An efficient solvent-free synthesis of 1,8-dioxo-octahydroxanthenes using Fe2(SO4)3.7H2O as catalyst

A facile and efficient protocol for the synthesis of 1,8-dioxo-octahydroxanthenes has been developed by one-pot Knoevenagel condensation, Michael addition and cyclodehydration reaction of dimedone (active methylene carbonyl compound) with aromatic aldehydes in the presence of Iron (III) sulfate hydrate as a solid acidic catalyst under solvent-free conditions. Various aromatic aldehydes were utilized in the reaction and in all situations the desired product were synthesized successfully. The present methodology is cost-effective in addition to other advantages like high yields of products in shorter reaction time and simple workup procedure. The non toxicity and easy availability of the catalyst makes this protocol efficient and environmentally benign.