Poly(4-vinylpyridine)-supported sulfuric acid: an efficient solid acid catalyst for the synthesis of coumarin derivatives under solvent-free conditions

Poly(4-vinylpyridine)-supported sulfuric acid is an efficient catalyst for the Pechmann condensation of acetoacetic esters with phenols, leading to the formation of coumarins in good yields within a few minutes under solvent-free microwave conditions. The catalyst used can be recovered and reused after activation.