Synergistic Ligand Effects in Palladium Catalysis

配体作为过渡金属络合物的修饰剂，在有机金属化学和催化中具有重要的作用。这些辅助配体，通常被称为旁观者，对催化剂的活性和寿命有深远的影响。在这个建议中，非常特定的配体类别，即经典的P-供体(PR3，P(OR)3，PR(OR)2，P(R2(OR)与最近使用和开发的N-杂环卡宾(NHC)被建议作为协同伙伴，使已建立的和新的转化成为可能。研究的目标系统包括用于交叉偶联反应的基于钯的混合配体系统。在这一领域已经进行了概念验证实验，并验证了混合配体对催化剂寿命影响的初始假设。围绕钯的各种结构被提出用于合成和催化研究。进一步提出了钯体系在各种重要底物的氢化和转移氢化中的研究。应该指出的是，这种由钯催化的氢化反应很少见，因为还原成钯黑通常是有问题的。这些初步实验验证了本文提出的协同效应，以供进一步研究。支持非对称转换的系统的开发尤其具有针对性。并展望了其在好氧氧化反应中的应用前景。

The role of ligands, as transition-metal complex modifiers, is fundamental in organometallic chemistry and catalysis. These ancillary, often called spectator , ligands have a profound influence on catalyst activity and longevity. In this proposal, very specific ligand classes, namely the classical P-donors (PR3, P(OR)3, PR(OR)2, P(R2(OR)) in combination with the more recently employed and developed N-Heterocyclic carbenes (NHC) are proposed as synergistic partners enabling established and novel transformations. Systems targeted for study include palladium-based mixed ligand systems for cross-coupling reactions. Proof of concept experiments in this area have been conducted and validate the initial hypothesis of mixed ligand effects on catalyst longevity. Various architectures surrounding palladium are proposed for synthetic and catalytic investigation. Further palladium systems are proposed for investigation in hydrogenation and transfer hydrogenation of various important substrates. It should be noted that such hydrogenations mediated by palladium are rare as reduction to palladium black is often problematic. These initial experiments validate the synergistic effect proposed here for further investigation. The development of systems enabling asymmetric transformations is especially targeted. Applications in aerobic oxidation reactions are also envisaged.