Electrophilic Attack on Coordinated Ligands Involved in Catalysis by Organometallic Complexes

Jack Norton博士，哥伦比亚大学化学系，受到化学系无机、生物无机和有机金属化学项目的支持，从事有机金属催化的机理研究，涉及对配体的亲电攻击。具体目标包括：(1)通过离子机制开发一种有效的C=N不对称加氢催化剂；(2)解释了配位叔胺（C=N加氢的产物）与相应的游离胺交换的速度比它们解离的速度快；(3)开发了一种有效的催化剂，用于氮嘧啶和环氧化物加氢生成直链胺和醇；(4)测量与正电金属配位的亚胺、醛和酮对映体相互转化的障碍；(5)确定附加配体与“约束几何”锆氮嘧啶的结合是否比与锆新世体系的结合更强。与(2)相联系，电子转移引发异常快速叔胺交换的假设将被检验。结合(3)，检验氢化物转移的区域化学取决于它是一步发生还是两步发生（即电子转移和氢原子转移是同时发生还是连续发生）的假设。本项目涉及对无机化学和有机合成具有广泛重要意义的问题。该项目将开发新的催化方法，用于制备在药物化学等领域具有重要意义的物质。此外，它将揭示目前催化剂如何运作的细节。该项目的另一个重要目标是为工业和学术职位培养本科生、研究生和博士后。由于PI的小组与G. Erker教授（德国明斯特）的小组定期交换学生，因此该项目也有一个国际组成部分。

Dr. Jack Norton, Department of Chemistry, Columbia University, is supported by the Inorganic, Bioinorganic, and Organometallic Chemistry Program of the Chemistry Division for mechanistic studies into organometallic catalysis that involves electrophilic attack on coordinated ligands. Specific objectives include: (1) developing an effective catalyst for asymmetric C=N hydrogenation by an ionic mechanism; (2) explaining how coordinated tertiary amines (the products of C=N hydrogenation) can exchange with the corresponding free amines more rapidly than they dissociate; (3) developing an effective catalyst for the hydrogenation of aziridines and epoxides to straight-chain amines and alcohols; (4) measuring the barriers to enantiomer interconversion for imines, aldehydes, and ketones that are coordinated to electropositive metals; (5) determining if the binding of additional ligands to "constrained geometry" zirconaaziridines is stronger than to zirconocene systems. In connection with (2), a hypothesis that electron transfer initiates anomalously fast tertiary amine exchanges will be tested. In connection with (3), a hypothesis that the regiochemistry of hydride transfer depends upon whether it happens in one-step or in two (i.e., whether electron transfer and hydrogen atom transfer happen simultaneously or consecutively) will be tested.This project addresses issues that have broad important to inorganic chemistry and to organic synthesis. The project will develop new catalytic methodologies for the preparation of species that are important in, e.g., pharmaceutical chemistry. In addition, it will uncover details of how present catalysts operate. Another important goal of the project is the training of undergraduate, graduate, and postdoctoral students for industrial and academic positions. There is also an international component to the project because of a regular interchange of students between the PI's group and that of Prof. G. Erker (Muenster Germany).