Reactions and Stereochemistry of Organometallic Compounds Related to Asymmetric Synthesis and Catalytic Activity

有机金属化合物常被用作一种有机化合物转化为另一种有机化合物的催化剂。不幸的是，这种转化常常导致同分异构体的混合物，即由相同原子组成的分子，但其三维结构不同。该项目涉及高度不对称有机金属化合物的合成，旨在作为更具体的催化剂来控制反应产物的三维结构。有机分子的三维结构在生物反应中尤为重要，这些有机金属化合物常用于实验室合成天然产物。将进行研究，开发利用金属配合物进行不对称和区域选择性合成的新方法，并阐明对合成有用的立体选择性反应的机制。高氧化态有机金属配合物在这些应用中的潜在效用将被探索。x射线晶体学已成为固体结构表征的常规工具。然而，许多有机金属化合物在溶液中以构象异构体的混合物重排或存在。实验结果表明，这些构象的稳定性对产物立体化学的分布起着重要作用。活性中间体和催化物质通常以较低浓度存在，不能作为固体分离。将开发一种新的方法来阐明溶液中的详细结构信息。这将涉及设计和合成含有顺磁性金属离子的配体，这些金属离子与有机金属结合。这些顺磁配体产生的各向同性位移和场对齐效应将允许详细描述溶液中的中间体和催化物质（角度和距离）。

Organometallic compounds are frequently used as catalysts for the conversion of one organic compound into another. Unfortunately, such conversions often result in mixtures of isomers, i.e., molecules comprised of the same atoms, but differing in their three-dimensional structures. This project involves the synthesis of highly unsymmetrical organometallic compounds designed to function as more specific catalysts to control the three-dimensional structures of reaction products. The three- dimensional structures of organic molecules are especially important in biological reactions, and these organometallic compounds are often used in the laboratory synthesis of natural products. Research will be undertaken to develop new methods using metal complexes for asymmetric and regioselective syntheses and to elucidate the mechanisms of stereoselective reactions which are synthetically useful. The potential utility of higher oxidation state organometallic complexes for these applications will be explored. X-ray crystallography has become a routine tool for structural characterization in solids. However, many organometallic compounds rearrange or exist as mixtures of conformational isomers in solution. It has been shown in this laboratory that the stability of these conformers plays a major role in the distribution of product stereochemistry. Reactive intermediates and catalytic species often exist in lower concentrations and cannot be isolated as solids. A new method will be developed to elucidate detailed structural information in solution. This will involve the design and synthesis of ligands containing paramagnetic metal ions which bind to organometallics. The isotropic shifts and the effects of field alignment produced by these paramagnetic ligands will allow detailed delineation (angles and distances) of intermediates and catalytic species in solution.