Reactive Intermediates in Gold(I) Catalysis

杜克大学化学系的Ross a . Widenhoefer教授在化学结构、动力学和机制B项目资助下，研究了金催化化学反应的机制，特别是那些二价碳原子转移到碳碳双键形成环丙烷的化学反应。这是一个日益重要的综合转变。研究包括实验以确定金催化过程的范围和机制以及金配合物的结构。这项研究提供了机械洞察力，将服务于不断增长的全球研究人员社区，致力于开发新的和更有效的金(I)催化转化。研究活动已完全纳入研究生和本科生研究人员的科学教育和培训，包括来自传统上在科学领域代表性不足的群体的学生。研究生通过参加杜克大学研究生院提供的教育活动来增加他们的研究经验。研究生还与杜克核磁共振（NMR）中心的Ben Bobay博士合作参加社区外展活动，为当地高中生提供现代高场核磁共振波谱的实践机会，并在核磁共振数据的处理和解释方面进行一对一的指导。本课题研究了金类碳络合物和阳离子金类碳络合物的结构和反应性，包括与金到烯烃碳转移（环丙烷化）、金-氧碳络合物和类碳络合物以及阳离子- γ -不饱和金碳络合物有关的结构和反应性。尽管在这一领域的工作越来越多，但关于涉及这些金配合物的机制的实验信息有限。研究活动填补了这一领域的重要空白，并发展了对通过稳定重氮化合物的碳转移或通过在金存在下的烯烃氧化产生的配合物性质的实验基础理解。主要研究方向有三个：(1)通过建立碳转移过渡态模型来阐明金到烯烃的转移机理；金金属环丁烷配合物的独立合成；化学计量条件下金到烯烃的转移动力学分析；(2)通过研究金配合物与稳定的N-和s -酰类化合物的反应，以及吡啶N-氧化物与阳离子金配合物的反应，评价了阳离子金-氧羰基和类羰基配合物的性质和反应性；(3)通过阳离子金烯丙烯和乙烯基卡宾配合物的合成和表征，探讨了不饱和金卡宾配合物的结构和反应性。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 project funded by the Chemical Structure, Dynamics and Mechanisms B Program of the Chemistry Division, Professor Ross A. Widenhoefer in the Department of Chemistry at Duke University investigates the mechanisms of gold-catalyzed chemical reactions, especially those in which a divalent carbon atom is transferred to a carbon-carbon double bond to form a cyclopropane. This is a synthetic transformation of growing importance. Studies include experiments to determine the scope and mechanisms of gold-catalyzed processes and the structure of gold complexes. This research provides mechanistic insight that will serve the ever growing global community of researchers working toward the development of new and more efficient gold(I) catalyzed transformations. Research activities are fully integrated into the scientific education and training of graduate and undergraduate student researchers, including students from groups traditionally underrepresented in the sciences. Graduate students augment their research experience through participation in educational activities offered through the Duke University Graduate School. Graduate students also participate in community outreach activities in collaboration with Dr. Ben Bobay of the Duke Nuclear Magnetic Resonance (NMR) center which provide local high school students with hands-on exposure to modern high-field NMR spectroscopy and one-on-one instruction in the processing and interpretation of NMR data. This project investigates the structure and reactivity of gold carbenoid complexes and cationic gold carbene complexes, including those relevant to gold-to-alkene carbene transfer (cyclopropanation), gold alpha-oxo carbene and carbenoid complexes, and cationic beta, gamma-unsaturated gold carbene complexes. Despite a growing body of work in this area, limited experimental information is available regarding mechanisms which involve these gold complexes. Research activities fill important gaps in this field and develop an experimentally-grounded understanding of the nature of the complexes generated either through carbene transfer from stabilized diazo compounds or through the oxidation of alkenes in the presence of gold. The research addresses three main areas of inquiry: (1) elucidation of the mechanisms of gold to alkene carbene transfer by modeling the transition state for carbene transfer, independent synthesis of gold metallacyclobutane complexes, and kinetic analysis of gold to alkene carbene transfer under stoichiometric conditions; (2) evaluation of the nature and reactivity of cationic gold alpha-oxo carbene and carbenoid complexes by studying the reactions of gold complexes with stabilized N- and S-ylides and the reactions of pyridine N-oxides and with cationic gold complexes; and (3) interrogation of the structure and reactivity of unsaturated gold carbene complexes through the synthesis and characterization of cationic gold allenylidene and vinyl carbene complexes.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.