巻号一覧
57 巻, 6 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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占部 弘和1999 年 57 巻 6 号 p. 492-502
発行日: 1999/06/01
公開日: 2009/11/16
ジャーナル フリーA newly introduced, low-valent titanium complex, (η2-propene) Ti (O-i-Pr) 2 prepared from Ti (O-i-Pr) 4 and 2 equiv of i-PrMgCl in situ, reacted with olefins and acetylenes in an inter- or intra-molecular manner to give mono-or bicyclic dialkoxytitanacycles. Formation of several kinds of the titanacycles and their synthetic applications are described in the following sections : i) olefinolefin cyclization, ii) olefinacetylene cyclization, iii) acetylene-acetylene cyclization, iv) cyclization of allenes, v) cyclization of unsaturated esters, and vi) generation of a low-valent alkoxytitanacycle. The advantageous feature of these new titanacycles over the existing Cp2-metallacycles of group 4 metals in organic synthesis will be highlighted.抄録全体を表示PDF形式でダウンロード (1301K) -
石山 竜生, 宮浦 憲夫1999 年 57 巻 6 号 p. 503-511
発行日: 1999/06/01
公開日: 2009/11/16
ジャーナル フリーTransition metal-catalyzed additions and cross-coupling reactions of the metal-metal compounds have attracted considerable attention as direct routes to prepare various organometallic compounds. Although the corresponding reactions of boron compounds had not yet been well developed, we recently reported the first platinum (0) -catalyzed addition reaction of bis (pinacolato) diboron (1 d) to either terminal or internal alkynes to give cis-bis (boryl) alkenes. The addition of 1 d to 1, 3-dienes and alkenes with platinum (0) complexes afforded a new access to the cis-1, 4-bis (boryl) butene and bis- (boryl) alkane derivatives. The palladium (0) -catalyzed cross-coupling reactions of 1 d with aryl halides or triflates, and allyl chlorides or acetates gave the corresponding aryl- and allylboronates in high yields, which provides the first one-step procedure for organoboronic esters from organic electrophiles. Since (alkoxo) diborons are thermally stable and easily handled in air, the reagent can be useful as boron nucleophiles for cross-coupling reactions with organic halides. The mechanisms and the synthetic applications of those reactions are discussed.抄録全体を表示PDF形式でダウンロード (1145K) -
鹿又 宣弘1999 年 57 巻 6 号 p. 512-522
発行日: 1999/06/01
公開日: 2009/11/16
ジャーナル フリーCoenzyme NAD+/NADH, a major cofactor of dehydrogenases, functions as an autorecycling redox agent in biological systems, which is exemplified by enantioselective reduction of pyruvate to L-lactate and oxidation of glyceraldehyde-3-phosphate to 1, 3-bisphosphoglycerate as is observed in anaerobic glycolysis. This article reviews biomimetic asymmetric reduction and oxidation in NAD+/NADH model systems. The first part outlines highly enantioselective reduction of benzoylformate, a lactate analog, with representative NADH model compounds mimicking biological reduction in lactate dehydrogenase. In this section, the well-developed model reactions are grouped based on the types of NADH models ; one having a chiral center at the C-4 position of its 1, 4-dihydronicotinoyl ring and the other good for recycling use. The latter half describes the detailed history on the less developed biomimetic oxidation with NAD+ model compounds. This section classifies the model reactions based on the types of model substrates to summarize the oxidation of alcohols, aldehydes, and formates into aldehydes (or ketones), carboxylates, and carbon dioxide, respectively, with regioselective formation of the corresponding NADH model compounds as analogous reactions in alcohol-, glyceraldehyde-3-phosphate-, and formate dehydrogenases抄録全体を表示PDF形式でダウンロード (1427K) -
柴崎 剛, 森 英郎, 尾崎 明夫1999 年 57 巻 6 号 p. 523-531
発行日: 1999/06/01
公開日: 2009/11/16
ジャーナル フリーThis article describes microbial proline hydroxylases which carry out regio- and stereospecific hydroxylation of free L-proline and their application to the enzymatic synthesis of hydroxyprolines and related compounds. Proline 4-hydroxylase activities were detected in 8 actinomycetes strains, and proline 3-hydroxylase activities were detected in 3 actinomycetes and 2 Bacillus strains. Both enzymes were purified and characterized. The enzymes required 2-oxoglutarate and Fe2+ for the reaction. Proline 4-hydroxylase hydroxylated L-proline in a regio- and stereospecific manner at C-4 to form trans-4-hydroxy-L-proline, while 3-hydroxylase hydroxylated C-3 of L-proline to form cis-3-hydroxy-L-proline. Efficient biotransformation systems of L-proline to trans-4-hydroxy-L-proline or cis-3-hydroxy-L-proline were established using recombinant DNA technology. Both of the enzymes hydroxylated L-2-azetidine carboxylate, 3, 4-dehydro-L-proline and L-pipecolate in a regio- and stereospecific manner, however, D-proline, N-substituted L-proline, L-proline ester and peptidyl L-proline do not react as substrates for either 4- or 3-hydroxylases.抄録全体を表示PDF形式でダウンロード (1116K) -
白井 隆一1999 年 57 巻 6 号 p. 532-540
発行日: 1999/06/01
公開日: 2009/11/16
ジャーナル フリーCuracin A is a novel antitumor antimitotic agent isolated from a Caribbean cyanobacterium Lyngbya majuscula. Synthesis of the four stereoisomers of (+) -and (-) -2- (2-methyl) cyclopropyl-4- (1-propenyl) thiazoline was achieved to elucidate the absolute configuration of three chiral centers of natural curacin A. Next, the asymmetric total synthesis of curacin A was achieved in high stereoselective manner. 2-Methylcyclopropyl moiety was synthesized by asymmetric double Simmons-Smith cyclopropanation Thiazoline moiety was constructed from L-cycsteine and side chain was synthesized from geraniol. A series of side chain analogs of curacin A were also synthesized to find the minimal and common active structure to colchicine. However, these analogs showed weak or no antitubulin activity suggesting that the side chain of curacin A was restrictly recognized by microtubule proteins.抄録全体を表示PDF形式でダウンロード (930K) -
村山 徹郎1999 年 57 巻 6 号 p. 541-551
発行日: 1999/06/01
公開日: 2009/11/16
ジャーナル フリーElectrophotography is one of the most prevalent copier and printer technologies. Photoreceptors play a major role in the electrophotographic process. Nowadays, organic photoconductive materials have been most widely used for photoreceptors. Azo and Phthalocyanine pigments are major charge carrier generation materials (CGMs). Hydrazones and arylamines are used as charge carrier transport materials (CTMs). Some models for carrier generation and transport mechanisms have been proposed, Based on these models, molecular structural effects of CGMs and CTMs have been investigated and some new compounds showing good performances have been synthesized.抄録全体を表示PDF形式でダウンロード (1464K) -
近藤 輝幸, 光藤 武明1999 年 57 巻 6 号 p. 552-558
発行日: 1999/06/01
公開日: 2009/11/16
ジャーナル フリーThe development of efficient methods for the selective cleavage of carbon-carbon bonds catalyzed by transition metal complexes is a central and challenging subject of modern organic synthesis. Alkene insertion into metal-alkyl bonds has been recognized as a fundamental step in many catalytic reactions. The reverse reaction, i.e., carbon-carbon bond cleavage via β-carbon elimination, has recently received growing attention. Since Watson and Roe reported the first example of β-methyl elimination of (C5Me5) 2LuCH2CH (CH3) 2, several examples of reversible β-alkyl insertion-elimination at both early and late transition metal centers have been reported. Recently, the reactions which involve catalytic carbon-carbon bond cleavage via β-alkyl elimination are in progress. Here, both stoichiometric and catalytic carbon-carbon bond cleavages via β-alkyl elimination as a key step of the reaction are summarized from the synthetic, industrial and environmental point of view.抄録全体を表示PDF形式でダウンロード (856K) -
石濱 泰, 尾崎 明夫, 白井 隆一, 村山 徹郎1999 年 57 巻 6 号 p. 559
発行日: 1999/06/01
公開日: 2009/11/16
ジャーナル フリーPDF形式でダウンロード (154K) -
1999 年 57 巻 6 号 p. 567
発行日: 1999年
公開日: 2009/11/16
ジャーナル フリーPDF形式でダウンロード (123K)
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