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CAREER: Metal-Free C-C Bond Formation and C-O Bond Cleavage Mediated by Electron-Donor-Acceptor Complexes of Arenes

事业：芳烃电子供体-受体配合物介导的无金属 C-C 键形成和 C-O 键断裂

基本信息

批准号：
2239235
负责人：
Sebastien Laulhe
金额：
$ 77万
依托单位：
Indiana University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2023
资助国家：
美国
起止时间：
2023-04-01 至 2028-03-31
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2239235&HistoricalAwards=false
关键词：
CAREER Metal Free Bond Formation

项目摘要

With the support of the Chemical Synthesis Program in the Division of Chemistry, Sébastien Laulhé of Indiana University-Purdue University Indianapolis is studying new heavy metal-free processes designed to reduce the environmental footprint of chemical manufacturing. Blue light is employed to activate so-called 'electron-donor-acceptor complexes' enabling them to either mediate the assembly of carbon-carbon bonds or else to break carbon-oxygen bonds. Processes belonging to the first class are useful for the generation of pharmaceutical agents, agrochemicals, and other societally important products, and the approach being pursued may provide an alternative to current technologies reliant on the use of rare and/or toxic metal species. The second type of processes will be deployed to break down biomass-derived molecules, such as lignin, to turn what are typically regarded as agricultural waste streams into renewable and valuable sources of carbon, thereby potentially reducing dependence on fossil-based carbon sources. The broader impacts of the award extend to the benefits accrued to society as Dr. Laulhé and his team of coworkers pursue a range of activities, including the provision of stimulating and educational research experiences, to better prepare undergraduate students for careers in the STEM (science, technology, engineering and mathematics) workforce. The funding secured will also enable Dr. Laulhé to continue to develop an organic chemistry curriculum for visually impaired students, the results of these efforts will be shared with the higher education community.The formation of carbon-carbon bonds through regioselective C(sp3)–H functionalization strategies in the absence of transition-metals remains a challenge. The research being pursued under this project will address this problem by utilizing aryl radical species capable of effecting hydrogen-atom transfer that are released upon visible light-mediated excitation of electron-donor-acceptor (EDA) complexes of readily generated carbanions (e.g., aminoacetate enolates) and haloarenes. A major goal of the research is to apply this principle to access non-canonical amino acid derivatives via site-selective direct C-H functionalization and to render such transformations diastereoselective by manipulation of the transition state for the radical-radical coupling step using specific counter ions and/or the use of chiral organocatalysts. The second part of the funded project will exploit EDA complexes of solvent anions (e.g., dimsyl anion) and arene-containing ethers to promote selective C–O bond cleavages upon irradiation with visible light. In this case, it is expected that tuning of the electronic parameters between electron-donors and electron-acceptors will enable selective debenzylation of complex protected alcohols and depolymerization of lignocellulosic biomass. A number of significant (and heavy metal-free) new methods for both the functionalization of C–H bonds and the cleavage of C–O bonds, are likely emerge from this research program and the pursuit of the aims described will further fundamental knowledge of EDA complex photochemistry.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.

在化学系化学合成项目的支持下，印第安纳大学-普渡大学印第安纳波利斯分校的ssambastien laulh<e:1>正在研究新的无重金属工艺，旨在减少化学生产的环境足迹。蓝光被用来激活所谓的“电子-供体-受体复合物”，使它们能够介导碳-碳键的组装，或者破坏碳-氧键。属于第一类的工艺对于生产药剂、农用化学品和其他具有重要社会意义的产品是有用的，正在采用的方法可能为依赖使用稀有和/或有毒金属的现有技术提供一种替代方法。第二类过程将用于分解生物质衍生分子，如木质素，将通常被视为农业废物流转化为可再生和有价值的碳源，从而有可能减少对化石碳源的依赖。laulh<s:1>博士和他的同事团队开展了一系列活动，包括提供激励性和教育性的研究经验，以更好地为本科生在STEM（科学、技术、工程和数学）的职业生涯做好准备，因此，该奖项的广泛影响延伸到社会所带来的利益。获得的资助也将使劳赫博士能够继续为视障学生开发有机化学课程，这些努力的成果将与高等教育界分享。在没有过渡金属的情况下，通过区域选择性C(sp3) -H功能化策略形成碳-碳键仍然是一个挑战。该项目正在进行的研究将通过利用能够影响氢原子转移的芳基自由基来解决这个问题，这些自由基是在可见光介导的容易产生的碳离子（例如，氨基乙酸烯醇酯）和卤代芳烃的电子供体-受体（EDA）复合物的激发下释放的。该研究的一个主要目标是将这一原理应用于通过位点选择性直接C-H功能化来获得非规范氨基酸衍生物，并通过使用特定的反离子和/或使用手性有机催化剂来操纵自由基-自由基偶联步骤的过渡态，从而使这种转化具有非对映选择性。该资助项目的第二部分将利用溶剂阴离子（如二烷基阴离子）和含芳烃醚的EDA配合物，在可见光照射下促进C-O键的选择性裂解。在这种情况下，预计电子给体和电子受体之间的电子参数的调整将使复合保护醇的选择性去苄化和木质纤维素生物质的解聚成为可能。许多重要的（和无重金属的）C-H键功能化和C-O键裂解的新方法可能会从这个研究项目中出现，所描述的目标的追求将进一步了解EDA复杂光化学的基础知识。该奖项反映了美国国家科学基金会的法定使命，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。