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Development of Asymmetric Reactions Catalyzed by Metal-Encapsulated Chiral Polysiloxane Gels

金属包封手性聚硅氧烷凝胶催化不对称反应的进展

基本信息

批准号：
18550095
负责人：
MOTOYAMA Yukihiro
金额：
$ 2.55万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

Immobilization of molecular catalysts on solid supports is an important approach in organic synthesis directed towards environmentally benign reaction processes. We have recently found that the metal-encapsulated polysiloxane gels ([M]@Si-O) are formed by Ru and Pt-catalyzed deoxygenative reduction of carboxamides with polymethylhydrosiloxanes (PMHSs) and catalyst species in the gels are still active towards deoxygenative reduction of carboxamides by addition of hydrosilanes. The purpose of this research is development of practical processes for stereo- and chemoselective organic transformations using catalyst-immobilized organogels. Ru and Pt-encapsulated polysiloxane gels (M@Si) were synthesized by treatment of PMHS with diols and dienes as a bridging reagent in the presence of transition metal complexes having dehydrogenative silylation or hydrosilylation activity. Triruthenium carbonyl cluster-encapsulated polysiloxane gels cross-linking with ethylene glycol or biphenol ([Ru_3]@Si-EG or ([Ru_3]@Si-BP) showed catalytic activity towards isomerization of alkenes. Double bond isomerization of allyl or homoallyl ethers using the present method followed by hydrolysis provided a practical method for deprotection of allyl and homoallyl ethers. Pt-encapsulated polysiloxane gel cross-linking with 1,5-hexadiene ([Pt]@Si-C_6) acted as efficient and reusable catalysts for nitro-selective reduction of functionalized nitroarenes. This procedure was applicable to production of anilines in gram-quantities. In these two cases, the product is separated from the gel catalyst by simple extraction, and catalyst species is not detectable in the product.

在固体载体上固定化分子催化剂是实现环境友好型有机合成反应的重要途径。我们最近发现，Ru和pt催化聚甲基氢硅氧烷（pmhs）对羧酰胺的脱氧还原形成了金属包封的聚硅氧烷凝胶（[M]@Si-O），并且凝胶中的催化剂种类对氢硅烷的加入对羧酰胺的脱氧还原仍然有活性。本研究的目的是开发立体和化学选择性有机转化的实际过程，使用催化剂固定化有机凝胶。在具有脱氢硅氧烷化或氢硅氧烷化活性的过渡金属配合物的存在下，以二醇和二烯为桥接剂对PMHS进行处理，合成了Ru和pt包封的聚硅氧烷凝胶（M@Si）。三钌羰基包封聚硅氧烷凝胶与乙二醇或双酚([Ru_3]@Si-EG或（[Ru_3]@Si-BP）交联，对烯烃异构化具有催化活性。采用本方法对烯丙基或同丙烯醚进行双键异构化，然后进行水解，为烯丙基和同丙烯醚的脱保护提供了一种实用的方法。聚乙烯包封聚硅氧烷凝胶与1,5-己二烯（[Pt]@Si-C_6）交联，作为高效可重复使用的催化剂用于硝基化硝基芳烃的硝化选择性还原。本方法适用于克级苯胺的生产。在这两种情况下，产品通过简单的萃取从凝胶催化剂中分离出来，并且在产品中检测不到催化剂的种类。