Solvent‐free Synthesis of 1,8‐Dioxo‐octahydroxanthenes and Tetra‐hydrobenzo[a]xanthene‐11‐ones over Poly(N,N′‐dibromo‐N‐ethylnaphtyl‐2,7‐sulfonamide)

In this work, poly(N,N ′‐dibromo‐N ‐ethylnaphtyl‐2,7‐sulfonamide) (PDNES ) as a highly efficient catalyst was applied for the synthesis of 1,8‐dioxo‐octahydroxanthenes and tetra‐hydrobenzo[a]xanthene‐11‐ones under neutral and solvent‐free conditions.