Clean synthesis of 1,8-dioxooctahydroxanthenes promoted by DABCO-bromine in aqueous media

Abstract An efficient procedure is reported for the synthesis of 3,3,6,6-tetramethyl-9-aryl-1,8-dioxooctahydroxanthenes using a one-pot condensation of arylaldehydes and 5,5-dimethyl-1,3-cyclohexandione in the presence of DABCO-bromine (TDB) as an acid catalyst. To the best of our knowledge this is the first time that DABCO-bromine is used as an acid catalyst in aqueous media for this type of reaction. This method provides several advantages such as use of water as solvent, easy and clean synthesis, simple work up and versatility.