Naniwa Shimpei, Hishitani Shinichiro, Yamamoto Akira, Yoshida Hisao
Department of Interdisciplinary Environment, Graduate School of Human and Environmental Studies, Kyoto University, Yoshida Nihonmatsu-cho, Sakyo-ku, Kyoto 606-8501, Japan.
Phys Chem Chem Phys. 2021 May 19;23(19):11366-11373. doi: 10.1039/d1cp00496d.
Dehydrogenative cross-coupling (DCC) between pyridine and benzene proceeded selectively using a TiO2 photocatalyst under visible light irradiation at optimized concentrations of the substrates. Visible light induces ligand-to-metal charge transfer (LMCT) between pyridine and a TiO2 surface to give a pyridine radical cation, which produces a pyridyl radical by its deprotonation or oxidation of another pyridine molecule. The pyridyl radical attacks a benzene ring to form an sp2C-sp2C bond and a hydrogen atom is subsequently removed to complete DCC. Selective excitation of the pyridine LMCT complex in the presence of an excess amount of benzene would be the key for higher selectivity.
在可见光照射下，使用二氧化钛光催化剂，在底物的优化浓度下，吡啶与苯之间的脱氢交叉偶联（DCC）反应具有选择性地进行。可见光诱导吡啶与二氧化钛表面之间的配体到金属的电荷转移（LMCT），生成吡啶自由基阳离子，该阳离子通过去质子化或氧化另一个吡啶分子产生吡啶基自由基。吡啶基自由基攻击苯环形成sp2C-sp2C键，随后去除一个氢原子以完成DCC反应。在过量苯存在下选择性激发吡啶LMCT络合物将是实现更高选择性的关键。
