Enantiopure Assembly of M4L6 Supramolecular Clusters with Different Sizes and their Application to Asymmetric Organic Reactions

在过去的几十年里，超分子结构的空腔内的反应的性能限制已经成为一种新的方法来选择性催化体系。最初在1998年报道，Raymond和同事合成了具有[Ga 4L 6]12-化学计量比的超分子主体配合物。该组装体已被用作超分子催化剂，导致增加的反应速率和改善的选择性。然而，尽管这类催化剂的多功能性，它们在不对称催化中的应用仍然是一个重要的目标。在与Robert Bergman教授和Dean Toste教授的密切合作下，我正在Raymond教授的团队中进行两个项目，以扩展M4 L 6四面体的丰富化学。我成功地合成了一种新型的对映体纯配体，它的骨架中含有氨基酸。相应的较大的和对映体纯的四面体的结构和催化研究目前正在调查中。在第二个项目中，较少建立的化学还原电荷自组装[Ti 4L 6]8-和[Ge 4L 6]8-进行了探索。两种簇合物均成功合成，并首次采用微波辅助自组装方法合成了Ti_4L_6四面体。为了比较[Ge 4L 6]8-和[Ga 4L 6]12-的催化效率，目前正在进行超分子介导的Aza-Cope重排作为模型反应。这将回答超分子笼的电荷是否影响其催化效率这一尚未解决的问题。

In the past decades, the performance of reactions constrained within the cavity of supramolecular structures has emerged as a novel approach toward selective catalytic systems. Initially reported in 1998, Raymond and co-worker synthesized a supramolecular host complex having [Ga4L6]12- stoichiometry. This assembly has been employed as a supramolecular catalyst resulting in increased reaction rates and improved selectivity. However, despite the versatility of this class of catalysts, their application in asymmetric catalysis remains an important goal. In close collaboration with Professor Robert Bergman and Professor Dean Toste, I am working on two projects in the group of Professor Raymond to extend this rich chemistry of M4L6 tetrahedron. I successfully synthesized a novel enantiopure ligand which incorporates amino acids in its backbone. Structural and catalytic studies of the corresponding larger and enantiopure tetrahedron are currently under investigation. In the second project, the less established chemistry of the reduced charge self-assemblies [Ti4L6]8- and [Ge4L6]8- are explored. Both cluster were successfully synthesized and a microwave -assisted self-assembly procedure was used for the first time to synthesize the Ti4L6 tetrahedron. In order to compare the catalytic efficiencies of [Ge4L6]8- and [Ga4L6]12-, a supramolecular-mediated Aza-Cope rearrangement as model reaction is currently underway. This will answer the yet open question whether the charge of supramolecular cage influences its catalytic efficiency.