Rapid and Efficient One-Pot Multicomponent Synthesis of Pyrano[3,2-c]chromene Derivatives, Catalyzed by a Deep Eutectic Solvent

A simple, efficient, and eco-friendly method for the construction of pyrano[3,2-c]chromene derivatives, involving a one-pot multicomponent condensation of 3-hydroxycoumarin, various benzaldehydes, and malononitrile, catalyzed by a choline chloride–urea–thiourea deep eutectic solvent (DES) was developed. The method offers several advantages, including short reaction times, mild conditions, a recyclable and biodegradable catalyst, a simple operating procedure, and excellent yields of the target products. The structures of all the synthesized compounds were confirmed by spectral data.