Helicate-based supramolecular switches in catalysis

催化中基于螺旋的超分子开关

• 批准号: 444762295
• 负责人: Professor Dr. Markus Albrecht
• 金额: --
• 依托单位: Institut für Organische Chemie (IOC)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/444762295?language=en
• 关键词: Helicate; based; supramolecular; switches; catalysis

Hierarchically assembled lithium-bridged helicates and lithium-dependent expandable/compressable helicates are introduced as platform for stereoselective reactions.In case of the hierarchically formed helicates a solvent dependent equilibrium between the dimeric helicate and the monomeric complex is observed. In case of enantiomerically pure ligands the sterochemical information at the complex is fixed, while in case of the monomer high dynamics and high sterochemical lability is found.The different forms of the expandable/compressable helicates can be interconverted by exchange of the cations. In case of enqantiomerically pure ligands, the helicates with opposite twist can be specifically obtained based on the cations which are present.Chemical reactions in the periphery are depending in reactivity and selectivity on the switching state of the helicate. This is used to control Diels-Alder reactions as well as sec. amine based organocatalysis, biphenol-based catalysis or catalysis with phosphane/phosphaamidite systems at the helicates and to influence or invert the stereoselectivity of the respective reaction.Appropriate enantiomerically pure and reactive helicates are obtained in two different approaches: (1) chiral ligands which bear the reactive units are introduced or (2) statistical heteroleptic complexes are formed with chiral, unreactive and achiral, reactive ligands.No new catalytic reactions will be developed but well known reactions will be performed at the helicates as novel platform for selectivity control.

介绍了多级组装的锂桥螺旋酸酯和锂依赖的可膨胀/可压缩螺旋酸酯作为立体选择性反应的平台，在多级组装的螺旋酸酯的情况下，观察到二聚体螺旋酸酯和单体络合物之间的溶剂依赖性平衡。在对映体纯配体的情况下，络合物的立体化学信息是固定的，而在单体的情况下，发现高动力学和高立体化学不稳定性。在对映体纯的配体中，根据存在的阳离子，可以特异性地得到具有相反扭转的螺旋化合物，其周围的化学反应的反应性和选择性取决于螺旋化合物的转换状态。这是用来控制狄尔斯-阿尔德反应以及sec。基于胺的有机催化、基于双酚的催化或用膦/亚磷酰胺体系在螺旋化合物上的催化，并影响或逆转相应反应的立体选择性。（1）引入带有反应单元的手性配体或（2）与手性、非反应性和非手性形成统计杂配配合物，反应性配体。不会开发新的催化反应，但将在螺旋状化合物上进行众所周知的反应，作为选择性控制的新型平台。