Designer Silver Catalysts for Tunable C=C and C-H Bond Amination

用于可调C-H和C=C键胺化的设计银催化剂世纪化学家面临的主要挑战之一是确定廉价和可持续的方法，将从石油和生物可再生资源中获得的物质转化为合成急需的药物、农用化学品、聚合物和燃料的有用结构单元。碳-氢单键（C-H）和碳-碳双键（C=C）是有机化合物中最常见的两种化学键，代表了将新官能团引入这些化合物中的方便位置。然而，难以在单个分子中存在的许多C-H或C=C键中的仅一个特定的C-H或C=C键处实现所需的反应。在这个项目中，Schomaker博士正在开发新的银催化剂，将这些键转化为重要和有用的碳-氮键，产率高，浪费少，并且能够从单一起始化合物中选择性地制备许多不同的有用产品。 研究了解银的独特特征，这些特征能够对这种反应性进行如此高的、可预测的控制，这是设计改进且耐用的催化剂的关键，这些催化剂可以有效地将珍贵的碳氢化合物原料转化为有价值的材料，甚至使用水作为反应溶剂。 Schomaker博士积极参与与她在催化方面的研究兴趣相关的外联计划，以教育和吸引公众，特别是年轻女性参与与科学，技术，工程和数学（STEM）相关的领域。她的活动包括开发以银催化相关主题为中心的实践实验模块，用于“拓展你的视野”，为6- 8年级的女孩提供以STEM为中心的课程，以及为“科学是有趣的”公开演讲提供银化学的娱乐和教育演示。威斯康星州大学的Jennifer Schomaker博士正在开发低成本的模块化催化剂，用于将C-H键可调功能化为有价值的C-N键。这些方法对于药物、农用化学品、手性配体和胺结构单元的简化合成至关重要，但在催化领域代表了一个长期的挑战。为了解决这个问题，Schomaker博士正在寻求对银络合物独特特性的基本理解，这些特性使它们能够通过金属催化的氮宾转移过程实现催化剂控制的C-H键到C-N键的转化。变温（VT）NMR、扩散光谱、机理和计算研究的组合（密度泛函理论和更高水平的从头计算方法如CASSCF）被用来评估N-供体配体的特征如何影响金属氮烯的电子结构，反应中间体在溶液中的动态/流动行为和促进底物/催化剂以影响C-H官能化事件的位点。最终，这项工作是建立通用的设计原则，用于催化剂的合成，促进非定向C-H官能化，能够压倒先天的反应性偏好，可扩展到其他金属和其他C-H氧化反应，特别是在不对称的情况下。Schomaker博士还积极参与一些STEM外展计划，以吸引和教育她所在社区的学生了解催化剂在解决我们社会目前面临的挑战方面的重要性。她特别感兴趣的是增加妇女在STEM学科的代表性，以支持这项工作的更广泛的影响。

Designer Silver Catalysts for Tunable C-H and C=C Bond AminationOne of the major challenges facing chemists in the 21st century is identifying cheap and sustainable ways to transform substances obtained from petroleum and biorenewable sources into useful building blocks for the synthesis of critically needed pharmaceuticals, agrochemicals, polymers, and fuels. The carbon-hydrogen single bond (C-H) and carbon-carbon double bond (C=C) are two of the most common chemical bonds in organic compounds and represent convenient locations to introduce new functionality into those compounds. However, it is difficult to achieve a desired reaction at only one specific C-H or C=C bond of the many that are present in a single molecule. In this project, Dr. Schomaker is developing new silver catalysts that transform these bonds to important and useful carbon-nitrogen bonds with high yields, less waste, and with the ability to selectively make many different useful products from a single starting compound. Studies to understand the unique features of silver that enable such high, predictable levels of control over this reactivity are key to designing improved and durable catalysts that efficiently transform precious hydrocarbon feedstocks into valuable materials, even using water as reaction solvent. Dr. Schomaker is active in outreach programs related to her research interests in catalysis to educate and engage the general public, especially young women, in fields related to science, technology, engineering and mathematics (STEM). Her activities include developing hands-on experimental modules centered on topics related to silver catalysis for "Expanding Your Horizons", a STEM-centered program for girls in 6-8th grades, as well as entertaining and educational demonstrations on silver chemistry for "Science is Fun" public presentations.With funding from the Chemical Catalysis Program of the Chemistry Division, Dr. Jennifer Schomaker of the University of Wisconsin is developing low-cost, modular catalysts for the tunable functionalization of C-H bonds to valuable C-N bonds. Such methods are crucial for streamlined syntheses of pharmaceuticals, agrochemicals, chiral ligands and amine building blocks, but represent a long-standing challenge in the field of catalysis. To address this issue, Dr. Schomaker is pursuing a fundamental understanding of the unique features of silver complexes that enable them to achieve catalyst-controlled transformations of C-H bonds to C-N bonds through metal-catalyzed nitrene transfer processes. A combination of variable temperature (VT) NMR, diffusion spectroscopy, mechanistic and computational studies (density functional theory and higher-level ab initio methods such as CASSCF) are being employed to assess how the features of N-donor ligands influence the electronic structure of the metal nitrene, the dynamic/fluxional behavior of reactive intermediates in solution and promotion of non-covalent interactions between substrate/catalyst to influence the site of the C-H functionalization event. Ultimately, this work is establishing universal design principles for the synthesis of catalysts that facilitate non-directed C-H functionalizations capable of overriding innate reactivity preferences that are extendable to other metals and other C-H oxidation reactions, particularly in an asymmetric context. Dr. Schomaker is also active in a number of STEM outreach programs to engage and educate students in her community about the importance of catalysis in solving challenges that currently face our society. She is particularly interested in increasing the representation of women in STEM disciplines to support the broader impacts of this work.