A highly efficient and fast method for the synthesis of biscoumarins using tetrabutylammonium hexatungstate [TBA] 2[W 6O 19] as green and reusable heterogeneous catalyst

Abstract

A novel catalytic synthesis of biscoumarins from 4-hydroxycoumarin and aromatic aldehydes has been developed. The reaction occurs in ethanol in the presence of tetrabutylammonium hexatungstate [TBA] 2[W 6O 19] as catalyst to give the corresponding products in high yields. This new approach has short reaction times, clean reaction profiles, and simple experimental and workup procedures. Moreover, the catalyst can be easily recovered by filtration and used at least three times with only slight reduction in its catalytic activity.