An efficient ZrCl4 catalyzed one-pot solvent free protocol for the synthesis of 4-substituted coumarins

A versatile and efficient route to 4-substituted coumarins via a Pechmann reaction using ZrCl4 as the catalyst (10 mol %) is described. This method provides several advantages over alternative procedures such as mild, solvent-free conditions at ambient temperature, and direct isolation of the products in high yields.