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: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=632684
• 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.

这项名为“用于可持续分子催化的动态配体”的研究计划针对的是合成高价值有机化合物的创新催化剂。通过扩展合作配体的基本设计参数和原则，将在催化剂开发方面取得进展。这些配体的过渡金属络合物将被用于原子经济性高、使用无毒和丰富的原料(即水、氧气和第一排金属)的催化过程。具体地说，我们的目标是烯丙基氧化和水合反应。新的催化体系将在学术和工业领域的有机合成应用中发挥强大的作用。催化剂结构利用合作特性，其中金属中心的反应活性被二次过程或功能放大或调节。这些协同关系包括表现出响应性触觉(动态配位)或二次配位球过程的配体。后者包括参与氢键或分子内质子转移的官能团。这些合作关系为反应性或选择性开辟了新的途径，而通过传统的底物与过渡金属的活化是无法实现的。这项工作的一个主要目标是在分子水平上了解这些过程以及它们是如何随着配体设计的变化而改变的。这一见解对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)晚期金属络合物的动态混合施主配体。我们正在开发一个新的配体家族P-aza，它由一个中性膦和一个阴离子1-氮杂烯丙基片段组成。该配体有可能以各种方式与金属结合，这种配位作用改变了体系的反应条件(即引入其他辅助配体或试剂)。对这些体系的透彻了解是通过详细的光谱和反应性研究来获得的，这些研究的结果对于开发催化体系是必要的。对这种独特的配体骨架的催化测试有望发现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。氧气是一种理想的氧化剂和氧原子来源，因为它非常丰富，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络合物来实现。我们的目标是含有氢键施主的镍-NHC络合物，这些给体邻近但不连接到金属中心(NHC=N-杂环卡宾)。我们推测，这些二次相互作用将改变反应性，使其远离失活或分解的产物。反应活性的研究将为有氧氧化催化剂的开发奠定基础。3)高效的烯烃反马氏水合反应催化剂。用对环境友好的水将炔烃转化为醛是100%的原子经济性。催化系统需要在更低的催化剂负载量、更低的温度和更快的速度下运行。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极大帮助。PR2NR‘2配体家族是一个非常有前景但未被开发的系统。几个变种(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。