Metal and solvent free direct C3-alkylation of 4-hydroxycoumarins with styrene

C3-alkylation of 4-hydroxycoumarins using various styrene in the presence of boron trifluoride diethyl etherate (BF3·Et2O) without any solvent and under 80 °C temperature. This efficient metal-free catalyzed method involves very good yields of the products.