Wang Tongdao, Han Feifei, Huang Haiping, Li Jinhua, Zhang Hong, Zhu Jun, Lin Zhenyang, Xia Haiping
State Key Laboratory of Physical Chemistry of Solid Surfaces and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), and Department of Chemistry, Xiamen University, Xiamen 361005, China.
1] State Key Laboratory of Physical Chemistry of Solid Surfaces and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), and Department of Chemistry, Xiamen University, Xiamen 361005, China [2] Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
Sci Rep. 2015 Apr 9;5:9584. doi: 10.1038/srep09584.
The concept of aromaticity has long played an important role in chemistry and continues to fascinate both experimentalists and theoreticians. Among the archetypal aromatic compounds, heteroaromatics are particularly attractive. Recently, substitution of a transition-metal fragment for a carbon atom in the anti-aromatic hydrocarbon pentalene has led to the new heteroaromatic osmapentalenes. However, construction of the aza-homolog of osmapentalenes cannot be accomplished by a similar synthetic manipulation. Here, we report the synthesis of aza-osmapentalenes by sequential ring contraction/annulation reactions of osmabenzenes via osmapentafulvenes. Nuclear magnetic resonance spectra, X-ray crystallographic analysis, and DFT calculations all suggest that these aza-osmapentalenes exhibit aromatic character. Thus, the stepwise transformation of metallabenzenes to metallapentafulvenes and then aza-metallapentalenes provides an efficient and facile synthetic route to these bicyclic heteroaromatics.
芳香性的概念在化学领域长期以来一直发挥着重要作用，并且持续吸引着实验学家和理论家。在典型的芳香族化合物中，杂芳烃尤其具有吸引力。最近，在反芳香烃戊搭烯中用过渡金属片段取代一个碳原子，得到了新型杂芳烃锇戊搭烯。然而，通过类似的合成操作无法完成锇戊搭烯的氮杂同系物的构建。在此，我们报道了通过锇苯经由锇戊富烯的连续环收缩/环化反应合成氮杂锇戊搭烯。核磁共振光谱、X射线晶体学分析和密度泛函理论计算均表明这些氮杂锇戊搭烯具有芳香性特征。因此，金属苯逐步转化为金属戊富烯，然后再转化为氮杂金属戊搭烯，为这些双环杂芳烃提供了一条高效且简便的合成路线。
