An efficient synthesis of 1,8-dioxo-octahydroxanthenes using heterogeneous catalysts

1,8-Dioxo-octahydroxanthenes have efficiently been synthesized from 5,5-dimethyl-1,3-cyclohexanedione and aromatic aldehydes using silica supported sodium hydrogen sulfate (NaHSO4 · SiO2) or silica chloride as a heterogeneous catalyst. The experimental procedure is very simple and the products are formed in high yields.