EN
In this report, a rapid, efficient and environmental friendly synthesis of 3-carboxycoumarins under ultrasound irradiation in water media is described. The Knoevenagel condensation of Meldrum’s acid with substituted benzaldehydes in the presence of zirconium oxide chloride (ZrOCl2·8H2O) and ultrasonic irradiation in water gave the corresponding 3-carboxycoumarins in good to excellent yields. [...]