Chirality-Driven Self-Assembly of Dual Catalytic Dendrimers: Application Toward One-Pot Tandem Reactions

在活细胞中，许多化学转化同时发生，催化它们的酶之间没有干扰。为了实现这一目标，大自然已经进化到将催化剂位点整合到酶口袋中，或者通过膜的物理分离。成功构建此类框架的人工类似物将减少催化剂失活并消除不良副反应。这些都是催化中的重要目标，具有许多潜在的实际应用。在化学部门化学催化项目的资助下，密苏里大学堪萨斯城分校的Moteki博士正在开发具有多种不相容催化剂位点的合成材料，这些位点在空间上是隔离的。与内布拉斯加州科尔尼大学的Palencia博士一起，正在测试这些催化剂的催化效率和反应范围。Drs。Moteki和Palencia正积极从当地的高中和社区大学招募学生，以少数族裔学生为目标，为他们提供早期的研究经验。研究经验将增加保留，并加强在STEM领域服务不足的人口。还为社区和小型学院教师举办了夏季讲习班。这些努力对于培养新一代的年轻研究科学家至关重要。串联催化反应被广泛认为是最有效的原子经济和环境友好的过程之一，因为它产生的废物最少。特别是正交串联催化，它具有两种或两种以上不同的催化剂，具有不同的机制，提供了更高的工艺效率的潜力。在过去的几十年里，只有少数成功的例子被报道，这主要是由于创建空间上分离不相容催化剂的分隔宏观结构的困难。本提案旨在通过手性自分辨构建多组分催化树状大分子配合物，通过金属-手性配体相互作用实现各种多结构域树状大分子的原位定量组装。这使得微环境的调整比传统的共价组装系统容易得多，使其成为针对各种多步骤串联化学转化的反应筛选更有吸引力的系统。我们的研究小组旨在通过改变极性以及每个催化域的结构设计来了解双催化树状大分子的潜在催化剂结构-功能关系。此外，将通过三种不同类型的串联反应作为模型，研究双催化树状大分子的效率和通用性；I)底物选择性串联催化，ii)催化可逆步骤的串联反应，以及iii)竞争性催化途径的串联反应。操作简单的反应筛选和树突制备合成步骤是培养下一代合成化学家的理想选择。Moteki博士和Palencia博士积极参与外展活动，他们将举办一个年度研讨会，作为从当地高中和社区大学招募缺乏服务的少数民族学生的手段，在他们的研究小组中进行暑期研究实习。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。

In living cells many simultaneous chemical transformations occur with no interference between the enzymes that catalyze them. To accomplish this Nature has evolved to incorporate catalyst sites within enzyme pockets or by physical separation using membranes. The successful construction of artificial analogues of such frameworks would reduce catalyst deactivation and eliminate undesirable side reactions. These are important goals in catalysis with many potential practical applications. With funding from the Chemical Catalysis Program of the Chemistry Division, Dr. Moteki of the University of Missouri Kansas City is developing synthetic materials possessing multiple types of incompatible catalyst sites where the sites are spatially isolated. Together with Dr. Palencia of the University of Nebraska Kearney, the catalytic efficiency and reaction scope of these catalysts are being tested. Drs. Moteki and Palencia are actively recruiting students from local high schools and community colleges, targeting underrepresented minority students, and providing them with early research experience. The research experience will increasing retention, and enhancement of underserved populations in STEM field. Summer workshops for community and small college faculty are also being conducted. Such efforts are crucial in forming new generations of young research scientists.Tandem-catalyzed reactions have been widely recognized as one of the most efficient atom economical and environmentally friendly processes, due to minimization of waste generation. In particular, orthogonal tandem catalysis, which features two or more distinct catalysts with differing mechanisms, offers potential for higher process efficiency. Over the past few decades only a handful of successful examples have been reported primarily due to the difficulty in creating compartmented macro-structures that spatially separate incompatible catalysts. This proposal aims at building a multi-component catalytic dendrimer complex via chiral self-discrimination, which enables the in situ quantitative assembly of various multi-domain dendrimers through metal-chiral ligand interactions. This allows tuning of the microenvironment far easier than conventional covalently assembled systems, making it a more attractive system for reaction screening targeting various multi-step tandem chemical transformations. Our research team aims to understand the underlying catalyst structure-function relationship of the dual catalytic dendrimer by varying polarity as well as architectural design of each catalytic domains. In addition, the efficiency and versatility of dual catalytic dendrimers will be investigated, by using three different types of tandem reactions as models; i) substrate-selective tandem catalysis, ii) tandem reaction involving a catalytically reversible step, and iii) tandem reaction involving competitive catalytic pathways. The operational simplicity in reaction screening and the dendron preparation synthetic steps is ideal for training the next generation of synthetic chemists. Dr. Moteki and Dr. Palencia are actively engaged in outreach activity, they will host an annual workshop as means of recruiting of underserved minority students from local high schools and community colleges for summer research internship in their research groups.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.