Triethanol ammonium lactate: An efficient and reusable catalyst for the preparation of dihydropyrano[c]chromene derivatives

Coumarin and some of its hydroxylated derivatives containing a benzene ring fused with a c-pyrone ring possess important chemical reactivity and are naturally occurring compounds, which exhibit antibacterial, antioxidant, anticancer, and antiallergy activities. They are frequently used as intermediates in the production of dyes and herbicides. Derivatives of 4-hydroxycoumarin have been used successfully as potent warfarin-type anticoagulents (i.e., bromadiolone, brodifacoum, flocoumafen, thioflocoumafen) with low toxicity[1].Ascompared to the first-generation multidosewarfarintypeanticoagulants, these compounds are more potentin rodents and require reduced feeding periods andbaits [2]. A task-specific ionic liquid with a Bronsted acid (Triethanolammonium lactate) were used as an efficient and reusable catalyst for the One-Pot three-component condensation of 4-hydroxycoumarin, aldehydes, and malononitrile (or ethyl cyanoacetate) to approach to dihydropyrano[c]chromene derivatives under solvent-free condensation reaction.