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。为了实现这一点，自然界已经进化到将催化剂位点并入酶口袋内或通过使用膜的物理分离。这种框架的人工类似物的成功构建将减少催化剂失活并消除不期望的副反应。这些都是催化领域的重要目标，具有许多潜在的实际应用。在化学部化学催化计划的资助下，密苏里州堪萨斯城大学的Moteki博士正在开发具有多种类型的不相容催化剂位点的合成材料，其中这些位点在空间上是孤立的。与内布拉斯加大学科尔尼分校的帕伦西亚博士一起，正在测试这些催化剂的催化效率和反应范围。Moteki博士和帕伦西亚博士正在积极从当地高中和社区大学招收学生，目标是代表性不足的少数民族学生，并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领域服务不足的人群。还为社区和小型学院教师举办了暑期讲习班。这种努力对于培养新一代的年轻研究科学家至关重要，串联催化反应由于最大限度地减少废物的产生而被广泛认为是最有效的原子经济和环境友好的过程之一。特别是正交串联催化，其特征在于具有不同机理的两种或更多种不同催化剂，提供了更高工艺效率的潜力。在过去的几十年里，只有少数成功的例子已经报道，主要是由于在空间上分离不相容的催化剂，在创建分区的宏观结构的困难。该方案旨在通过手性自识别构建多组分催化树枝状大分子复合物，从而能够通过金属-手性配体相互作用原位定量组装各种多结构域树枝状大分子。这使得微环境的调节比传统的共价组装系统容易得多，使其成为针对各种多步串联化学转化的反应筛选的更有吸引力的系统。我们的研究团队旨在通过改变极性以及每个催化域的结构设计来了解双重催化树枝状聚合物的潜在催化剂结构-功能关系。此外，双催化树枝状聚合物的效率和多功能性将进行研究，通过使用三种不同类型的串联反应作为模型; i）底物选择性串联催化，ii）涉及催化可逆步骤的串联反应，和iii）涉及竞争性催化途径的串联反应。反应筛选和树枝化基元制备合成步骤的操作简单性是培养下一代合成化学家的理想选择。Moteki博士和帕伦西亚博士积极参与外展活动，他们将举办年度研讨会，从当地高中和社区大学招募服务不足的少数民族学生，在他们的研究小组进行暑期研究实习。该奖项反映了NSF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.