新型有机铯配合物的合成、表征及其在碳-杂键形成反应中的催化应用研究

Cesium is an important heavy alkali metal element, the reserves of cesium resources in China are among the highest in the world; however, there are only few basic researches on this area. Based on the existing special features and the potential application prospects of cesium complexes, this project proposed new ideas for design and synthesis of new organocesium complex catalysts and for their applications in various important organic reactions such as carbon-heteroatom (sulfur, selenium, tellurium, phosphorus) bonds forming reactions. The relationship between the structure and catalytic activity of the complexes will be clarified. In this proposal, the adopted ligands are calixcrown compounds and can coordinate or form π-metal bond with empty orbitals of cesium ion. Ligands can be equipped with one or more cesium metal ions to form organic cesium cations, and their corresponding anions can be separated from the metal centers, or can also be formed hydrogen bonds with the pyrrole XH groups in the ligand. By the modulation of calixarene skeleton and the functional species of the crown ether chain of the calixcrown, the interaction ability of cesium metal center with the anion and cesium chemical environment will be modulated, and then the physical and chemical properties and catalytic performance of the organocesium complex can be modified. It is expected to obtain a series of new organocesium complex catalysts with good application prospect and our own intellectual rights, it is also expected to play a major role in the organic catalytic synthesis technology, and provide important references for the development of new organometallic compounds and rational utilization of cesium resources. Therefore, the project has an important scientific and practical value.

铯是一种重要的碱重金属元素，我国铯资源的储量位居世界前列，但是基础研究开发工作较少。针对铯化合物已有特性和潜在应用前景，本申请项目提出设计和合成新型有机铯配合物催化剂的新理念，并探讨它们在碳－杂（硫、硒、碲、磷）键形成等重要有机反应中的应用，深入研究其构-效关系。拟设计和采用可与铯离子空轨道形成配位键和π-金属键的冠醚杯芳烃作为配体。配体可与一个或多个铯金属离子配位形成有机铯阳离子，而其对应阴离子可游离于配合物金属中心，也可与位于配体中的吡咯等XH基团形成氢键。拟通过调变杯芳烃的骨架以及冠醚链的功能基调变铯金属中心及其阴离子的相互作用力及其化学环境，从分子水平调变有机铯配合物的物化性质和催化性能。本项目的实施，有望得到具有应用前景和我国完全自主知识产权的有机铯配合物催化剂，也将对有机催化合成技术产生重要影响，并为开发金属有机配合物和利用铯金属资源提供重要参考，具有重要的科学意义和应用价值。

本项目研究内容基本按照研究计划进行，首先，设计并合成了四个全新的杯芳烃配体，采用1H NMR、13C NMR和MS对其结构进行了表征、确证，并探讨了该类杯芳烃配体在碳-杂（S、Se）键形成反应中的应用。同时，对铯离子与杯芳烃配体的作用机理进行了系统考察，结果表明主要是带正电的铯离子与富电子基团（如O、N、芳基等）之间的相互作用。基于以上机理，探讨了铯催化下富电子基炔烃与二芳基二硫醚/二芳基二硒（碲）醚二元体系反应，“一锅法”高立体、区域选择性地构建含有多个碳-杂键的烯烃化合物。并以该杂取代烯烃作为平台分子，通过逐步组装方法成功制备了高纯度的四取代烯烃，为四取代烯烃的制备提供了一个普遍性的方法。在四取代烯烃的制备研究中，我们发现(Z)-1,2-二芳硫基烯烃中处于不同化学环境下的两个C-S键同样可以在合适的催化体系下实现选择性断裂，从而构建四取代烯烃。同时，开展了 “C=S”键的构建、铯催化下联烯的合成、3-芳硫基吲哚的合成以及铯催化下茚醛缩合等研究工作。一共合成了250多个化合物，采用氢谱、碳谱、质谱、高分辨质谱和单晶衍射等方法对目标产物进行表征、确证，并通过理论计算、核磁跟踪实验和氘代实验等控制实验对反应进行的可能机理进行了系统研究。在本项目资助下，已申请发明专利10余项，发表期刊论文24篇，主要发表在Org. Lett., J. Org. Chem., Adv. Synth. Catal., J. Organomet. Chem., Tetrahedron Lett., Tetrahedron等国际重要期刊上。