One-pot preparation of coumarins by Knoevenagel condensation in solvent-free condition under microwave irradiation

Abstract

3-Substituted coumarins were prepared by the Knoevenagel reaction of 2-hydroxybenzaldehyde derivatives and 2-hydroxy-1-naphthaldehyde in the presence of ammonium aceteate on basic alumina or silica gel under microwave irradiation. High yields, low reaction times, being environmentally friendly, elimination of organic base and solvent are advantages of this method.