Self-Assembled Catalysts for Asymmetric Ring Opening Reactions

本项目将开发用于末端环氧化物水解动力学拆分（HKR）等不对称开环反应的新型双核催化剂。它采用了一种非常有吸引力的超分子方法，可以通过单体单元的自组装在溶液中快速构建多核系统。它旨在通过实现无溶剂条件、极低的催化剂负荷和催化剂回收/再循环，开发一种高效、绿色的环氧化物HKR工艺。首先，设计和合成能够通过尿素-尿素氢键自组装的新型希夫碱配体。其次，评价了自组装双核催化剂在环氧化物水解动力学分解中的有效性。第三，将对双尿素功能化的希夫贱金属配合物在溶液中进行详细的自缔合研究，探讨自组装与HKR反应速率之间的关系。此外，有机金属凝胶化将通过引入额外的非共价键相互作用到双尿素功能化的希夫碱金属配合物中进行探索。在化学合成项目的支持下，佛罗里达大学化学系的Sukwon Hong教授正在开发高效、环保的工艺，利用少量可回收催化剂，在无溶剂条件下将廉价原料转化为有价值的合成材料。提议的研究采用了一种高度创新的方法，通过合并两个不同的化学学科：超分子化学和过渡金属催化转化。这种利用氢键组装金属催化剂的跨学科策略将提供一种新的有效方法，使两个金属活性位点接近，这是双金属转化发生的先决条件。这种新策略可以适用于广泛的不对称反应，并且可以对开发更有效，更环保的重要手性分子的工业过程产生重大影响。此外，由于其多学科性质，该项目将为教育和培训本科生和研究生提供极好的机会，包括代表性不足的群体。

This project will develop novel dinuclear catalysts for asymmetric ring opening reactions such as hydrolytic kinetic resolution (HKR) of terminal epoxides. It employs a highly attractive supramolecular approach which enables rapid construction of multinuclear systems in solution via self-assembly of monomeric units. It aims to develop a highly efficient, green process of HKR of epoxides by enabling solvent-free conditions, very low catalyst loading and catalyst recovery/recycle. First, new Schiff base ligands capable of self-assembly through urea-urea hydrogen bonding will be designed and synthesized. Second, the effectiveness of the self-assembled dinuclear catalysts in hydrolytic kinetic resolution of epoxides will be evaluated. Third, detailed self-association studies will be conducted on the bis-urea functionalized Schiff base metal complexes in solution to investigate the correlation between self-assembly and HKR reaction rate. In addition, organometallic gelation will be explored by introducing additional noncovalent bonding interactions to the bis-urea functionalized Schiff-base metal complexes. With the support of this award from the Chemical Synthesis Program, Professor Sukwon Hong, of the Department of Chemistry at the University of Florida, is developing highly efficient, environmentally friendly processes to convert inexpensive feedstocks to valuable synthetic building blocks under solvent free conditions using small amounts of recyclable catalysts. The proposed research takes a highly innovative approach by merging two different disciplines of chemistry: supramolecular chemistry with transition-metal catalyzed transformations. This interdisciplinary strategy using hydrogen bonding to assemble metal catalysts will provide a new efficient way to bring two metal active sites in close proximity which is a prerequisite for the bimetallic transformations to occur. This novel strategy can be applicable to a wide range of asymmetric reactions and can have a significant impact on the development of more efficient, environmentally friendly industrial processes for important chiral molecules. In addition, this project will provide an excellent opportunity to educate and train undergraduate and graduate students including underrepresented groups owing to its multidisciplinary nature.