Palladium-Catalyzed Aerobic Allylic Oxidations: Mechanisms and Applications

通过这一奖项，NSF化学部门的化学催化计划支持了Shannon Stahl教授的研究，即设计能够加速化学反应(催化剂)以执行特定化学转化(用氧气氧化有机分子)的试剂。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，会产生大量不需要的副产品，和/或产生对环境有害的废物。威斯康星大学麦迪逊分校的斯塔尔教授和他的团队正在开发催化剂，这种催化剂可以用氧气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品。这些研究致力于催化剂的效率，试图使它们更持久和更具选择性。这项研究计划培养研究生和本科生成为化学劳动力的一部分，并招募代表不足的少数族裔进入STEM学科。此外，正在设计重要的安全协议来大规模地与氧和有机分子一起工作，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中的一个关键挑战，因为它能够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，这种催化剂以分子氧为末端氧化剂，介导烯丙基C-H键的选择性氧化。得到的烯丙基羧酸盐产品是许多合成有用的二次官能化反应中的多种中间体。研究工作探索了提高Pd催化剂稳定性的策略，作为实现高周转率的一种手段。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。机械学研究在这一努力中发挥着重要作用，并借助创新的机械学工具，如能够连续在线输送氧气和气体吸收动力学分析的高压核磁共振反应堆。这些基础研究侧重于实践目标的实现，以及伴随而来的重要安全协议的开发，为不同的研究生和本科生提供了一个强有力的培训环境。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.