Application of tris (trihexyltetradecylphosphonium) gadolinium hexachloride as magnetically recoverable catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones in solvent-free conditions

Abstract

A Simple and environmentally friendly procedure for the one-pot multi-component synthesis of 3,4-dihydropyrimidin-2(1<em>H</em>)-one derivatives has been developed by one pot three component reaction of various aldehydes, β-dicarbonyl, and urea in the presence of catalytic amount of tris (trihexyltetradecylphosphonium) gadolinium hexachloride [P_6,6,6,14]₃ [GdCl₆] as a solid acid catalyst without any additional organic solvent. The reactions were carried out at 100 °C under solvent-free conditions. The solid magnetic catalyst was prepared by a simple method and readily separated from the reaction media by external magnet and has excellent reusability several cycles without considerable loss of activity. The advantages of this method are low scale catalyst, waste-free, inexpensive catalyst, solvent-free conditions and easy work up, green and efficient synthetic entry to high yield of products (80-92 %) in a high reusability and a short reaction time (20-45 min). This is the first report on for direct use of [P_6,6,6,14]₃ [GdCl₆] as catalyst in organic transformation.