CAS: Catalytic Synthesis via Small Molecule Evolution

在化学系化学合成项目的支持下，堪萨斯大学的Jon Tunge教授正在研究开发利用分子中固有能量的战略，以实现高效和环境可持续的化学制造工艺。具体而言，从简单原料中释放小的稳定分子（二氧化碳和/或氢），有时与收集光能结合，将提供驱动化学反应的能量，而不需要传统的、更浪费的能量输入方法。为了进一步减少化学对环境的影响，同时也允许开发新型的反应途径，基于钴的催化剂，地球丰富的金属，而不是传统的更昂贵和稀有的贵金属，将被用作关键的促进剂。预计所开发的方法将适用于合成各种各样的材料，这些材料具有作为药剂、农用化学品和其他对科学、工程和商业有价值的物质的潜在应用。资助项目的更广泛的影响延伸到累积到社会的好处，因为教授Tunge和他的同事从事推广和教育活动，旨在将本研究的目标与培训和招聘计划，包括促进“绿色化学”的原则。这些活动的一个重要目标将是吸引来自不同背景的学生，包括属于科学，技术，工程和数学（STEM）领域代表性不足的群体的个人，以应对可持续化学的当代挑战。资助项目的重点是基于通过裂解C-C和C-H键催化生成活性中间体的化学转化的发展。正在开发的催化途径利用脱羧反应提供了一种有效的策略，用于直接从廉价的羧酸原位形成合成有用的反应性中间体。正在研究的其他工艺利用析氢反应（HER）进行原子经济性官能化。钴催化剂在脱羧偶联反应中取代了传统的昂贵的钯催化剂，并有望实现使用现有技术无法实现的新的转化类型。此外，光氧化还原催化的析氢将允许氨基酸和肽的位点特异性官能化，同时还实现区域控制的脱羧Heck样酰化。这些研究将为合成化学家提供一个通用的范例，用于在温和的条件下获得活性物质，同时使用以下方法产生最少的废物：（1）用于过渡金属催化剂的氧化还原改组的可见光氧化还原催化剂，和（2）通过释放最小分子而允许氧化偶联的析氢，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。

With the support of the Chemical Synthesis Program in the Division of Chemistry, Professor Jon Tunge of the University of Kansas is studying the development of strategies that harness the inherent energy in molecules to enable efficient and environmentally sustainable processes for chemical manufacturing. Specifically, the release of small stable molecules (carbon dioxide and/or hydrogen) from simple feedstocks, sometimes in combination with harvesting light energy, will provide the energy to drive chemical reactions without the need for traditional, more wasteful, methods of energy input. To further lessen the environmental impact of the chemistry while also allowing for the exploitation of new types of reaction pathways, catalysts based on cobalt, an earth abundant metal, rather than traditional more expensive and rare precious metals, will be employed as critical promoters. It is anticipated that the methods developed will be applicable to the synthesis of a wide variety of materials with potential applications as pharmaceutical agents, agrochemicals, and other substances of value to science, engineering, and commerce. The broader impacts of the funded project extend to the benefits accrued to society as Professor Tunge and his coworkers engage in outreach and educational activities designed to integrate the goals of this research with training and recruitment programs that incorporate the promotion of 'green chemistry' principles. A significant goal of these activities will be to attract students from diverse backgrounds, including individuals belonging to groups underrepresented in science, technology, engineering, and mathematics (STEM) fields, to address contemporary challenges in sustainable chemistry.The funded project is focused on the development of chemical transformations based on the catalytic generation of reactive intermediates via the cleavage of C–C and C–H bonds. The catalytic pathways being developed utilize decarboxylation to provide an efficient strategy for the in situ formation of synthetically useful reactive intermediates directly from inexpensive carboxylic acids. Other processes under investigation utilize the hydrogen evolution reaction (HER) for atom-economical functionalization. Cobalt catalysts replace traditional, expensive, palladium catalysts in decarboxylative coupling reactions and are anticipated to allow for new transformation types that are inaccessible using current technologies. Additionally, photoredox-catalyzed hydrogen evolution will allow for the site-specific functionalization of amino acids and peptides, while also enabling regiocontrolled decarboxylative Heck-like acylations. These studies will advance a general paradigm for synthetic chemists to use for accessing reactive species under mild conditions, while generating minimal waste using: (1) visible light photoredox catalysts for redox shuffling of transition metal catalysts, and (2) hydrogen evolution to allow oxidative couplings through liberation of the smallest molecule, hydrogen.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.