Tris(2-hydroxyethyl)ammonium lactate an effective and biodegradable catalyst for the preparation of 3,4-dihydropyrano[c]chromene derivatives.

A protocol for the synthesis of 3,4-dihydropyrano[c]chromenes (DHPCs) using tris(2-hydroxyethyl)ammonium lactate (THAL) as an ionic liquid (IL) and biodegradable catalyst has been developed. This method involves the reaction of aldehydes, malononitrile, and 4-hydroxycoumarin under solvent-free conditions at 80 °C. The efficiency of THAL as catalyst was evaluated by conducting a series of control experiments using dimedone, 2-hydroxynaphthalene-1,4-dione, and 1,3-dimethylbarbituric acid as substrates under optimized conditions. [ABSTRACT FROM AUTHOR]