Titanocene-Mediated Dinitrile Coupling: A Divergent Route to Nitrogen-Containing Polycyclic Aromatic Hydrocarbons
Titanocene-Mediated Dinitrile Coupling: A Divergent Route to Nitrogen-Containing Polycyclic Aromatic Hydrocarbons
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茂钛介导的二腈偶联：制备含氮多环芳烃的不同途径
DOI：
10.1021/jacs.7b13823
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发表时间：
2018
影响因子：
15
通讯作者：
Tilley, T. Don
中科院分区：
文献类型：
--
作者：
Kiel, Gavin R.;Samkian, Adrian E.;Nicolay, Amélie;Witzke, Ryan J.;Tilley, T. Don
报道了构建大型含氮多环芳烃（PAH）的通用合成策略。该策略涉及两个关键步骤：（1）二茂钛介导的低聚（二腈）前体的还原环化，形成附加有二（氮杂）钛环戊二烯官能团的PAH； (2) 发散的二茂钛转移反应，允许在最后一步将一个或多个醌、二唑或吡嗪单元安装到 PAH 框架中。新方法能够对 HOMO 和 LUMO 能级进行合理的后期控制，从而实现光物理和电化学特性，如紫外/可见光和荧光光谱、循环伏安法和 DFT 计算所揭示的那样。更一般地说，这一贡献代表了二（氮杂）金属环戊二烯中间体在有机合成中的首次生产性应用，包括第一个形成吡嗪环的正式[2 + 2 + 2]反应。
A general synthetic strategy for the construction of large, nitrogen-containing polycyclic aromatic hydrocarbons (PAHs) is reported. The strategy involves two key steps: (1) a titanocene-mediated reductive cyclization of an oligo(dinitrile) precursor to form a PAH appended with di(aza)titanacyclopentadiene functionality; (2) a divergent titanocene transfer reaction, which allows final-step installation of one or moreo-quinone, diazole, or pyrazine units into the PAH framework. The new methodology enables rational, late-stage control of HOMO and LUMO energy levels and thus photophysical and electrochemical properties, as revealed by UV/vis and fluorescence spectroscopy, cyclic voltammetry, and DFT calculations. More generally, this contribution presents the first productive use of di(aza)metallacyclopentadiene intermediates in organic synthesis, including the first formal [2 + 2 + 2] reaction to form a pyrazine ring.