Melamine Trisulfonic Acid as a New, Efficient and Reusable Catalyst for the Solvent Free Synthesis of Coumarins

Melamine trisulfonic acid (MTSA) is easily prepared by the reaction between melamine and neat chlorosulfonic acid at room temperature. This compound can be used as an efficient and recyclable catalyst for the synthesis of coumarins via von Pechmann condensation reaction under solvent-free conditions.