巻号一覧
56 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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中村 正治, 中村 栄一1998 年 56 巻 8 号 p. 632-644
発行日: 1998/08/01
公開日: 2009/11/16
ジャーナル フリーOrganozinc reagents have become extremely important synthetic tools in recent years, and the useful and practical preparative routes to such reagents have been reviewed. The methods have been classified into four broad categories, (1) oxidative zincation method, (2) transmetalation method, (3) halogenzinc exchange, and (4) others. Each categories are subdivided according to the type of organic groups on the zinc atom (alkyl, alkenyl, etc.).抄録全体を表示PDF形式でダウンロード (1766K) -
野崎 京子, 檜山 爲次郎1998 年 56 巻 8 号 p. 645-650
発行日: 1998/08/01
公開日: 2009/11/16
ジャーナル フリーCompletely alternating copolymerization of carbon monoxide with α-olefins proceeds in a highly enantioselective manner using chiral Pd (II) complexes. Here we review the recent development in this area. The completely alternating feature of this copolymerization has been studied by kinetics and theoretical calculations. In order to control the regio- and enantioselectivity of olefin insertion, three kinds of chiral bidentate ligands have been reported : bis (dialkylarylphosphine), bisoxazoline, and phosphine-phosphite. The last one is applicable to the reaction of a wide range of α-olefins, such as aliphatic 1-alkenes and styrene derivatives, affording completely alternating copolymers with almost complete head-to-tail regioselectivity, isotacticity, and enantioselectivity. α, ω-Dienes and allenes also give alternating copolymers. Characteristic features of the chiral phosphine-phosphite-Pd (II) system are discussed in relation to the reaction mechanism and the enantiofacial-descriminating step.抄録全体を表示PDF形式でダウンロード (721K) -
中村 英士1998 年 56 巻 8 号 p. 651-660
発行日: 1998/08/01
公開日: 2009/11/16
ジャーナル フリーMarine micro-algae distribute widely in marine environments and display various interesting biological phenomena such as bioluminescence, red-tide forming, sea-food poisoning through food-chain mechanism and/or specific bio-accumulation, and symbiosis with invertebrates. In a course of our studies on biological origin of paltoxins, well known marine toxins from zoanthid, we have isolated new metabolites from a symbiotic dinoflagellate, Symbiodinium sp., collected from a flat worm and cultured under two different conditions. Structural similarities between zooxanthellatoxins, major metabolites in ES medium, and palytoxins suggested that there exist common biogenetic processes such as polyketide pathway utilizing a glycine starting unit and tetrahydropyrane ring formation. Zooxanthellamine, a major metabolite in f/2 medium, was shown to be structurally related to zoanthid alkaloids, zoanthamines, suggesting algal origin of zoanthamines. Biogenesis of gonyauline, an endogenous period-shortening substance from Gonyaulax polyedra revealed a common metabolic pathway of methionine (methionine cascade) in dinoflagellates. Wide distribution of bioluminescent compounds among marine organisms suggested the presence of unknown processes including specific bio-accumulation and common biogenesis.抄録全体を表示PDF形式でダウンロード (1634K) -
北川 理, 田口 武夫1998 年 56 巻 8 号 p. 661-671
発行日: 1998/08/01
公開日: 2009/11/16
ジャーナル フリーWe report here the results of synthetic organic reactions which proceed under mild conditions through the formation of cationic halocyclization intermediates. In the presence of I2 and collidine or lutidine, α-iodination reactions of unsaturated carboxamides and N-allylic carboxamides proceed in good yields through the activation of α-hydrogens by the formation of cyclic iminium ethers (iodolactonization intermediates). The iodine-mediated method can be also applied to the activation of enamide derivatives ; that is, in the presence of I2, the Diels-Alder reactions of N-allylic enamides which are unreactive dienophiles, proceed in good yield through the formation of the cyclic iminium ether. These activation processes are successfully extended to asymmetric α-iodination of unsaturated carboxamides having homochiral 2, 5-disubstituted pyrrolidine and asymmetric Diels-Alder reaction using novel axially chiral N-acryl anilide. Furthermore, the reactions of p-methoxybenzyl pentenyl ether with NIS and O-pentenyl oxime with NBS resulted in the activation of C-O bond and N-O bond through the formation of cationic haloetherification intermediates, and the following reaction with alcohols and migration of anti-substituent gavep-methoxybenzylation and Beckmann rearrangement products in good yields, respectively.抄録全体を表示PDF形式でダウンロード (1293K) -
清水 真, 藤澤 有1998 年 56 巻 8 号 p. 672-680
発行日: 1998/08/01
公開日: 2009/11/16
ジャーナル フリーWidespread use of homochiral 1, 2-diary1-1, 2-diaminoethanes and 2-amino-1, 2-diarylethanols as chiral auxiliaries coupled with difficulties associated with their preparation prompted us to investigate new methodologies for their syntheses. For the preparation of this highly useful class of compounds, enantioselective imino pinacol coupling of p-anisylbenzal-imine was investigated using Zn-Cu couple in the presence of (+) -camphorsulfonic acid as a chiral auxiliary to give (R, R) -1, 2-diphenylethylenediamine derivative in high enantiomeric purity. Highly enantioselective reduction of 1, 2-bis (p-methoxyphenylimino) -1, 2-diphenylethane was also conducted with 0.5 mol% of the new oxazaborolidine, derived from L-threonine and a stoichiometric amount of BH3· THF, to give 1, 2-diphenylethylenediamine derivative in excellent enantiomeric purity. The subsequent deprotection of nitrogen atoms afforded (R, R) -1, 2-diphenylethylenediamine in enantiomerically pure form. Moreover, the reduction of 1, 2-diaryl-2-benzyloxyiminoethanones conducted using the above oxazaborolidine and BH3 ·SMe2 gave β-imino alcohols chemoselectively in high enantiomeric purity. Subsequent selective reduction of the imino functionality affords either syn- or anti-2-amino-1, 2-diarylethanols in high enantiomeric purity by choosing appropriate reduction conditions.抄録全体を表示PDF形式でダウンロード (1152K) -
カルボニルイリドの自在化 (Tailor-made) 調製法を目指して細見 彰1998 年 56 巻 8 号 p. 681-693
発行日: 1998/08/01
公開日: 2010/01/28
ジャーナル フリーUnprecedented approach to nonstabilized carbonyl ylides can be attained by the following three methods : 1) the 1, 3-elimination of organosilicon compounds under mild and neutral conditions, 2) the generation from iodomethyl silyl ethers promoted by samarium reagents as a reductant, and 3) the reductive metalation of α-chloroalkyl α' -chloroalkyl ethers by samarium and activated manganese reagents followed by 1, 3-elimination of metal halide from the intermediate. The last method is especially attractive for the generation of “Tailor-made” carbonyl ylides bearing not only nonstabilized substituents but also no substituents (the parent carbonyl ylide). Using these novel and synthetically practical carbonyl ylides, it has been elucidated that carbonyl ylides reveals high reactivities toward activated and nonactivated alkenes, alkynes, and a variety of heterodipolarophiles such as compounds including C=O, C=N, C=S, N=N double bonds, and optionally substituted and stereochemically defined tetrahydrofurans, dihydrofurans, dioxolanes, and oxazolidines are conveniently synthesized in a single step.抄録全体を表示PDF形式でダウンロード (1690K) -
中島 庸介1998 年 56 巻 8 号 p. 694-695
発行日: 1998/08/01
公開日: 2010/04/23
ジャーナル フリーオスミウム触媒型不斉ジヒドロキシル化反応は広範な基質に信頼性高く適用できることから有機合成に用いられている。エーディミックス-アルファとベータ (以下AD-mix-αとAD-mix-β) はSharplessが開発したこの高選択的不斉ジヒドロキシル化反応を極めて簡単に行えるように必要素材をプレミックスした商品である。
Chilex社 (Wellesley, MA) からのライセンスをもとにアルドリッチ社 (Milwaukee, WI;日本ではシグマアルドリッチジャパン株式会社) が販売している。抄録全体を表示PDF形式でダウンロード (205K) -
中村 正治, 野崎 京子, 中村 英士, 北川 理, 田口 武夫1998 年 56 巻 8 号 p. 696
発行日: 1998/08/01
公開日: 2009/11/16
ジャーナル フリーPDF形式でダウンロード (168K)
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