Core-Shell Fe3O4@SiO2-SO3H Nanoparticles as Efficient Catalyst in the Synthesis of Dihydropyrano [3,2-c]chromenes

Pyrano[3,2-c]chromenes have received considerable attention in medical chemistry due totheir unique biological and pharmacological properties. They exhibite biological activitiessuch as anticancer, anti-inflammatory, antimicrobial, and antihyperglycemic activities. [1-3]Paying attention to green chemistry concept efforts are conducted to use less toxic chemicalsand less organic solvents in synthetic chemistry. Therefore, one pot multi-component reactionsare receiving more attention as an alternative for multi-step reactions. The synthesis ofpyrano[3,2-c]chromenes via multicomponent requires long reaction time while giving moderateproduction yields. However, employing a proper catalyst may boost the yield in shorterreaction time.In the current research paramagnetic core-shell nanoparticles of Fe3O4@SiO2 and sulfuricacid-functionalized one (Fe3O4@SiO2-SO3H) were synthesized and characterized by FT-IR,XRD, and SEM. [2,3] They have been employed as catalysts in one pot synthesis ofdihydropyrano[3,2-c]chromenes via reaction of 4-hydroxycoumarin, malononitrile and a widerange of functionally substituted benzaldehydes. Catalyst Fe3O4@SiO2-SO3H which showedhigher activity was separated from the reaction mixture and reused for three times withoutloss in its catalytic activity.