Anchoring of ruthenium onto imine-functionalized zeolite beta: an efficient route for the synthesis of 4H-benzo[b]pyrans and pyrano[c]chromenes

The synthesis and characterization of a highly efficient and reusable catalyst, ruthenium immobilized in zeolite beta, are reported. The catalyst was characterized by powder X-ray diffraction, BET surface area measurements, scanning electron micrographs, Fourier-transform infrared spectroscopy, inductive coupled plasma, and elemental analysis. The supported material was used as an efficient catalyst for the one-pot three-component synthesis of 4H-benzo[b]pyrans and pyrano[c]chromenes in good yields. The catalyst was separated from the reaction mixture and reused up to five runs without significant loss of activity.