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Development of Concepts for the Efficient Exploration of Synergistic Effects in Cooperative Bis-Pd(II)-Catalysis

有效探索双-Pd(II)协同催化协同效应概念的发展

基本信息

批准号：
195801780
负责人：
Professor Dr. René Peters
金额：
--
依托单位：
Institut für Organische Chemie (IOC)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2011
资助国家：
德国
起止时间：
2010-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/195801780?language=en
关键词：
Development Concepts Efficient Exploration Synergistic

项目摘要

In recent years, the Peters research group has described the metallocene-based planar-chiral bis-palladacycles FBIP and RuBIP as stereoselective catalysts for different reaction types. For several of these reactions we were able to show by mechanistic studies that the catalysts allow for a cooperative bimetallic activation mode, in which electrophile and nucleophile are simultaneously activated. For 1,4-additions it was found that C-C-bond formations are extraordinarily accelerated by the bimetallic activation and take place almost instantaneously even for the formation of quaternary stereocenters under mild conditions. On the other hand, kinetic and spectroscopic studies have revealed that this bimetallic catalysis can currently not benefit to a maximum level from this remarkable reactivity generated by the cooperative effects, because product inhibition by a bimetallic bridging coordination obviously plays a more important role than for the corresponding monometallic complexes. This tendency substantially reduces the reactivity advantage of bimetallic catalysis and competing monometallic reaction pathways are thus still important, often leading to a significant loss of selectivity. The major goal of the proposed studies is to develop new planar-chiral bimetallic catalysts, which can profit to a considerably larger degree from cooperative effects, resulting in a significantly higher reactivity than with the currently known bismetallacycles. This would allow for shorter reaction times, lower catalyst loadings and a new spectrum of applications. The proposed development could result in catalysts, which might approximate applicability on technical scale and allow for step-economic approaches towards complex chiral building blocks. In order to realize this goal, we will investigate two different concepts, in which product decomplexation should be strongly accelerated by making use of hemilabile donors. The resulting high catalytic activity shall, e.g., be utilized for a step-economic access of oligopeptides, in which functionalized quaternary amino acids are assembled.

近年来，Peters的研究小组已经描述了基于双烯的平面手性双钯环FBIP和RuBIP作为不同反应类型的立体选择性催化剂。对于这些反应中的几个，我们能够通过机理研究表明，催化剂允许合作的催化剂活化模式，其中亲电体和亲核体同时活化。对于1，4-加成，发现C-C-键的形成被α-活化显著加速，并且即使在温和条件下形成季铵立构中心也几乎瞬间发生。另一方面，动力学和光谱研究表明，这种催化剂目前不能受益于最大程度的合作效应所产生的这种显着的反应性，因为产品抑制由一个桥连的协调显然起着更重要的作用比相应的monoclonal配合物。这种趋势大大降低了单核苷酸催化的反应性优势，因此竞争性单核苷酸反应途径仍然很重要，通常导致选择性的显著损失。所提出的研究的主要目标是开发新的平面手性双金属环催化剂，其可以从合作效应中获益到相当大的程度，从而导致比目前已知的双金属环更高的反应性。这将允许更短的反应时间、更低的催化剂负载和新的应用范围。拟议的发展可能会导致催化剂，这可能近似适用于技术规模，并允许逐步经济的方法来实现复杂的手性结构单元。为了实现这一目标，我们将研究两个不同的概念，其中产品解络合应强烈加速利用半不稳定供体。所得到的高催化活性将，例如，可用于分步经济地获得寡肽，其中组装了功能化的季氨基酸。