Facile and Efficient Synthesis of 9-Aryl-1,8-Dioxo-Octahydroxanthenes Catalyzed by Sulfacetamide

In this study, the domino Knoevenagel-Michael and cyclization reaction between 5,5-dimethyl-1,3-cyclohexanedione (dimedone) and aryl aldehydes was performed in the presence of sulfacetamide as an organocatalyst in refluxing ethanol for the synthesis of 3,3,6,6-tetramethyl-9-aryl-1,8-dioxo-octahydroxanthene derivatives. This organocatalyzed reaction proceeds through the formation of 2,2 '-[(4-(aryl)phenyl)methylene]bis[3-hydroxy-5,5-dimethylcyclohex-2-en-1-one] intermediates, leading to the construction of final oxygen-containing heterocyclic compounds. Considering the loading of the organocatalyst and the study of the effects of the solvent, it can be concluded that 2 mol% of catalyst and ethanol are the best choice to run the pseudo-three-component reaction. Furthermore, the pot-economy, atom-economy, and step-economy reaction follows some principles of green chemistry, such as cost-effectiveness, benign catalyst, and using nontoxic solvent.