Unleashing Mesoionic Carbene-derived Super-reductants to Overcome the Limitations of NHC- Oxidative Organocatalysis Without a Co-Catalyst

在化学系化学催化（CAT）项目的支持下，加州大学圣地亚哥分校（UCSD）的Guy Bertrand教授正在研究由所谓的“介离子碳烯”促进的新过程。这些化学物质是很容易获得的有机化合物，它们有潜力催化目前用昂贵、有毒和稀有的过渡金属基催化剂进行的相同类型的转化。此外，正在探索的过程具有将生物质中发现的简单化合物转化为对科学、工程和商业具有重要意义的复杂分子的能力。因此，预计正在探索的研究将有助于以更可持续和更经济的方式从简单原料生产增值材料。该资助项目的更广泛影响延伸到加州大学圣地亚哥分校与Bertrand教授牵头的法国国家科学研究中心（CNRS）之间的国际交流计划对未来STEM劳动力的好处。加州大学圣地亚哥分校和cnrs关联大学之间的本科生和研究生交流使这些年轻的科学家能够在化学生产和化学工业面临的挑战方面发展国际视野，因为它正在向提供更环保的制造方法过渡。资助研究的目的是通过探索概念上新的和不发达的底物活化方法，在基础水平上推进催化领域。nhc通过单电子转移途径催化涉及Breslow中间体（BIs）的反应的例子很少，并且这些过程的合成应用受到由经典NHCs衍生的BIs的中等亲核性和还原潜力的限制。与之形成鲜明对比的是，在伯特兰实验室发现的中离子碳烯具有强烈的亲核性，是迄今为止报道的最有效的有机还原剂之一。该项目的目标是利用介离子碳烯的独特属性，将NHC氧化有机催化扩展到亲电性较低的底物，如甲醛，以及较少的氧化剂，如芳基卤化物和乙烯基卤化物。预期分子间和分子内的转化都可以实现，并且可以获得包括碳环和杂环在内的各种有用的产物。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。

With the support of the Chemical Catalysis (CAT) Program in the Division of Chemistry, Professor Guy Bertrand of the University of California, San Diego (UCSD) is studying new processes promoted by so-called "mesoionic carbenes." These chemical species are readily available organic compounds that have the potential to catalyze the same kinds of transformations currently conducted with expensive, toxic, and rare transition metal-based catalysts. Furthermore, the processes being explored have the capacity to convert simple compounds found in biomass to complex molecules of importance to science, engineering, and commerce. Accordingly, it is anticipated that the research being explored will facilitate the manufacture of value-added materials from simple feed stocks in a more sustainable and economical manner. The broader impacts of the funded project extend to the benefits accrued to the future STEM workforce from an international exchange program between UCSD and the French Centre National de la Recherche Scientifique (CNRS) that Professor Bertrand spearheads. The exchange of undergraduate and graduate students between UCSD and CNRS-associated universities enables these young scientists to develop an international perspective on both chemical production and the challenges facing the chemical industry as it transitions to deliver more environmentally responsible manufacturing methods.The aim of the funded research is to advance the field of catalysis on a fundamental level through the exploration of conceptually new and underdeveloped methods of substrate activation. There are few examples of NHC-catalyzed reactions via single electron transfer pathways involving Breslow intermediates (BIs), and the synthetic applications of such processes are limited by the moderate nucleophilicity and reduction potential of BIs derived from classical NHCs. In marked contrast, mesoionic carbenes, which were discovered in the Bertrand laboratory, are strongly nucleophilic and among the most potent organic reducing agents reported to date. The goal of the project is to exploit the unique attributes of mesoionic carbenes to expand NHC oxidative organocatalysis to less electrophilic substrates such as formaldehyde, and to less oxidizing agents such as aryl- and vinyl-halides. It is anticipated that the transformations of interest will be achieveable in both inter- and intramolecular modalities and that a wide range of useful products, including carbocycles and heterocycles, will be accessible.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.