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炔烃的反式氢锡化反应选择性位点研究:在 Typhonosides E 和 F 全合成中的应用,以及一个氟代脑苷脂类似物。

Site-Selective trans-Hydrostannation of 1,3- and 1,n-Diynes: Application to the Total Synthesis of Typhonosides E and F, and a Fluorinated Cerebroside Analogue.

机构信息

Max-Planck-Institut für Kohlenforschung, 45470, Mülheim/Ruhr, Germany.

出版信息

Chemistry. 2018 Jul 5;24(38):9667-9674. doi: 10.1002/chem.201801344. Epub 2018 Jun 12.

Abstract

Propargyl alcohols are privileged substrates for stereochemically unorthodox trans-hydrostannation reactions catalyzed by [CpRuCl] (Cp=pentamethylcyclopentadienyl), because an incipient hydrogen bond between the -OH group and the polarized [Ru-Cl] unit assists substrate binding. For this very reason, it is also possible to subject diyne derivatives carrying one -OH group to site-selective stannylation, even if the acetylene units are conjugated and hence, electronically coupled. An unusual temperature dependence was observed in that heating tends to improve site-selectivity, whereas per-stannylation is favored when the reaction is carried out in the cold. This counterintuitive trend can be rationalized based on spectroscopic data; additional support comes from the isolation of the unusual bimetallic complex 11. The bridging fulvene and enynyl ligands in 11 are thought to reflect an interligand redox isomerization process likely triggered by synchronous activation of the 1,3-diyne substrate by two metal centers. The preparative relevance of site-selective trans-hydrostannation is illustrated by the total synthesis of two members of the typhonoside series of glycolipids, which are endowed with neuroprotective properties. Moreover, the preparation of a fluoroalkene sphingosine analogue shows that the tin residue also serves as a versatile handle for late-stage modification of a bioactive target compound.

摘要

炔丙醇是[CpRuCl](Cp=五甲基环戊二烯基)催化的立体化学非常规反氢锡化反应的优势底物,因为-OH 基团和极化[Ru-Cl]单元之间的初始氢键有助于底物结合。正是出于这个原因,即使乙炔单元共轭且因此电子耦合,也可以对带有一个-OH 基团的二炔衍生物进行选择性锡化。观察到不寻常的温度依赖性,即加热倾向于提高选择性,而在低温下进行反应时,则有利于全锡化。这种违反直觉的趋势可以基于光谱数据进行合理化;来自分离出的不寻常的双金属配合物 11 的额外支持。11 中的桥连富烯和烯炔基配体被认为反映了配体间的氧化还原异构化过程,该过程可能是由两个金属中心同步激活 1,3-二炔底物触发的。选择性反氢锡化的制备相关性通过两种糖脂 typhonoside 系列成员的全合成得到了说明,它们具有神经保护特性。此外,氟烯醇神经鞘氨醇类似物的制备表明锡残留物还可用作生物活性靶化合物后期修饰的多功能处理。

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