铜参与的碳硼烷锂盐与炔基锂的交叉偶联反应：“一锅法”合成C-炔基邻碳硼烷衍生物

Copper(I)-Mediated Cross-Coupling Reaction of Carboranyl-lithium with Alkynyllithium: One-Pot Synthesis of C-Alkynyl-o-carboranes

室温下氯化亚铜参与的邻碳硼烷双锂盐Li2C2B10H10的白偶联反应，除了生成预期产物联邻碳硼烷（2），还生成少量由邻碳硼烷锂盐和（为邻碳硼烷o-C2810H12锂化反应而引入的）过量丁基锂交叉偶联的产物1-丁基邻碳硼烷（4）和1,2-二丁基邻碳硼烷（5），而氯化亚铜参与的邻碳硼烷、端炔、丁基锂的反应体系能够“一锅法”合成炔基邻碳硼烷（产率33－62％）．化合物5可由碳硼烷双锂盐与过量的1-溴丁烷反应获得（产率84．6％）．对化合物5与炔基碳硼烷衍生物通过核磁共振（1H，13C，11B）、红外光谱、质谱以及单晶X射线衍射（5）等手段进行了结构表征，并对其可能的生成机理进行了探讨．

In the copper（I）-mediated homocoupling reaction of dilithio-o-carborane Li2C2B10H10 at room temperature, the expected product 1, 1＇-bis（o-carborane） （2）, the unexpected compounds 1-butyl-o-carborane （4） and 1,2-dibutyl-o-carborane （5） were obtained, the latter two being formed by the cross-coupling reaction of o-carboranyllithium with n-butyllithium （intro- duced for the lithiation of o-carborane C2B10H12）. Based on this finding, the CuCl-mediated one-pot synthesis of C-alkynyl-o-carborane derivatives （yield 33%~62%） involving o-carborane, terminal alkynes and n-butyllithium was devel- oped. It was found that the product distribution varied with the amount of n-BuLi and CuC1 utilized. Compound 5 was separately prepared in a good yield （84.6%） via the reaction of dilithio-o-carborane with excess 1-bromobutane at reflux for 23 h. The structural characterization of compound 5 and the C-alkynyl-o-carboranes were carried out by means of NMR, IR, MS and single-crystal X-ray diffraction （5）. The possible mechanism for the formation of the cross-coupling products is also discussed.