Selective and highly efficient synthesis of xanthenedione or tetraketone derivatives catalyzed by ZnO nanorod-decorated graphene oxide

ZnO nanorod-decorated graphene oxide (GO/ZnO), containing Lewis and Bronsted acid centers, was introduced as a selective, highly efficient and recoverable nanocatalyst for the pseudo three-component synthesis of diverse tetraketone or xanthenedione derivatives via condensation of aromatic aldehydes with 1,3-dicarbonyl compounds in short reaction times and good to excellent yields in H2O under refluxing and solvent-free conditions, respectively. Moreover, the GO/ZnO nanocomposite was recovered and reused at least four times without a significant decrease in its activity. Low loading of the catalyst, high to excellent yields, the elimination of any toxic heavy metals or corrosive reagents for modification of the catalyst, simple separation and purification of the products, and the reusability of the catalyst are the most significant advantages of this green protocol.