Enantioselective Pd-Catalyzed Reactions Enabled by Imidazole-based Chiral Biaryl Ligands

在化学系化学合成项目的支持下，佛罗里达大学的亚伦·阿波尼克教授将研究钯催化的新反应，旨在改善用于农业、清洁能源技术和人类健康的化合物的制造。这项研究的一个突出特点是，它将使产品能够以所谓的“光学活性形式”产生，在这种形式下，分子的一种“对映体构型”(大约相当于左旋的概念)占主导地位。该项目的更广泛影响将延伸到为学生提供动手培训，为他们为现代劳动力做好准备。此外，科学、技术、工程和数学(STEM)方面的公众宣传将通过名为“购物中心化学日，分子狂热”的教育活动来实现。这项活动在儿童中很受欢迎，总体上促进了与公众的互动。许多具有不同社会经济背景的参观者参加了会议。长期以来，钯催化的烯烃反应一直被认为是制备原料和精细化学品的极好起点。许多这样的转化涉及到核配位反应；然而，反应参数的细微变化影响了反应机理，使得设计可靠的对映选择性过程变得困难。该项目通过利用Pd(II)·StackPhos络合物在对映选择性内-1，2-烯烃双官能化反应中的应用，专门解决了碳官能化方面的挑战。在这里，催化剂通过识别特定的烯烃pi面来控制产物的立体化学构型，导致净的对映选择性烯烃功能化反应。这项研究的一个关键目标是确定对合成反应和反加成反应都表现出高水平立体选择性的催化剂。将使用机械探测器来收集关于添加模式的信息。进一步的研究目标是碳环的形成反应，主要是通过内模环化和补充现有的更发达的外模环化反应。更多的工作将扩展到迄今为止所研究的各种转化，以涵盖也可能导致有用的对映体富集化产品的替代底物。通过对对映选择性内-1，2-二官能化反应所需因素的基本了解，成功地实现该项目的目标将对过渡金属催化领域产生重大影响。预计这一发现将使这一战略在学术和工业实验室的一系列综合应用程序中得到广泛部署。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With support of the Chemical Synthesis program in the Division of Chemistry, Professor Aaron Aponick of the University of Florida will study new palladium-catalyzed reactions designed to improve the manufacture of chemical compounds used in agriculture, clean energy technologies, and human health. A prominent feature of the research is that it will enable the generation of products in a so-called 'optically active form' in which one 'enantiomeric configuration' (approximately equivalent to the concept of handedness) of the molecule predominates. The broader impacts of the project will extend to providing hands-on training for students, preparing them for the modern workforce. In addition, public outreach in science, technology, engineering, and mathematics (STEM) will be achieved through an educational event called "Chemistry Day at the Mall, Molecular Mania." This event is popular with children and fosters interactions with the public, in general. Many visitors with diverse socioeconomic backgrounds participate.Palladium-catalyzed reactions of olefins have long been recognized as excellent starting points for the preparation of feedstock and fine chemicals. Many such transformations involve a nucleopalladation reaction; however, subtle changes in reaction parameters impact reaction mechanism making it difficult to design reliable enantioselective processes. The funded project specifically addresses challenges in carbofunctionalization by the utilization of Pd(II)•StackPhos complexes in enantioselective endo-1,2-alkene difunctionalization reactions. Herein, the catalyst controls the stereochemical configuration of products by recognizing a specific olefin pi-face, leading to net enantioselective olefin functionalization reactions. A key goal of the research is to identify catalysts that exhibit high levels of stereoselectivity for both syn- and anti-addition reactions. Mechanistic probes will be used to glean information in regard to the mode of addition. Further studies are aimed at carbocycle-forming reactions, primarily through the endo-mode cyclization and complementing the more highly developed exo-mode cyclizations currently available. Additional work will expand on the kinds of transformations hitherto investigated to encompass alternative substrates that may also lead to useful enantioenriched products. Successful realization of the goals of the funded project will have a significant impact on the field of transition metal-mediated catalysis by providing a fundamental understanding of the factors necessary for enantioselective endo-1,2-difunctionalization reactions. It is anticipated that the findings will enable widespread deployment of this strategy across a range of synthetic applications in both academic and industrial laboratories.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.