Electrophilic Attack on Coordinated Ligands Involved in Catalysis by Organometallic Complexes

Jack Norton博士，哥伦比亚大学化学系，由化学部无机化学、生物无机化学和金属有机化学项目支持，致力于对有机金属催化的机理研究，包括对配位配体的亲电攻击。具体目标包括：(1)开发一种通过离子机制进行不对称C=N氢化的有效催化剂；(2)解释配位叔胺(C=N加氢的产物)如何比它们解离更快地与相应的游离胺交换；(3)开发一种有效的催化剂，用于氮杂环烷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、醛和酮的对映体相互转化的势垒；(5)确定额外的配体与“受约束几何”的锆杂氮烷体系的结合是否比与茂锆系的结合更强。关于(2)，将检验电子转移启动异常快速的叔胺交换的假设。关于(3)，将检验一个假设，即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)。这个项目解决了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种。此外，它还将揭示目前催化剂如何运行的细节。该项目的另一个重要目标是为工业和学术岗位培养本科生、研究生和博士后。该项目还有一个国际组成部分，因为国际学生联合会的小组和G.Erker教授(德国明斯特)的小组定期交换学生。

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).