Proton-coupled electron-transfer in Sm(II)-proton donor reactions

Sm(II)-质子供体反应中的质子耦合电子转移

• 批准号: 1565741
• 负责人: Robert Flowers
• 金额: $ 42万
• 依托单位: Lehigh University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1565741&HistoricalAwards=false
• 关键词: Proton; coupled; electron; transfer; Sm

The Chemical Structure, Dynamics, and Mechanism Program of the NSF Chemistry Division supports the research of Professor Robert Flowers in the Department of Chemistry at Lehigh University. Professor Flowers and his students are examining the mechanism for reactions of samarium (II) iodide (SmI2), a widely used reagent in organic synthesis. The first goal of this project is designed to examine the role of proton donors (alcohols and water) on the reactivity and efficiency of reactions and determine whether electrons and protons are transferred in sequential steps, or whether the process is concerted and occurs through a formal hydrogen atom transfer. The second goal of this project is to use the mechanistic information from studies on SmI2-proton donor systems to develop catalytic reactions. Students at the undergraduate and graduate level receive training in a range of scientific techniques. Outreach to elementary students leads to sustained engagement with the local community. Finally, video recordings of experimental protocols developed during these studies are freely disseminated on the Flowers research group webpage to assist scientists who use reagents based on SmI2. SmI2 is among the most widely employed reagents that reduce substrates and reactive intermediates through single electron transfer. Although most reactions of SmI2 require proton donors, the mechanism of this reagent combination is not fully understood and the current view is that reductions and reductive coupling reactions proceed through a sequential electron-transfer, proton-transfer processes. This work tests the hypothesis that reductions and reductive coupling reactions proceed through a formal hydrogen atom transfer and that the coupled transfer of an electron and proton is responsible for the unique reactivity of Sm(II)-coordinating proton donor reductions of substrates which are typically recalcitrant to reduction through single electron transfer. As mechanistic work on Sm(II)-proton donors systems is performed, data obtained from these studies is used for the development of useful and user-friendly catalytic reactions; a longstanding, but elusive goal in this field. Integration of a range of experimental techniques along with synthetic applications of proton-coupled, electron-transfer in synthesis provides a dynamic intellectual environment for students at all levels of study. The educational plan includes long-term engagement with local elementary schools designed to nurture greater interest in science. Finally, as research is published in peer-reviewed journals, video recordings of all experimental protocols are made to aid scientists who want to repeat the reaction protocols.

NSF化学部的化学结构、动力学和机制项目支持利哈伊大学化学系罗伯特·弗劳尔斯教授的研究。 弗劳尔斯教授和他的学生正在研究碘化钐（II）（SmI 2）的反应机理，这是一种广泛用于有机合成的试剂。 该项目的第一个目标是研究质子供体（醇和水）对反应活性和效率的作用，并确定电子和质子是否按顺序转移，或者该过程是否协调一致并通过正式的氢原子转移发生。 该项目的第二个目标是利用从研究SmI 2-质子供体系统的机理信息来开发催化反应。本科生和研究生一级的学生接受一系列科学技术的培训。 对小学生的外联导致与当地社区的持续接触。 最后，在这些研究期间开发的实验方案的视频记录在Flowers研究小组网页上免费传播，以帮助使用基于SmI 2的试剂的科学家。 SmI 2是最广泛使用的通过单电子转移还原底物和反应中间体的试剂之一。 虽然大多数SmI 2的反应需要质子供体，但这种试剂组合的机制尚未完全了解，目前的观点是还原和还原偶联反应通过顺序的电子转移，质子转移过程进行。 这项工作测试的假设，减少和还原偶联反应进行通过一个正式的氢原子转移和电子和质子的耦合转移是负责独特的反应性Sm（II）-配位质子供体还原的基板，这是典型的通过单电子转移的还原。 作为Sm（II）-质子供体系统的机械工作进行，从这些研究中获得的数据用于开发有用的和用户友好的催化反应，在这一领域的一个长期存在的，但难以捉摸的目标。 一系列实验技术的集成沿着与质子耦合，电子转移在合成中的合成应用提供了一个动态的智力环境，为学生在各级学习。该教育计划包括与当地小学的长期合作，旨在培养对科学的更大兴趣。 最后，随着研究成果发表在同行评议的期刊上，所有实验方案的视频记录都被制作出来，以帮助那些想要重复反应方案的科学家。