Palladium/Norbornene Cooperative Catalysis 2-Fold C–H/C–X Coupling: Construction of Polycyclic Aromatic Hydrocarbons from Brominated Benzimidazoles

A palladium/norbornene (NBE)-catalyzed 2-fold C-H/C-X coupling reaction of aryl iodides is reported. Bromine-substituted benzimidazoles were chosen as electrophilic and termination reagents, and the versatile polycyclic aromatic hydrocarbon products were successfully obtained. The strategy overcomes the challenge of catalyst poisoning by heterocyclic substrates. In addition, the imidazole moiety in the product is endowed with a localization role, thus enabling the compounds to be applied in a wider synthetic scenario, and the fluorescence persisted. Furthermore, the bioactivity evaluation has identified three promising leading compounds 3b, 4e, and 4i.