Unexpected Scholl Reaction of 6,7,13,14-Tetraarylbenzo[k]tetraphene: Selective Formation of Five-Membered Rings in Polycyclic Aromatic Hydrocarbons
Unexpected Scholl Reaction of 6,7,13,14-Tetraarylbenzo[k]tetraphene: Selective Formation of Five-Membered Rings in Polycyclic Aromatic Hydrocarbons
复制标题
DOI：
10.1021/jacs.5b10399
复制
发表时间：
2016-03-02
影响因子：
15
通讯作者：
Muellen, Klaus
中科院分区：
文献类型：
--
作者：
Liu, Junzhi;Narita, Akimitsu;Muellen, Klaus
环脱氢是一种用途广泛的反应，可以合成多种多环芳烃(PAHs)。我们现在描述了6，7，13，14-四芳基苯并[k]四苯的一个独特的Scholl反应，它出人意料地形成了五元环，并伴随着高选择性的芳基1，2-移动。通过单晶X-射线、核磁共振、紫外-可见吸收光谱和循环伏安分析，全面研究了所合成的五元环双并三烯类似物的几何和光电性质。此外，还提出了一种可能的机理来解释芳基重排导致的选择性五元环的形成，这可以用密度泛函理论(DFT)计算来解释。理论结果表明，含五元环的二茂铁烯类似物的形成是受动力学控制的，而含六元环的预期产物在热力学上更有利。这些实验和理论结果提供了对仍有争议的肖尔反应机理的进一步洞察，并通过编程在肖尔反应期间进行原本不可预测的重排，为扩大多环芳烃的种类开辟了前所未有的领域。
Cyclodehydrogenation is a versatile reaction that has enabled the syntheses of numerous polycyclic aromatic hydrocarbons (PAHs). We now describe a unique Scholl reaction of 6,7,13,14-tetraarylbenzo[k]tetraphene, which unexpectedly forms five-membered rings accompanying highly selective 1,2-shift of aryl groups. The geometric and optoelectronic nature of the resulting bistetracene analogue with five-membered rings is comprehensively investigated by single-crystal X-ray, NMR, UV-vis absorption, and cyclic voltammetry analyses. Furthermore, a possible mechanism is proposed to account for the selective five-membered-ring formation with the rearrangement of the aryl groups, which can be rationalized by density functional theory (DFT) calculations. The theoretical results suggest that the formation of the bistetracene analogue with five-membered rings is kinetically controlled while an expected product with six-membered rings is thermodynamically more favored. These experimental and theoretical results provide further insights into the still controversial mechanism of the Scholl reaction as well as open up an unprecedented entry to extend the variety of PAHs by programing otherwise unpredictable rearrangements during the Scholl reaction.