Fe 3 O 4 @silica Sulfonic Acid Nanocomposite as a Magnetically Separable Catalyst for the Synthesis of 2-Arylpyrrolo[2,3,4-kl]Acridin-1(2H)-Ones

The synthesis of a series of 2-arylpyrrolo[2,3,4-kl]acridin-1(2H)-ones, three of which are novel, though a one-pot three-component reaction of dimedone, various anilines, and isatin has been achieved in the presence of magnetite nanoparticles supported silica-sulfonic acid as catalyst under solvent-free conditions at 80 °C. The procedure avoids hazardous reagents/solvents and is more eco-friendly than existing methods. Fe₃O₄@silica-sulfonic acid is shown to be a highly efficient catalyst, and could be readily recovered using a simple external magnet and reused several times without any significant loss in activity. The catalyst was fully characterised by FTIR, SEM, XRD, EDX and VSM.