Palladium‐Catalyzed Synthesis of Heteroarene‐Fused Cyclooctatetraenes through Dehydrogenative Cyclodimerization

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.