Catalytic Platforms Using Aromatic Ions and Other Charged Species

项目摘要。化学催化长期以来一直是推进生物医学研究的强大力量， 使生物学上重要的分子的建设不断增加的速度，效率， 多才多艺。催化领域进步的最有力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进 通过开发利用稳定但带电的新型催化平台， 物种作为其分子解剖学的关键部分。特别地，我们已经采用芳香族离子，例如 环丙烯鎓离子和环丙烯鎓阴离子用于设计几种高效催化剂平台。 例如，我们引入了环丙烯亚胺作为一类新的强中性超碱，我们有 开发了许多手性环丙烯亚胺，已被证明是非常有效的对映选择性 布朗斯台德碱催化转化。展望未来，这一领域的主要挑战是发展 能够与酸度越来越低的底物结合同时仍保持控制的催化剂 立体选择性。因此，我们将继续努力，从根本上开发新的Brennsted基地。 这些平台将应对这一挑战。我们介绍的芳香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布朗斯台德酸催化平台。 这些催化剂是强酸性的，并且易于制备和多样化，这与许多催化剂相反。 已建立的手性布朗斯台德酸平台。在这一领域，最大的挑战在于学习如何 产生和控制越来越不稳定的碳阳离子中间体的选择性。解决这个 挑战将需要催化剂是强酸性的，手性的，并且制备简单，标准是非常好的 PCCP平台的满意度。这些和其他的研究将离子结构用于催化， 继续作为促进化学合成的刺激因素。

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.