SnO(2) nanoparticles: A recyclable and heterogeneous catalyst for Pechmann condensation of coumarins and Knoevenagel condensation–Michael addition of biscoumarins

Recyclable SnO(2) nanoparticles catalyze the Pechmann condensation between phenolic alcohols and β-ketoesters at room temperature in ethanol leading to coumarins. Also, in another study the synthesis of biscoumarins catalyzed by SnO(2) nanoparticles in the reaction between 4-hydroxycoumarin and aldehydes under same condition reactions. The corresponding coumarins and biscoumarins were produced efficiently with facility and excellent yields (93–98%). These approaches display the advantages of benign reaction conditions, non-chromatographic purification procedure, appropriate functional group tolerance and valuable process.