Xanthenes especially benzoxanthenes are an important class of organic compounds that attracted the attention of organic chemists because of their wide range of biological and pharmaceutical properties such as anti inflammatory, antiviral activity, and agricultural bactericide activity. Furthermore, these compounds are very important in the industry because they are used as a local-dyes, in fluorescent material for visualization of biomolecules, Photodynamic therapy (PDT) and in laser technologies 1-2. Recently, solid acid catalyst has gained special attention as catalyst in organic synthesis because of the excellent solubility in water, uncomplicated handling, inexpensiveness, eco-friendly nature and readily available3-4.In this research, Fe3O4@SiO2@COOH as an effcient and reusable catalyst has been used for the one-pot preparation of 1,8-dioxo-octahydroxanthene derivatives via condensation between various aromatic aldehydes with dimedone under solvent-free and thermal conditions. We were able to recycle this catalyst (Fe3O4@SiO2@COOH)five times and use it in reaction, without reducing the efficiency of the product.
