巻号一覧
58 巻, 3 号
選択された号の論文の6件中1～6を表示しています
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桑嶋 功, 草間 博之2000 年 58 巻 3 号 p. 172-182
発行日: 2000/03/01
公開日: 2010/01/22
ジャーナル フリーAiming at the construction of taxane ABC tricarbocycles, a useful methodology including an aldol-like eight-membered B ring cyclization between dienol silyl ethers and acetals was explored. By applying this methodology, the enantioselective total synthesis of (+) -taxusin and (-) -taxol have been achieved, starting from the substrate containing a chiral center at each C 1 site, based on AC to ABC strategies.抄録全体を表示PDF形式でダウンロード (1630K) -
丸本 真志, 古源 寛2000 年 58 巻 3 号 p. 183-191
発行日: 2000/03/01
公開日: 2009/11/13
ジャーナル フリーA total synthesis of the neuritegenic agent, epolactaene has been achieved via a convergent approach in 14 steps from optically active lactaldehyde derivatives. The key steps include (i) the stereoselective aldol reaction between malonate ester enolate and α-alkoxy aldehyde (ii) diastereospecific lactonization of malonate ester (iii) E-selective Wittig reaction. The optical rotation was identical with that of the natural (+) -epolactaene, which establishes that the absolute configuration of natural (+) -epolactaene is (13R, 14R) definitively. Other several epoxy-γ-lactam compounds also synthesized which suggest this method would be general for organic synthesis.抄録全体を表示PDF形式でダウンロード (1381K) -
安原 明登, 笠野 篤, 坂本 尚夫2000 年 58 巻 3 号 p. 192-198
発行日: 2000/03/01
公開日: 2009/11/13
ジャーナル フリーA highly reactive nickel powder like Rieke's nickel can be prepared by electrolysis of a DMF solution containing 0.3 mol·dm-3 Bu4NBF4 or 0.3 mol·dm-3 Et4NBF4 in an undivided cell with a platinum cathode and a nickel anode without massive deposition onto the cathode at a constant current of 10 mA/cm2 at 0 °C under an argon atmosphere. The transmission electron micrograph of the electrochemically generated nickel powder shows the particle size to be 2-3 nm. The Ullmann-type reaction of aryl halides with the reactive nickel proceeded with approximately the same yields as those using Rieke's metal. Therefore, the electrochemically generated nickel powder has enough activity for reduction of nitrobenzenes and deallylation of allyl aryl ethers. These reactions proceeded without affecting various functional groups at room temperature in a short reaction time.抄録全体を表示PDF形式でダウンロード (1436K) -
辻 康之, 大洞 康嗣2000 年 58 巻 3 号 p. 199-207
発行日: 2000/03/01
公開日: 2009/11/13
ジャーナル フリーSome homogeneous transition metal catalysts are highly active to cleave σ-bonds between group 14 elements under mild reaction conditions. Various unsaturated compounds insert into the a-bonds to afford a wide variety of products having the group 14 elements. We have utilized silylstannanes (Si-Sn), disilanes (Si-Si), and distannanes (Sn-Sn) in the presence of a transition metal catalyst to realize 1, 4-silylstannation of 1, 3-dienes, 1, 2-silylstannation of olefins, dimerization and bis-silylation of 1, 3-dienes, 1, 4-carbosilylation of 1, 3-dienes, silylation of allylic esters, and bisstannylation of 1, 3-dienes. The structures and fluxional behavior of cis-bis (stannyl) bis (phosphine) platinum, cis-bis (silyl) bis (phosphine) platinum, and cis-bis (stannyl) bis (phosphine) palladium complexes were examined. In the fluxional process, all the spin-spin couplings are retained. The fluxionality is attributed to unimolecular twist-rotation via a pseudotetrahedral transition state.抄録全体を表示PDF形式でダウンロード (1381K) -
豊田 耕三, 吉藤 正明2000 年 58 巻 3 号 p. 208-217
発行日: 2000/03/01
公開日: 2010/04/23
ジャーナル フリーReactions of sterically hindered primary phosphines with elemental sulfur or selenium are reviewed. (2, 4, 6-Tri-t-butylphenyl) phosphine reacted with an excess amount of elemental sulfur in the presence of a catalytic amount of base to give the corresponding dithioxophosphorane via the phosphine sulfide. Dithioxophosphoranes and diselenoxophosphoranes bearing the 2, 4-di-t-butyl-6- (dialkylamino) phenyl group were prepared by a similar method. These compounds are more stable than the corresponding 2, 4, 6-tri-t-butylphenyl derivatives. Deselenation reaction of stabilized (selenoxo) (thioxo) phosphoranes and diselenoxophosphoranes afforded thioxophosphines and selenoxophosphines, respectively. On the other hand, reaction of (2, 4-di-t-butyl-6- methoxyphenyl) phosphine with sulfur gave trans- and cis-1, 3, 2, 4-dithiadiphosphetane-2, 4-disulfides via dithioxophosphorane. The monomeric form of dithioxophosphorane, which can be generated from dithiadiphosphetane disulfides by heating, reacted with benzophenone to give thiobenzophenone. (2, 4-Di-t-butyl-6-methoxyphenyl) phosphine reacted with selenium to give 1, 2, 3, 5, 7-pentaselena-4, 6, 8-triphosphocane, which was used to convert amides into thioamides.抄録全体を表示PDF形式でダウンロード (1527K) -
草間 博之, 丸本 真志, 安原 明登, 豊田 耕三2000 年 58 巻 3 号 p. 218
発行日: 2000/03/01
公開日: 2009/11/13
ジャーナル フリーPDF形式でダウンロード (229K)
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