Urea-functionalized silica-coated Fe3−x Ti x O4 magnetic nanoparticles: as highly efficient and recyclable heterogeneous nanocatalyst for synthesis of 4H-chromene and 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives

Novel urea-functionalized silica-coated magnetic core–shell Fe3−x Ti x O4 nanoparticles were prepared and fully characterized by different methods such as Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, vibrating sample magnetometer, X-ray diffraction, and thermogravimetric analyses. These magnetic nanoparticles have been explored as highly efficient and recoverable heterogeneous nanocatalyst for one-pot three-component reactions under mild conditions for the synthesis of diverse range of 5-oxo-dihydropyrano[3,2-c]chromenes known as coumarins and 1H-pyrazolo[1,2-b] phthalazine-5,10-diones in high yields. Simple isolation of the products, use of green solvent, and magnetically easy isolation and reusability of the catalyst with no significant loss of activity are the main advantages of the present method.