基于镍杂五元环的碳硼烷衍生化方法学研究

Carboranes as a class of structurally unique molecules with exceptionally thermal and chemical stabilities, are finding many applications in medicinal chemistry, supramolecular design, and catalytic process. However, their unique structures make derivatization difficult. Only limited methodologies for the derivatization of these clusters are known. In view of the spectacular role of transition metals in synthetic chemistry, we plan in this proposal to use the efficient yet cheap nickel metal to develop new transition metal-mediated/catalyzed synthetic methodologies for functional carborane derivatives. The synthesis and reactivity study of five-membered nickelacycles bearing a carborane moiety toward unsaturated substrates can lead to the formation of a series of carborane containing molecules with conjugated moiety, macrocyclic or heterocyclic structures that cannot be prepared by conventional methods. We plan to systematically analyze the relationship between structures and reactivities of metal complexes to develop new systems that display both high reactivity and predictable selectivity; explore multicomponent cross-coupling reactions to assemble complex carborane derivatives from very simple precursors in a single operation by using unsaturated substrates with different activities. On the other hand, the B-functionalization of carboranes are expected by using organometallic methods due to the similarity between 1,3-dehydro-o-carborane and 1,2-dehydro-o-carborane. It is anticipated that the results of this work would break a new ground in the exploration of metal-carboranyl chemistry, and the methodologies for carborane derivatization are also of fundamental importance for synthetic chemistry.

鉴于碳硼烷化合物在医药、材料、催化等方面的广泛应用及其衍生化方法相对缺乏的现状，发展新型碳硼烷衍生化方法、设计并合成新型碳硼烷化合物对于推动碳硼烷化学的发展具有重要的理论和现实意义。由于已知方法在合成一系列含特殊结构（如大环、杂环）碳硼烷衍生物方面的缺失与不足，本项目建立在金属有机化学基础上，拟通过含碳硼烷基团镍杂五元杂环的合成与反应性研究，发展一系列新型碳硼烷衍生化方法。利用高效、廉价的金属镍介导/催化反应，在温和的反应条件下利用方便易得、廉价的原料合成已知方法不能制备的包括含有不饱和体系、大环、杂环等结构的新颖官能团化碳硼烷衍生物。并由过渡金属催化或介导反应实现碳硼烷硼顶点官能团化。发展多组份反应或分步串联反应，在保持高反应效率的同时得到高反应选择性。研究镍杂五元环的反应机制，为其它金属催化有机方法学研究提供有利的借鉴。

项目执行四年来，我们开展了针对碳硼烷并金属杂五元环化合物反应性的研究，发展了基于金属杂碳硼烷并环戊烷与系列底物的插入及转金属反应合成新型碳硼烷并碳环、杂环的新方法；利用碳硼炔作为重要合成子与胺基锂、呋喃、富烯等反应制备新型碳硼烷衍生物并研究了其化学转化；实现了铱催化的碳硼烷3,6位硼氢键选择性硼基化及后续向含碳硼烷B-X键 (X = O, N, C, I, Br)化合物的官能团转化。本项目提供了碳硼烷官能团化路线设计的新思路，发展了多项碳硼烷碳和硼顶点上高效、高选择性的衍生化方法，合成一系列新颖结构的碳硼烷衍生物。主要成果如下：.1. 共发表学术论文12 篇。其中在J. Am. Chem. Soc.发表1篇，在Angew. Chem. Int. Ed.发表2 篇，在Nat. Commun.发表1篇；在Org. Chem. Front., Chin. J. Chem., Dalton Trans.等期刊发表7 篇；应邀在Tetrahedron Lett.撰写过渡金属促进碳硼烷官能团化研究进展综述1篇。.2. 本项目研究人员中有1 人取得博士学位，2 人取得硕士学位，1 人硕士生转博。.3. 本项目相关研究工作在国际学术会议做口头报告3次。