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.

中文翻译：

---

三(2-羟乙基)乳酸铵是一种有效且可生物降解的催化剂，用于制备3,4-二氢吡喃并[c]色烯衍生物

已经开发出使用三（2-羟乙基）乳酸铵（THAL）作为离子液体（IL）和可生物降解催化剂合成3,4-二氢吡喃并[c]色烯（DHPC）的方案。该方法涉及醛、丙二腈和 4-羟基香豆素在无溶剂条件下在 80 °C 下反应。通过在优化条件下使用双甲酮、2-羟基萘-1,4-二酮和1,3-二甲基巴比妥酸作为底物进行一系列对照实验来评估THAL作为催化剂的效率。