Construction of Acenaphthylenes via C−H Activation-Based Tandem Penta- and Hexaannulation Reactions

Abstract Acenaphthylene-containing polycyclic aromatic hydrocarbons (AN-PAHs) are noteworthy structural motifs for organic functional materials due to their non-alternant electronic structure, which increases electron affinity. However, the synthesis of AN-PAHs has traditionally required multiple sequential synthetic steps, limiting structural diversity. Herein, we present a novel tandem C−H penta- and hexaannulation reaction of aryl alkyl ketone with acetylenedicarboxylate. This integrated approach enhances overall efficiency and selectivity, marking a significant advancement in AN-PAH synthesis. Mechanistic studies unveil an orchestrated extension of five- and six-membered rings through C−H activation-annulation and Diels–Alder reaction. Additionally, the tandem annulation reaction can be performed stepwise, further validating the proposed mechanism and increasing the structural diversity of AN-PAHs.