Pd-Catalyzed Formal [3+3] Heteroannulation of Allylic gem-Diacetates: Synthesis of Chromene-Based Natural Products and Exploration of Photochromic Properties

Palladium-catalyzed allylic alkylation reactions of allylic gem-diacetates are rarely explored. This work unveils an unusual chemical reactivity pattern of allylic gem-diacetates and establishes them as new prototypes to synthesize complex benzo[f]chromene systems. Under the reaction conditions, the diacetates behave as 1,3-dicationic equivalents and undergo a [3 + 3] heteroannulation with 2-naphthols (and meta-substituted phenols) to produce novel polycyclic chromenes possessing spiro-, tri-, and tetrasubstituted carbon centers. The versatility of the method is demonstrated in the synthesis of several chromene-based bioactive natural products. Further, interesting photochromic properties of the new classes of benzo[f]chromenes are also discovered.

Automated summary

This study reveals a new chemical reactivity pattern of allylic gem-diacetates and successfully synthesizes complex benzo[f]chromene compounds, demonstrating the versatility of the method. Additionally, interesting photochromic properties of the new classes of benzo[f]chromenes are discovered.