CAREER: Mechanistic Study of Radical Initiations for Aromatic Functionalization

在这个由化学部化学结构、动力学和机理B项目资助的CAREER项目中，加州大学默塞德分校化学和化学生物系的Ryan Baxter教授正在开发通过单电子转移引发自由基反应的新策略。由于单电子反应（自由基反应）传统上被认为是高活性且难以控制的，本研究的目标是更好地了解自由基引发的基本特性，以设计温和且用户友好的实验方案。在药物、维生素、材料和聚合物中发现了许多可以通过自由基化学获得的结构，因此，自由基引发的新策略可能对许多科学领域产生积极影响，直接造福社会。该项目包括实时监测自由基反应，以了解化学行为。所得的反应数据用于开发本科有机化学实验和讲座课程的教材。此外，通过工业伙伴关系，收集和提炼了大量真实的反应数据，以建立一个本科/研究生教育材料库，供全国各地的教育工作者使用。芳烃和杂芳烃是常见的结构，具有许多理想的材料。它们需要迅速多样化的战略。自由基碳氢功能化提供了通过亲核或亲电过程直接修饰芳香碳氢键的能力，尽管不受控制的反应性在分子间过程中很常见。该项目涉及两个离散的目标，研究影响合成重要反应的自由基起始率的基本物理性质。第一个重点是开发使用银离子作为氧化剂和外源吡啶配体的催化剂系统，以一种新的方式控制杂芳烃分子间亲核功能化的自由基起始速率。催化剂的氧化还原性能通过电化学研究，这些数据与整体反应速率相关联，从而为最佳催化剂/氧化剂体系的开发提供信息。第二个目标涉及铁催化的氮氧键还原，通过亲电过程促进芳烃的分子间自由基胺化。研究了各种氮自由基前体的电子性质，以制定有效的策略，将温和的引发与可靠的引发率结合起来。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。

In this CAREER project, funded by the Chemical Structure, Dynamics & Mechanisms B Program of the Chemistry Division, Professor Ryan Baxter of the Department of Chemistry & Chemical Biology at the University of California, Merced is developing new strategies for initiating radical reactions through single-electron transfers. Because one electron reactions (radical reactions) are traditionally viewed as highly reactive and difficult to control, the goal of this research is to better understand fundamental properties of radical initiations to engineer mild and user-friendly experimental protocols. Many structures that can be accessed via radical chemistry are found in drugs, vitamins, materials and polymers, and so new strategies for radical initiation may have a positive impact on many fields of science that directly benefit society. The project involves monitoring radical reactions in real-time to understand chemical behavior. The resulting reaction data is used to develop educational materials for undergraduate organic chemistry laboratory and lecture courses. In addition, through industrial partnerships, volumes of authentic reaction data is collected and refined to develop a repository of undergraduate/graduate educational materials that are made available to educators throughout the Nation. Arenes and heteroarenes are common structures with many desirable materials. Strategies for their rapid diversification are in demand. Radical carbon-hydrogen functionalization offers the ability to directly modify aromatic carbon hydrogen bonds via either nucleophilic or electrophilic processes, although uncontrolled reactivity is common to intermolecular processes. This project involves two discrete aims to study fundamental physical properties that affect rates of radical initiation for synthetically important reactions. The first focuses on developing catalyst systems that use silver ion, as an oxidant, and exogenous pyridine ligands in a novel way to control the rates of radical initiation for intermolecular nucleophilic functionalization of heteroarenes. Catalyst redox properties are studied electrochemically, and this data is correlated with global reaction rates to inform the development of optimum catalyst/oxidant systems. The second aim involves the iron-catalyzed reduction of nitrogen-oxygen bonds to promote intermolecular radical amination of arenes through an electrophilic process. The electronic properties of various nitrogen-radical precursors are examined to develop efficient strategies that combine mild initiation with reliable rates of initiation.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.