Bifunctional Catalysts for MHAT Hydrofunctionalization of Alkenes

用于烯烃 MHAT 加氢官能化的双功能催化剂

• 批准号: 2400341
• 负责人: Ryan Shenvi
• 金额: $ 57.5万
• 依托单位: The Scripps Research Institute
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-08-01 至 2027-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2400341&HistoricalAwards=false
• 关键词: Bifunctional; Catalysts; MHAT; Hydrofunctionalization; Alkenes

With the support of the Chemical Catalysis program in the Division of Chemistry, Professor Ryan Shenvi of Scripps Research will study a new type of base metal catalysis. Chemical reactions that produce commercial products and experimental new materials can create a heavy economic and environmental burden. When these reactions are catalyzed by small quantities of precious metals (e.g. platinum, gold, iridium), these burdens can be lessened. However, obtaining and removing these precious metals can create their own environmental, economic and political problems. This research seeks to replace precious metal catalysts with earth abundant metal catalysts such as iron. Through this work, old chemical reactions and existing materials can be made with fewer negative impacts. In addition, these catalysts enable new chemical reactions and novel materials that are unavailable to precious metals. Through these efforts, a diverse body of graduate students will be trained to enter the science and technology workforce. Chemical outreach activities from the Shenvi group to community schools are planned to engage the next generation of science and technical professionals.Alkene cross-coupling traditionally involves precious metal complexes that undergo sequential two- electron, inner-sphere reactions. These pathways involve sequential activations of substrate in which the metal center bonds covalently to intermediates: oxidative addition, coordination, migratory insertion, β- hydride elimination, decomplexation. Each of these steps can restrict the substrate scope, especially the alkene coordination step, whose rate decreases with increased alkene substitution due to steric repulsion. A lesser studied alkene reaction pathway involves metal hydride hydrogen atom transfer (MHAT), a subset of proton-coupled electron transfer (PCET). This outer-sphere elementary step generates a carbon- centered radical directly from an alkene without the need for redox-active auxiliaries or trialkyltin hydrides. In contrast to inner-sphere, coordinative metal-hydride reactions that decelerate with increasing alkene substitution, MHAT reactions can occur at high rates on tetrasubstituted alkenes or amidst steric crowding, even in dilute aqueous buffer among tertiary amines and biomolecules like DNA. The proposed research will study and expand a novel class of MHAT-based alkene functionalization reactions in which a base metal catalyst mediates bond formation at each olefinic carbon without any intermediate metal-carbon bond formation. Problems at the intersection of reactive intermediate chemistry, complex molecule synthesis and ligand design will be addressed through this work. New bioactive materials, chemical reactions and catalyst insights are expected to result from this research into catalysis.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在化学系化学催化计划的支持下，斯克里普斯研究所的Ryan Shenvi教授将研究一种新型的贱金属催化。生产商业产品和实验性新材料的化学反应可能造成沉重的经济和环境负担。当这些反应被少量的贵金属（例如铂、金、铱）催化时，这些负担可以减轻。然而，获取和移除这些贵金属可能会产生其自身的环境，经济和政治问题。这项研究试图用地球丰富的金属催化剂如铁来取代贵金属催化剂。通过这项工作，旧的化学反应和现有的材料可以产生更少的负面影响。此外，这些催化剂能够实现新的化学反应和贵金属无法获得的新材料。通过这些努力，将培训一批多样化的研究生，使他们能够进入科学和技术工作队伍。 从Shenvi集团到社区学校的化学推广活动计划吸引下一代科学和技术专业人员。烯烃交叉偶联传统上涉及进行连续双电子内层反应的贵金属络合物。这些途径涉及底物的顺序活化，其中金属中心共价键合到中间体：氧化加成、配位、迁移插入、β-氢化物消除、解络合。这些步骤中的每一个都可以限制底物的范围，特别是烯烃配位步骤，由于空间排斥，其速率随着烯烃取代度的增加而降低。较少研究的烯烃反应途径涉及金属氢化物氢原子转移（MHAT），质子耦合电子转移（PCET）的一个子集。该外层基本步骤直接从烯烃产生碳中心自由基，而不需要氧化还原活性助剂或三烷基锡氧化剂。相反，内球，协调的金属氢化物反应，减速与增加烯烃取代，MHAT反应可以发生在高速率的四取代烯烃或空间拥挤，甚至在稀水性缓冲液中叔胺和生物分子如DNA。拟议的研究将研究和扩展一类新的基于MHAT的烯烃官能化反应，其中贱金属催化剂介导每个烯烃碳的键形成，而没有任何中间金属-碳键形成。在反应中间体化学，复杂的分子合成和配体设计的交叉问题将通过这项工作得到解决。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。