Catalytic Platforms Using Aromatic Ions and Other Charged Species

项目摘要。长期以来，化学催化一直是推动生物医学研究的一股强大力量 使构建具有生物重要性的分子的速度、效率和 多功能性。在催化领域取得进展的最强大的驱动力之一是发现了 新的催化平台和概念。拟议的研究计划主要集中在推动 通过开发利用稳定但带电的新型催化平台来实现催化领域 物种作为其分子解剖学的关键部分。特别是，我们使用了芳香族离子，如 针对环丙烯离子和环戊二烯基阴离子设计了几个高效的催化剂平台。 例如，我们引入了环丙烯亚胺作为一种新的强中性超碱，我们有 开发了许多手性环丙烯亚胺类化合物，已被证明是高效的对映体选择性 Brnsted碱催化的转化反应。展望未来，这一领域的主要挑战是发展 催化剂能够与酸度越来越低的底物结合，同时仍保持控制 过度的立体选择性。因此，我们的持续努力旨在从根本上开发新的布伦斯特德基地 将应对这一挑战的平台。我们已经介绍的芳香族离子的第二个主要应用 五羧基环戊二烯(PCCPs)是一种新型的对映体选择性Brnsted酸催化平台。 这些催化剂具有很强的酸性，易于制备和多样化，这与许多催化剂形成了鲜明的对比。 已建立的手性Brnsted酸平台。在这一领域，首要挑战在于学习如何 产生和控制日益不稳定的碳阳离子中间体的选择性。解决这个问题 挑战将需要强酸性、手性和微不足道的催化剂来制备，标准是非常好的 得到了PCCP平台的满意。这些和其他关于使用离子结构进行催化的研究将 继续作为化学合成进步的推动力。

Project Summary. Chemical catalysis has long been a potent force for advancing biomedical research by enabling the construction of biologically important molecules with ever-increasing speed, efficiency, and versatility. One of the most potent driving forces for progress in the area of catalysis has been the discovery of new catalytic platforms and concepts. The proposed research program is broadly focused on advancing the area of catalysis through the development of novel catalytic platforms that utilize stable but electrically charged species as a key part of their molecular anatomy. In particular, we have employed aromatic ions such as cyclopropenium ion and cyclopentadienyl anion for the design of several highly effective catalyst platforms. For example, we introduced cyclopropenimines as a new class of strong, neutral superbase, and we have developed a number of chiral cyclopropenimines that have proven to be highly effective for enantioselective BrØnsted base catalyzed transformations. Moving forward, the major challenge in this area is to develop catalysts that are capable of engaging substrates of increasingly lower acidity while still maintaining control over stereoselectivity. Our continuing efforts are thus aimed at developing fundamentally new BrØnsted base platforms that will address this challenge. A second major application of aromatic ions that we have introduced is the pentacarboxycyclopentadienes (PCCPs) as a new platform for enantioselective BrØnsted acid catalysis. These catalysts are strongly acidic and are simple to prepare and to diversify, which stands in contrast to many of the established chiral BrØnsted acid platforms. In this area, the forefront challenge lies in learning how to generate and control the selectivity of increasingly unstabilized carbocation intermediates. Solving this challenge will require catalysts that are strongly acidic, chiral, and trivial to prepare, criteria which are very well satisfied by the PCCP platform. These and other investigations into the use of ionic structures to catalysis will continue to serve as a stimulus for advancements in chemical synthesis.