Microwave-Assisted Solvent-Free Rapid Synthesis of 4-Methyl Coumarin Derivatives by Using Silica functionalized-SO3H as an Effective Heterogeneous Catalyst.

A novel silica gel functionalized-SO₃H as a heterogeneous catalyst was prepared and characterized by FT-IR, XRD, TGA and elemental analysis. It has been studied for microwave-assisted solvent-free Pechmann condensation. The result revealed that 20% w/w silica bonded 3-mercapto propyl diethylene diamine N-sulfamic acid (SMPDDSA) was found to be effective. 4-methyl coumarin derivatives were the only product obtained in good to excellent yield (75–94%). The present protocol accomplishes the reaction in much lesser time as compared to the conventional method. [ABSTRACT FROM AUTHOR]