Choline Chloride-Oxalic Acid as a Deep Eutectic Solvent Promoted Synthesis of Aroylamido Coumarin Derivatives in Excellent Yields

An efficient and green protocol for synthesis of title compounds has been achieved via a one pot, three component reaction of 4-hydroxycoumarin or 4-hydroxy-6-methylpyran-1-one, aryl glyoxals and amides in choline chloride/oxalic acid as a deep eutectic solvent (DES) has been described. The DES  system  offers  advantages  in  terms  of  environmentally  benign,  biodegradable,  short  reaction times, high yield and the use of safe and inexpensive components. DES can be easily recovered and can be reused for other runs without any reduction in the activity.