Synthesis of 6H-Dibenzopyrans via an Unsymmetrical Aryl-Aryl Cross-Coupling

Significance

In continuation of the important discovery of norbornene for catalytic C-C bond formation, Catellani reports an efficient three-component reaction for the synthesis of 6H-dibenzopyran derivatives from easily available aryl iodides, phenols, and acrylates. The reaction involves an intriguing three-bond-forming process and proceeds in moderate to good yields. A mechanistic rationale for the necessity of norbornene in the catalytic cycle is given.