Heterogeneously Catalyzed Cascade Oxidative Coupling/Dearomative Spirocyclization of Diarylamines: Facile Access to Spiroacridines

Spirocyclic compounds, particularly spirocyclohexadienones, are important in pharmaceuticals due to their biological activity. In this study, we develop a catalytic cascade oxidative spirocyclization of diarylamines for the rapid access to highly functionalized spirocyclohexadienones. Using commercially available recyclable heterogeneous metal catalysts, cascade process via oxidative coupling and dearomative spiroannulation proceeds efficiently under mild aerobic conditions, providing spirocyclohexadienones fused with an acridine skeleton in good-to-excellent yields. This method provides efficient and rapid access to nitrogen-containing fused spiro compounds in a highly atom-economical and environmentally friendly manner.