Dynamic Ligands for Sustainable Molecular Catalysis

用于可持续分子催化的动态配体

• 批准号: RGPIN-2014-05926
• 负责人: Blacquiere, Johanna
• 金额: $ 2.55万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=588702
• 关键词: Dynamic; Ligands; Sustainable; Molecular; Catalysis

The research program, 'Dynamic Ligands for Sustainable Molecular Catalysis', targets innovative catalysts for the synthesis of high-value organic compounds. Advances in catalyst development will be achieved by expanding the fundamental design parameters and principles of cooperative ligands. Transition-metal complexes of these ligands will be exploited in catalytic processes that are highly atom-economic and that use non-toxic and abundant feedstocks (i.e. water, oxygen and first-row metals). Specifically, we target allylic oxidation and hydration reactions. The new catalytic systems will be powerful in applications of organic synthesis in both the academic and industrial realms. Catalysts structures exploit cooperative characteristics, where reactivity at the metal centre is amplified or modulated by a secondary process or functionality. These synergistic relationships include ligands that demonstrate responsive hapticity (dynamic coordination) or second-coordination sphere processes. The latter includes functionalities that participate in hydrogen-bonding or intramolecular proton transfer. These cooperative relationships open new pathways for reactivity or selectivity that are inaccessible through traditional activation of substrates with transition metals. A main objective of this work is to gain a molecular-level understanding of these processes and how they are altered with changes in ligand design. This insight is crucial to the development of high-performance catalysts. The research program is divided between three main research branches. 1) Dynamic Mixed-Donor Ligands for Late-Metal Complexes. We are developing a new ligand family P-AzA that is comprised of a neutral phosphine and an anionic 1-azaallyl fragment. The ligand has the potential to bind to metals in a variety of modes and this coordination shift in response conditions of the system (i.e. introduction of other ancillary ligands or reagents). A thorough understanding of these systems is attained through detailed spectroscopic and reactivity studies, the results of which are necessary for the development of catalytic systems. Catalytic testing of this unique ligand framework is expected to uncover unprecedented activity and selectivity. 2) Selective Oxidation Mediated by Bifunctional Nickel Complexes. Dioxygen is an ideal oxidant and O-atom source as it is highly abundant and, if properly controlled, generates environmentally benign by-products. Control is a major challenge, which can be achieved with uniquely designed metal complexes. We target nickel-NHC complexes that contain hydrogen-bond donors adjacent, but not attached, to the metal centre (NHC = N-heterocyclic carbene). We postulate that these secondary interactions will alter reactivity, diverting away from deactivated or decomposed products. Reactivity studies will provide the groundwork for the development of aerobic oxidation catalysts. 3) High-Performance Catalysts for the Anti-Markovnikov Hydration of Alkynes. Conversion of alkynes to aldehydes with environmentally benign water is 100% atom-economic. Catalytic systems are needed that operate at lower catalyst loadings, lower temperatures and at faster rates. Proton transfer is a key step in the catalytic cycle and is dramatically assisted by ligands that promote intramolecular movement. An extremely promising, but underexploited system is the PR2NR'2 ligand family. Catalytic and stoichiometric studies of several variants (R/R' = Ph, Ar, Cy, Bn, tBu) will uncover the optimal phosphine donor strength and amine basicity for promoting rapid and selective product formation.

该研究项目“可持续分子催化的动态配体”的目标是用于合成高价值有机化合物的创新催化剂。催化剂开发的进步将通过扩展合作配体的基本设计参数和原理来实现。这些配体的过渡金属配合物将用于具有高度原子经济性并且使用无毒且丰富的原料（即水、氧气和第一行金属）的催化过程。具体来说，我们的目标是烯丙基氧化和水合反应。新的催化系统将在学术和工业领域的有机合成应用中发挥强大作用。 催化剂结构利用协同特性，其中金属中心的反应性通过二次过程或功能被放大或调节。这些协同关系包括表现出响应性触觉（动态协调）或第二配位球过程的配体。后者包括参与氢键或分子内质子转移的功能。这些合作关系开辟了新的反应性或选择性途径，这是通过传统的过渡金属底物活化无法达到的。这项工作的主要目标是在分子水平上了解这些过程以及它们如何随着配体设计的变化而改变。这种见解对于高性能催化剂的开发至关重要。 该研究计划分为三个主要研究分支。 1) 后金属配合物的动态混合供体配体。我们正在开发一种新的配体家族 P-AzA，它由中性膦和阴离子 1-氮杂烯丙基片段组成。配体具有以多种模式与金属结合的潜力，并且这种配位在系统响应条件下发生变化（即引入其他辅助配体或试剂）。通过详细的光谱和反应性研究可以全面了解这些系统，其结果对于催化系统的开发是必要的。这种独特的配体框架的催化测试有望揭示前所未有的活性和选择性。 2) 双功能镍配合物介导的选择性氧化。分子氧是一种理想的氧化剂和氧原子源，因为它含量丰富，如果控制得当，会产生对环境无害的副产品。控制是一项重大挑战，可以通过独特设计的金属配合物来实现。我们的目标是含有与金属中心相邻但未连接的氢键供体的镍-NHC 配合物（NHC = N-杂环卡宾）。我们假设这些次级相互作用将改变反应性，远离失活或分解的产物。反应性研究将为有氧氧化催化剂的开发提供基础。 3) 炔烃反马可夫尼科夫水合的高性能催化剂。使用环境友好的水将炔烃转化为醛是 100% 原子经济的。需要能够在较低催化剂负载、较低温度和较快速率下运行的催化系统。质子转移是催化循环中的关键步骤，并得到促进分子内运动的配体的大力协助。 PR2NR'2 配体家族是一个非常有前途但尚未充分开发的系统。几种变体（R/R' = Ph、Ar、Cy、Bn、tBu）的催化和化学计量研究将揭示促进快速和选择性产物形成的最佳膦供体强度和胺碱度。