Knoevenagel condensations of 1,3-dicarbonyl compounds with aldehydes catalyzed by heterogeneous Ps-AlCl3 without solvents

Abstract

A simple, efficient procedure is proposed for Knoevenagel condensations of 1,3-dicarbonyl compounds with aldehydes catalyzed by heterogeneous polystyrene-supported aluminum chloride (Ps-AlCl₃) under solvent-free conditions. The condensations are carried out smoothly with high yields (87–98%) at 60 °C for 2–4 h in the presence of the Ps-AlCl₃ catalyst. The catalyst is characterized by Fourier transfer-infrared spectroscopy (FT-IR). The catalyst is applicable to a wide range of aldehydes, and has excellent recyclability and can be reused several times without loss of activity.