A Simple Green Approach to the Synthesis of 2-Amino-5-oxo-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile Derivatives Catalyzed by 3-Hydroxypropanaminium Acetate (HPAA) as a New Ionic Liquid

A new ionic liquid, 3-hydroxypropanaminium acetate (HPAA) [H3N+-CH2-CH2-CH2-OH][CH3COO-], was synthesized for the first time and used as an efficient and recoverable catalyst in the synthesis of 2-amino-5-oxo-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile derivatives by condensing together 4-hydroxycoumarin, aldehydes and malononitrile at room temperature. The catalyst can be reused for four times without noticeable loss of activity.