from optically pure binaphthol (BINOL) and (i-PrO)2TiCl2 in the presence of molecular sieves (MS) 4 A. During the course of the structural elucidation of catalytically active “BINOL-Ti”, MS 4 A employed in the catalyst preparation step was found to function not only as a base to trap HCl but also as H2O donor eventually providing the active “BINOL-Ti”. The effect of counter cations of zeolites was also investigated in the catalyst preparation step. A sufficient content of Na cation in the zeolites is the key for efficient formation of the active “BINOL-Ti”. Direct transformation of BINOL-Ti (Oi-Pr)2 under the influence of the hydrated MS 4 A into the active catalyst was examined, where BINOL-Ti (Oi-Pr) 2 was assembled into the active “BINOL-Ti” primarily composed of μ3-oxo (Ti3O) species via the di-μ3-oxo bridging tetranuclear titanium complex. Although the exact structure of the active “BINOL-Ti” has not yet been determined, we proposed a plausible pathway to the formation of active “BINOL-Ti” from BINOL and (i-PrO)2TiCl2 under the influence of hydrated MS 4 A.抄録全体を表示PDF形式でダウンロード (2138K) -
西林 仁昭, 三宅 由寛, 植村 榮2007 年 65 巻 8 号 p. 761-771
発行日: 2007/08/01
公開日: 2010/10/20
ジャーナル フリーRecent development of optically active chiral ligands, ferrocenyloxazolinylphosphines (FOXAP), and their application to catalytic asymmetric reactions are reviewed. FOXAP have been prepared in high yields from the corresponding chiral oxazolinylferrocenes via diastereoselective lithiation followed by quenching with chlorodiphenylphosphine. They work as chiral ligands quite effectively for a variety of transition metal-catalyzed asymmetric reactions such as hydrosilylation and transfer hydrogenation of ketones and imines, kinetic resolution of alcohols, carbon-carbon bond forming reactions and ring-opening reactions.抄録全体を表示PDF形式でダウンロード (1743K) -
赤井 周司, 北 泰行2007 年 65 巻 8 号 p. 772-782
発行日: 2007/08/01
公開日: 2010/10/20
ジャーナル フリーThe lipase-catalyzed transesterification of alcohols with acyl donors in organic media has gained increased attention as a powerful method for the preparation of optically enriched compounds under very mild conditions, in which the vinyl esters 2 have been most frequently employed as the acyl donors; however, they are not always satisfactory.
We applied the ethoxyvinyl esters 6 to the lipase-catalyzed transesterification reactions for the first time and discovered their advantages, viz., (i) the efficient reactivity and enantiotopic selectivity similar to or higher than those of 2 and (ii) the ready availability of the esters 6 having a suitably functionalized acyl moiety from the corresponding carboxylic acids and their applicability to the enzymatic reactions. These findings have opened a new possibility of the lipase-catalyzed reactions. In this review, several examples are introduced along with some related recent progress on the lipase-catalyzed asymmetric syntheses. The topics include (i) the enantioselective desymmetrization of prochiral 2, 2-disubstituted 1, 3-propanediols using 1-ethoxyvinyl 2-furoate 6b, (ii) the lipase-catalyzed domino reactions using suitably functionalized acyl donors 6e-i for the direct preparation of optically enriched cyclic compounds having multi stereogenic carbon centers, (iii) the dynamic kinetic resolution (DKR) of racemic secondary alcohols by the combined use of lipases and the ruthenium complexes 36a-g, and (iv) the DKR of racemic allylic alcohols (44, 45) by the combination of lipases and the vanadium compound 43. Application of these reactions to the asymmetric total synthesis of natural products is also described.抄録全体を表示PDF形式でダウンロード (1613K) -
秋田 弘幸2007 年 65 巻 8 号 p. 783-794
発行日: 2007/08/01
公開日: 2010/10/20
ジャーナル フリーThis review summarizes the chemoenzymatic syntheses of biologically active natural products based on a combination of chemical diastereoselectivity and enzymatic enantioselectivity using lipase. Both primary alcohols possessing a chiral center at β-position of hydroxyl group and secondary alcohols were subjected to the lipase-assisted acylation in the presence of acyl donor to afford the optically active esters and the optically active alcohols corresponding to the starting material. These optically active compounds were converted to the biologically active natural products such as bisabolane type sesquiterpenes, oudemansins, nikkomycins B and Z, chuangxinmycin, cystothiazoles and melithiazols possessing antifungal and cytotoxicic activities, inhibition of NADH oxidation, etc.抄録全体を表示PDF形式でダウンロード (1712K) -
土井 隆行, 田中 浩士, 高橋 孝志2007 年 65 巻 8 号 p. 795-804
発行日: 2007/08/01
公開日: 2010/10/20
ジャーナル フリーSolid-phase syntheses of combinatorial libraries based on natural products, such as, (i) vitamin D3, (ii) macrosphelide A, (iii) aurilide, (iv) aeruginosin 298-A, (v) trisaccharides, (vi) clavulone, (vii) 15-deoxyPGJ2, (viii) phlorizin, (ix) naltrindole, and (x) norbinaltorphimine are described. The highly convergent synthetic strategies that enable the high-throughput syntheses of their derivatives are also outlined.抄録全体を表示PDF形式でダウンロード (1447K) -
樹林 千尋, 青柳 榮, 阿部 秀樹2007 年 65 巻 8 号 p. 805-819
発行日: 2007/08/01
公開日: 2010/10/20
ジャーナル フリーThe purpose of this review is to describe some of our achievements in the total synthesis of the tricyclic marine alkaloids isolated from the ascidians such as fasicularin, lepadiformine, and cylindricine C. The first total synthesis of (±) -fasicularin and (±) -lepadiformine was accomplished employing a stereocontrolled intramolecular hetero-Diels-Alder reaction of an N-acylnitroso moiety to an exocyclic diene. The synthesis of natural (-) -enantiomer of lepadiformine was then undertaken using a highly efficient protocol involving a new variant of an N-acyliminium ion-initiated intramolecular spirocyclization. These syntheses of lepadiformine led to revision of the published structure of the natural product, formerly assigned incorrectly, and established its absolute stereochemistry to be 2R, 5S, 10S, 13S. The developed strategy based on the spirocyclization was also applied to the total synthesis of (+) -cylindricine C and (-) -fasicularin. The ability of fasicularin to damage DNA by acting as an alkylating agent was investigated.抄録全体を表示PDF形式でダウンロード (2236K) -
鳶巣 守2007 年 65 巻 8 号 p. 820-821
発行日: 2007/08/01
公開日: 2010/10/20
ジャーナル フリーThe oxidation of C-H bonds adjacent to heteroatoms has been known as an efficient method to generate iminium and oxocarbenium ions. However, the method has rarely been applied to the subsequent C-C bond formation reactions. In this short review, recent examples of such C-H oxidation/C-C bond formation reactions are described.抄録全体を表示PDF形式でダウンロード (324K) -
西林 仁昭, 三宅 由寛, 植村 榮, 赤井 周司, 秋田 弘幸, 土井 隆行2007 年 65 巻 8 号 p. 822
発行日: 2007/08/01
公開日: 2010/10/20
ジャーナル フリーPDF形式でダウンロード (188K)
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