Pd/NHC催化o-碳硼烷B(3,6)-H键的选择性官能化及反应机理研究

具有正二十面体结构和三维芳香性的o-碳硼烷以其独特的光电、生化特性，在材料科学、配位化学以及药物化学等领域具有重要的应用前景。由于o-碳硼烷含有10个不完全等价的B-H键，且相互之间反应活性差异甚微，使得其选择性官能化成为了一个非常有挑战性的课题。基于o-碳硼烷与芳香烃在反应特性上的相似性，本课题根据o-碳硼烷的结构特点和电子特性，以富电子的过渡金属催化剂活化缺电子的B(3,6)-H键为切入点，拟利用NHC的强σ-供电子能力和金属键合能力，以咪唑盐作为NHC前体与Pd(OAc)2原位形成的Pd-NHC催化B-H键的活化策略实现o-碳硼烷B(3,6)-H的选择性活化，探索C-B键和硼-杂原子键选择性构建的方法；揭示B(3,6)-H键选择性活化的反应机理和普遍规律。对于丰富硼官能化o-碳硼烷衍生物的合成方法、促进o-碳硼烷在相关学科领域的应用具有重要意义。

In recent years, o-carborane, featured with icosahedron and three-dimensional aromaticity, has received much attention due to its unique photoelectric and biochemistry characteristic, and has important potential application in materials science, coordination chemistry and pharmaceutical chemistry etc.. Due to the 10 B-H bonds of o-carborane are not fully equal and only have slightly difference in reactivity, thus led the selective functionalization of B-H bond to be a challenge subject. Based on the similar reactivity of o-carborane with arenes and the structure characteristic of o-carborane, we envisioned to utilize the electron-rich transition metal catalyst to activate the electron-deficient B(3,6)-H bonds. With this idea in mind, by employing the strong σ-donating ability and bonding capability of N-heterocyclic carbene, we intend to utilize the in situ formed Pd-NHC to exploring the selective activation of B(3,6)-H bonds and methodologies for construction of carbon-boron and boron-heteroatom bonds. Through our effects, we would disclose the mechanism and general rules for activation of B(3,6)-H bonds. It has important meaning in enriching the synthetic methods of boron functionalized o-carborane derivatives and promoting their application in related disciplines.