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，彼得斯研究小组将基于甲金属的平面 - 手续的双壁球和rubip描述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种，我们能够通过机械研究表明催化剂允许进行双金属激活模式，在这种模式下，亲电的和核心的同时激活了催化剂。对于1,4个成熟，发现C-C键的地层是通过双金属激活极大地加速的，即使是在轻度条件下的第四纪立体中心的形成，也几乎瞬间进行。另一方面，动力学和光谱研究表明，这种双金属催化目前不能从合作效应产生的这种显着反应性中获得最大水平，因为相应的桥接协调抑制产物显然在相应的单元复合物中抑制产物更重要的作用。因此，这种趋势大大降低了双金属催化和竞争单一反应途径的反应性优势仍然很重要，通常会导致选择性显着丧失。拟议的研究的主要目标是开发新的平面双金属催化剂，从合作效应中可以提高其程度的利润，从而使反应性明显高于目前已知的bismetallacycles。这将允许较短的反应时间，较低的催化剂负载和新的应用范围。拟议的开发可能会导致催化剂，这可能会在技术规模上近似适用性，并允许对复杂的手性构建块的步骤经济方法。为了实现这一目标，我们将研究两个不同的概念，在这种概念中，应该通过使用半脂肪供体来强烈加速产品解剖。所得的高催化活性应例如用于寡肽的逐步经济获取，其中组装功能化的四元氨基酸。