An Expeditious and Green Synthesis of 3,3¢-(Arylmethylene)-bis-(4-hydroxycoumarins) Catalyzed by 5-Sulfosalicylic Acid

Abstract

The expeditious synthesis of 3,3¢-(arylmethylene)-bis-(4-hydroxycoumarins) via a three-component domino Knoevenagel-Michael reaction (3CDKMR) of various aldehydes and 4-hydroxycoumarin, catalyzed by 5-sulfosalicylic acid (SA) is explored. The reactions were conducted at 80 °C using water as a green and environmentally benign medium. The method has several advantages such as reusability of reaction medium, the avoidance of hazardous organic solvents, readily available reagents, cost-effectiveness, and good to high yields.