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. [ABSTRACT FROM AUTHOR]