Palladium-Catalyzed Aerobic Allylic Oxidations: Mechanisms and Applications

通过这个奖项，美国国家科学基金会化学部的化学催化项目正在支持香农·斯塔尔教授设计加速化学反应（催化剂）以执行特定化学转化（用氧氧化有机分子）的研究。氧化过程是生产商品化学品、药品和农用化学品的重要化学反应。不幸的是，化学氧化通常使用的试剂（氧化剂）是有毒的，比需要的更强大，导致大量不需要的副产品，和/或产生对环境有害的废物。斯塔尔教授和他在威斯康星大学麦迪逊分校的团队正在开发一种催化剂，可以用氧氧化被称为烯烃的化学原料；这种氧化剂只产生水作为副产物。这些研究解决了催化剂的效率，试图使它们更持久，更有选择性。该研究项目培养研究生和本科生成为化学劳动力的一部分，并招募代表性不足的少数民族进入STEM学科。此外，正在设计重要的安全协议，以大规模地处理氧气和有机分子，因此，这项研究具有重要的工业意义。C-H键的选择性氧化是化学合成和化学工业的一个关键挑战，因为它可以更有效地合成新的和已知的化学结构。斯塔尔教授和他的团队正在开发和表征钯催化剂，以分子氧作为末端氧化剂，介导烯丙基C-H键的选择性氧化。所得到的烯丙基羧酸酯产品是许多合成有用的二级官能化反应的多功能中间体。研究努力探索提高钯催化剂稳定性的策略，作为实现高周转率的手段。实现这一目标的方法包括设计新的配体和确定使催化剂具有内在热力学稳定性的反应条件。机理研究在这项工作中发挥着重要作用，在创新的机理工具的帮助下，如能够连续在线输送O2和气体摄取动力学分析的高压核磁共振反应器。这些基础研究侧重于实现实际目标，并伴随发展重要的安全协议，为不同群体的研究生和本科生提供了强大的培训环境。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With this award, the Chemical Catalysis Program of the NSF Division of Chemistry is supporting the research of Professor Shannon Stahl to design agents that speed chemical reactions (catalysts) to perform specific chemical transformations (oxidize organic molecules with oxygen). Oxidation processes are important chemical reactions for the production of commodity chemicals, pharmaceuticals, and agrochemicals. Unfortunately, chemical oxidations usually use reagents (oxidants) that are toxic, are more powerful than needed and result in a large number of unwanted by-products, and/or generate waste that is harmful to the environment. Professor Stahl and his group at the University of Wisconsin–Madison are developing catalysts that oxidize chemical feedstocks called alkenes with oxygen; this oxidant generates only water as a by-product. These studies address the efficiency of the catalysts, trying to make them longer-lasting and more selective. This research program trains graduate and undergraduate students to become part of the chemical workforce and to recruit underrepresented minorities to STEM disciplines. In addition, important safety protocols are being designed to work with oxygen and organic molecules on large scale and thus, this research has important industrial relevance.The selective oxidation of C–H bonds is a key challenge in chemical synthesis and in the chemical industry, as it enables more efficient synthesis of novel and known chemical structures. Professor Stahl and his group are developing and characterizing palladium catalysts that mediate selective oxidation of allylic C–H bonds using molecular oxygen as the terminal oxidant. The resulting allylic carboxylate products are versatile intermediates in numerous synthetically-useful, secondary functionalization reactions. Research efforts explore strategies to enhance the stability of the Pd catalysts as a means of achieving high turnover numbers. Approaches towards this goal include the design of new ligands and the identification of reaction conditions that enable the catalysts to have intrinsic thermodynamic stability. Mechanistic studies play an important role in this effort, aided by innovative mechanistic tools such as a high-pressure NMR reactor capable of continuous on-line delivery of O2 and gas-uptake kinetic analysis. These fundamental studies focused on the achievement of practical goals, and the concomitant development of important safety protocols, provides a strong training environment for a diverse group of graduate and undergraduate students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.