A Simple and Convenient Method for the Synthesis of Pyrano[3,2-c] chromenes via Sequential Three Component Reaction

Background: Pyrano[3,2-c]chromenes are important frameworks of various natural products and have attracted much attention due to their biological activities. These properties include spasmolytic, anti microbial, anti coagulant, anti tumor and central nervous system activities. Methods: we described a convenient method for the preparation of functionalized pyrano[3,2-c] chromenes from the reaction of malononitrile, activated alkynes and 4-hydroxycoumarin in the presence of Et3N in EtOH at reflux condition. Result: Five pyrano[3,2-c]chromene derivatives were synthesized in high yield and their structures were completely characterized by spectroscopic techniques and elemental analysis. These products have potential applications in medicinal chemistry and in organic synthesis. Conclusion: A practical procedure one pot, three component reaction of readily available starting materials to give pyrano[3,2-c]chromene compounds has been developed. This method has some advantages like mild reaction condition, experimental simplicity, easy purification of products and does not require any metal-catalyst.