Zirconium@guanine@MCM-41 nanoparticles: An efficient heterogeneous mesoporous nanocatalyst for one-pot, multi-component tandem Knoevenagel condensation-Michael addition-cyclization Reactions

MCM-41-supported nanoscale guanine bonded with Zr (IV) was prepared using sol-gel method and characterized by FT-IR, Raman, XRD, BET, TGA, EDX, ICP, AAS, X-Ray mapping, SEM and TEM techniques. This compound was employed as an efficient, chemoselectivity and green heterogeneous catalyst in order to prepare a series of benzo[a]benzo[6,7]chromeno[2,3-c]phenazine and spiro[benzo[a]benzo[6,7]chromeno[2,3-c] phenazine] derivatives by one-pot, four-component domino reaction from the 2-hydroxy-1,4-naphthoquinone, benzene-1,2-diamines, 2-hydroxy-1,4-naphthoquinone and carbonyl compounds in PEG, at 100 degrees C and, also, Bis (pyrazolyl) methane derivatives using aldehydes and 3-Methyl-1-phenyl-5-pyrazolone in ethanol under reflux condition. Results indicated that all products were synthesized in short reaction times and high yields in the ranges 78-99%. The Zr-guanine-MCM-41 can be recycled four runs without any significant loss of its catalytic activity. In addition, the stability of the catalyst was confirmed by metal leaching, heterogeneity tests, SEM and FT-IR techniques.