One‐Step Annulative π‐Extension of Alkynes with Dibenzosiloles or Dibenzogermoles by Palladium/o‐chloranil Catalysis

Reliable and short synthetic routes to polycyclic aromatic hydrocarbons and nanographenes are important in materials science. Herein, we report an efficient one‐step annulative π‐extension reaction of alkynes that provides access to diarylphenanthrenes and related nanographene precursors. In the presence of a cationic palladium/o‐chloranil catalyst system and dibenzosiloles or dibenzogermoles as π‐extending agents, a variety of diarylacetylenes are transformed successfully into 9,10‐diarylphenanthrenes in a single step with good functional‐group tolerance. Furthermore, double π‐extension reactions of 1,4‐bis(phenylethynyl)benzene and diphenyl‐1,3‐butadiyne are demonstrated, affording oligoarylene products, which show potential for application in the synthesis of larger polycyclic aromatic hydrocarbons and nanographenes. Extending circumstances: An efficient one‐step annulative π‐extension reaction of alkynes provides facile access to diarylphenanthrenes and related nanographene precursors. In the presence of a cationic palladium/o‐chloranil catalyst system, a variety of diarylacetylenes are transformed through the use of dibenzosiloles or dibenzogermoles as π‐extending agents into 9,10‐diarylphenanthrenes with good functional‐group tolerance.