Brønsted Acidic Phosphonium Based Ionic Liquid Functionalized SBA-15 [HO3S-PhospIL@SBA-15]: Green, Recyclable, and Efficient Catalyst for the Synthesis of Pyrano[3,2-c]Chromenone Derivatives

: The surface of SBA-15 was modified by diphenylphosphine; then, it was treated with butane sultone and sulfuric acid to obtain Brønsted acid HO3S-phosphonium based ionic liquid functionalized SBA-15 with HSO4- as a counteranion. It efficiently catalyzed synthesis of pyrano[3,2-c]chromenone derivatives through the reaction of 4-hydroxycoumarin and chalcones at 60 °C in water/ethanol. Good yields, mild reaction conditions, and user-friendly procedure are advantages of this method. Also, the catalyst could be easily separated and reused five times without significant reduction of activity.