Silica-bonded N-Propyl Sulfamic Acid: A Recyclable Catalyst for the Synthesis of 1,8-Dioxo-decahydroacridines, 1,8-Dioxo-octahydroxanthenes and Quinoxalines

Silica bonded N-propyl sulfamic acid (SBNPSA) is employed as a solid acid catalyst for the synthesis of 1,8-dioxo-decahydroacridines and 1,8-dioxo-octahydroxanthenes in high yields and short reaction times in ethanol under reflux conditions. Also, this solid acid catalyzed the reaction of 1,2-diamino compounds with 1,2-dicarbonyl compounds for the synthesis of quinoxaline derivatives at room temperature. The catalyst could be recycled and reused several times without any loss of efficiency.