Oxidation reactions of 1,2-diarylbenzenes induce intramolecular C–C bond formation. The substrates studied were prepared by the stepwise Suzuki–Miyaura coupling reaction that introduced 2-naphthyl, 2-anthranyl, and 2-pyrenyl groups on the ortho-positions of benzene. The subsequent oxidation reaction with FeCl3 induced an oxidative C–C bond formation reaction in the interior regions of the molecules. In marked contrast to our previous observations, two C–C bonds were formed. Theoretical calculations indicated that large spin densities at the reaction positions of the bis(cation radical) and/or cation radical species are needed for the C–C bond formation. The π-expanded molecules obtained showed bathochromic shifts in the absorption spectra.

中文翻译：

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1,2-二芳基苯的氧化分子内 C-C 键形成反应：高度共轭双桥多环芳烃的合成

1,2-二芳基苯的氧化反应诱导分子内 C-C 键的形成。研究的底物是通过逐步 Suzuki-Miyaura 偶联反应制备的，该反应在苯的邻位引入 2-萘基、2-蒽基和 2-芘基。随后与 FeCl3 的氧化反应在分子的内部区域诱导了氧化 C-C 键形成反应。与我们之前的观察结果形成鲜明对比的是，形成了两个 C-C 键。理论计算表明，C-C 键的形成需要双（阳离子自由基）和/或阳离子自由基物种的反应位置处的大自旋密度。获得的 π 扩展分子在吸收光谱中显示出红移。