Zn(Proline)2: a novel catalyst for the synthesis of dicoumarols

Abstract

A novel, greener approach was adopted for the synthesis of dicoumarols (3a–j) using Zn(Proline)₂ as a mild, non-toxic, Lewis acid catalyst in water employing 4-hydroxycoumarin (1) and aromatic/heteroaromatic aldehydes (2a–j). The catalytic activity results suggest that the methodology adopted offers several advantages such as mild reaction conditions, low loading of catalyst, quantitative yields, short reaction time and operational simplicity.