Self-Assembled Catalysts for Asymmetric Ring Opening Reactions

该项目将开发新型双核催化剂用于不对称开环反应，如末端环氧化物的水解动力学拆分(HKR)。它采用了一种极具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。它旨在开发一种高效、绿色的环氧化物HKR工艺，实现无溶剂条件、极低的催化剂负载量和催化剂回收/再循环。首先，设计并合成了能够通过尿素-尿素氢键自组装的新型席夫碱配体。其次，对自组装双核催化剂在环氧化物水解动力学拆分中的有效性进行了评价。第三，对双脲基席夫碱金属络合物在溶液中的自缔合行为进行了详细的研究，考察了自组装与HKR反应速率的相关性。此外，还将通过引入额外的非共价键相互作用来探索金属有机胶凝作用，这些作用将被引入到双尿素基席夫碱金属配合物中。在化学合成项目的这一奖项的支持下，佛罗里达大学化学系的洪素原教授正在开发高效、环保的工艺，利用少量可回收催化剂，在无溶剂的条件下将廉价的原料转化为有价值的合成构件。这项拟议的研究采取了一种非常创新的方法，将两个不同的化学学科结合起来：超分子化学和过渡金属催化的转化。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，使两个金属活性中心接近，这是发生双金属转变的先决条件。这一新的策略可以适用于广泛的不对称反应，并可以对开发更高效、环境友好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，包括代表人数不足的群体提供一个极好的机会。

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.