Synthesis of 3-carboxycoumarins at room temperature in water extract of banana peels

The 3-carboxycoumarin is a major heterocycle in many biologically active agents, including anti-cancer, antibacterial and cosmetics. 3-Carboxycoumarins are also involved in the actions of plant growth hormones and growth regulators. Many catalytic systems have been used for the synthesis of 3-carboxycoumarins but such systems present issues such as harsh reaction conditions, tedious work-up and use of toxic solvents. Therefore, here we tested the synthesis of 3-carboxycoumarins by one-pot Knoevenagel condensation and intramolecular cyclization of various 2-hydroxybenzaldehydes with meldrum's acid, using water extract of banana. Products were obtained in 76-94% yields in 420-490 min at room temperature by simple filtration.