Synthesis of Benzopyrano[2,3-d]pyrimidines Using Silica-Bonded N-Propyldiethylenetriamine Sulfamic Acid (SPDTSA) As Heterogeneous Solid Acid Catalyst under Solvent-Free Conditions

Abstract

Silica-bonded <em>N</em>-propyldiethylenetriamine sulfamic acid (SPDTSA) is employed as a recyclable heterogeneous solid acid catalyst for the synthesis of benzopyrano[2,3-<em>d</em>]pyrimidines through one-pot condensation reaction of salicylaldehydes, malononitrile and secondary amines at room temperature under solvent-free conditions. SPDTSA showed much the same efficiency when used in consecutive reaction runs.