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“中离子卡宾”促进的新过程。“这些化学物质是容易获得的有机化合物，有可能催化目前使用昂贵，有毒和稀有的过渡金属催化剂进行的相同类型的转化。此外，正在探索的过程有能力将生物质中发现的简单化合物转化为对科学，工程和商业重要的复杂分子。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的原料中生产增值材料。资助项目的更广泛的影响延伸到从UCSD和法国国家科学研究中心（CNRS）之间的国际交流计划中为未来的STEM劳动力带来的好处。UCSD和CNRS之间的本科生和研究生交流-联合大学使这些年轻的科学家能够发展对化学生产和化学工业所面临的挑战的国际视野，因为它过渡到提供更环保的制造方法。资助研究的目的是通过探索概念上新的和欠发达的催化领域，在基础水平上推进催化领域底物活化的方法。通过涉及Breslow中间体（BI）的单电子转移途径的NHC催化反应的例子很少，并且此类过程的合成应用受到来自经典NHC的BI的适度亲核性和还原电位的限制。与此形成鲜明对比的是，在Bertrand实验室发现的中离子卡宾是强亲核的，并且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中离子卡宾的独特属性，将NHC氧化有机催化扩展到亲电性较低的底物（如甲醛）和氧化剂较少的化合物（如芳基和乙烯基卤化物）。预期的是，感兴趣的转化将在分子间和分子内的模式和广泛的有用的产品，包括碳环和杂环，将是accessibily.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.