Mechanistic Studies Directed Toward Universal Ligands and Catalytic Reactions of Samarium Diiodide

化学结构、动力学和机制B计划支持利哈伊大学的罗伯特·A·弗劳尔斯教授对二碘化钐(SmI2)的化学进行机械研究。SmI2是有机合成中的一种重要试剂，因为它在许多重要的有机合成反应中起着重要的调节作用，包括还原、还原偶联和级联反应。SMI 2的一个重要特征是添加助溶剂或添加剂可用于控制反应的化学选择性和非对映选择性。这项工作有两个科学目标。第一个目标是开展机理研究，确定溶剂、质子供体和配位或螯合添加剂对Sm(II)试剂的亲和力的影响。这些变量与Sm(II)的反应性之间的关系将被应用于开发使用现成、廉价和无毒的添加剂来减少Sm(II)的官能团的替代方法。这项工作的第二个目标将集中在机理研究上，旨在检查已知的基于SmI2的催化体系，并利用从这些研究中收集的信息来帮助开发使用SmI2和其他基于Sm(II)的还原剂的催化反应。许多通过电子转移进行的有机反应的高度复杂性是基于我们对阴离子、阳离子、自由基和相关自由基离子的机理理解。化学家通过使用金属基氧化剂和还原剂使这些中间体相互转化的能力导致了反应的发展，这些反应利用一个或多个活性中间体在成键事件中合成具有重要社会意义的复杂分子。最广泛使用的单电子还原剂是SmI2，但添加剂在这些反应中的作用尚不清楚。在该项目框架内进行的实验旨在从机理上了解基于Sm(II)的化学和添加剂的作用，这些添加剂可以外推并应用于一系列重要和有用的过程，包括催化反应的发展。使用这种以机制为中心的方法的研究可能会比演示单一的综合应用程序为科学界提供更长期的好处。

The Chemical Structure, Dynamics and Mechanisms B Program supports Professor Robert A. Flowers of Lehigh University to carry out mechanistic studies on the chemistry of samarium diiodide (SmI2). SmI2 is an important reagent in organic synthesis due to its versatility in mediating numerous, fundamentally important reactions in organic synthesis including reductions, reductive couplings, and cascade reactions. One of the important features of SmI2 is that the addition of cosolvents or additives can be used to control the chemo- and diastereoselectivity of reactions. There are two scientific objectives of this work. The first objective is to carry out mechanistic studies that define the impact of the affinity of solvents, proton donors, and coordinating or chelating additives for Sm(II) reagents. The relationship between these variables and the reactivity of Sm(II) will be applied to the development of alternative approaches for the reduction of functional groups by SmI2 using readily available, inexpensive, and non-toxic additives. The second objective of this work will focus on mechanistic studies designed to examine known SmI2-based catalytic systems and employ the information gleaned from these studies to aid in the development of catalytic reactions employing SmI2 and other Sm(II)-based reductants.The high degree of sophistication of many organic reactions that proceed through the transfer of electrons is based on our mechanistic understanding of anions, cations, radicals, and related radical ions. The ability of chemists to interconvert these intermediates through the use of metal-based oxidants and reductants has led to the development of reactions that utilize one or more reactive intermediates in bond-forming events to synthesize complex molecules of great societal importance. The most widely used single electron reductant is SmI2, but the roles of additives in these reactions are not well understood. The experiments carried out within the framework of this project are designed to provide a mechanistic understanding of Sm(II)-based chemistry and the role of additives that can be extrapolated and applied to a range of important and useful processes including the development of catalytic reactions. Studies utilizing this mechanism-centered approach are likely to provide longer-term benefits to the scientific community than the demonstration of a single synthetic application.