Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka, 565-0871, Japan.
Frontier Research Base for Global Young Researchers, Graduate School of Engineering, Osaka University, Suita, Osaka, 565-0871, Japan.
Angew Chem Int Ed Engl. 2017 Oct 2;56(41):12746-12750. doi: 10.1002/anie.201707515. Epub 2017 Aug 31.
Arene-fused cyclooctatetraenes (COTs) possess unique structural and electronic properties that originate from their saddle-shaped π-conjugated architectures. Considerable attention has been paid to the transition-metal-mediated synthesis of these cyclic compounds; however, there have been limited achievements to date in the efficient construction of heteroarene-fused COTs. In this contribution, we report a novel Pd-catalyzed dehydrogenative cyclodimerization of biheteroarenes through four-fold C-H activation toward the synthesis of a series of heteroarene-fused COTs. A set of mechanistic investigations indicated the involvement of high-valent Pd species prior to the dimerization event in the catalytic cycle. The redox behavior of the obtained COTs is also described briefly.
芳环稠合环辛四烯（COTs）具有独特的结构和电子性质，源于其鞍形的π共轭架构。人们对过渡金属介导的这些环状化合物的合成给予了相当的关注；然而，迄今为止，在高效构建杂芳环稠合 COTs 方面的成果有限。在本研究中，我们报告了一种新型的 Pd 催化双杂芳烃的脱氢环二聚反应，通过四重 C-H 活化来合成一系列杂芳环稠合 COTs。一系列的机理研究表明，在催化循环中二聚化反应之前涉及高价 Pd 物种。此外，还简要描述了所得 COTs 的氧化还原行为。
