Highly efficient, one-pot, solvent-free synthesis of 1,8-dioxo-octahydroxanthene derivatives by ZnMn2O4 nanoparticles as efficient heterogeneous catalyst

Xanthene derivatives have attracted considerable interest in both pharmaceutical and medicinal chemistry because of their numerous pharmacological properties such as antibacterial, antiviral, anti-inflammatory, or anticancer activities [1]. Furthermore, in addition to their use as valuable synthetic precursors for many organic compounds and dyes xanthene derivatives have also found use in laser technologies and fluorescent materials for visualization of biomolecules [2]. In recent years, spinel nanostructures have attracted attention for their use as catalyst. A large class of mixed valence metal oxides crystallizes in spinel structure with a general formula of AB2O4, where, for the most spinels, A and B are di- and trivalent cations (2–3 spinels), respectively. Zinc manganite (ZnMn2O4) is known as the most attractive spinel due to its low potential of oxidation and low material cost. ZnMn2O4 is often used in lithium ion batteries because of environmental friendliness, low cost and much lower operating voltage [3,4]. In this work, ZnMn2O4 tetragonal-spinel nanoparticles was used as efficient heterogeneous catalyst. Henceforth, 1,8-dioxo-octahydroxanthene derivatives were synthesized via solvent free multi-component reactions. 2 mmol dimedone and 1mmol benzaldehyde were used as starting materials (Scheme 1). This method provides several advantages such as environment friendliness, high yields and simple work-up procedure. The molecular structure of products has been determined by IR, 1HNMR, and 13CNMR techniques.