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In the present study, for the first time N-(3-silyl propyl) diethylene triamine N,N',N''-tri-sulfonic acid (SPDETATSA) was grafted on magnetic Fe3-xTixO4 nanoparticles. The structure of the resulted nanoparticles was characterized based on Fourier-transform infrared (FT-IR), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), and vibrating sample magnetometer (VSM) analyses. The results confirmed the successful immobilization of sulfamic acid groups onto the magnetic support. These nanoparticles exhibited high catalytic activity as novel magnetically recyclable acid nanocatalyst in the synthesis of a diverse range of hexahydroquinolines through one-pot tandem reactions in excellent yields. Also, this nanocatalyst performed satisfactory catalytic maintenance of activity for the synthesis of the reaction products after 4 rounds of recycling with no considerable loss of activity. [ABSTRACT FROM AUTHOR]

Novel urea-functionalized silica-coated magnetic core-shell FeTiO 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 1 H-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. [ABSTRACT FROM AUTHOR]

Silica-modified magnetite-polyoxometalates functionalized with sulfamic acid groups as hybrid nanoparticles were prepared by sulfonation of diamine-functionalized propyl group grafted on the magnetic silica-coated Fe3O4nanoparticles. This heterogeneous nanocatalyst was explored to present high catalytic performance for the synthesis of 3,4-dihydropyrimidinones and tetrahydrobenzo[b]pyrans under mild reaction conditions. The properties of this nanocatalyst were characterized by FT- infrared, energy-dispersive X-ray spectrum, scanning electron microscope, X-ray diffraction, X-ray fluorescence and elemental analysis. Easy separation of the nanocatalyst by using an external magnet, recyclability, non-toxicity, versatility and high stability of the catalyst combined with low reaction times and excellent yields make the present protocol very useful and attractive for the synthesis of the titled products. [ABSTRACT FROM AUTHOR]

A novel acidic nanocatalytic system, sulfamic acid-functionalized Fe 3-x Ti x O 4 magnetic nanoparticles (MNPs), were synthesized through one-pot reaction of Fe 3-x Ti x O 4 MNPs with 3-chloropropyltrimethoxysilane and imidazolidine-2,4-dione followed by functionalization with chlorosulfonic acid. The structure of this newly synthesized nanocatalyst was established by several analysis methods including, Fourier-transform infrared (FTIR) and energy-dispersive X-ray (EDX) spectroscopies, transmission (TEM) and scanning (SEM) electron microscopies, thermal gravimetric (TG), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The potential catalytic ability of this nanocatalyst was evaluated in one-pot four-component condensation reaction between aromatic aldehydes, dimedone, alkyl acetoacetates and ammonium acetate in order to synthesis of hexahydroquinoline derivatives. The reactions proceeded smoothly under solvent-free condition offering excellent yields of corresponding hexahydroquinolines successfully. In addition, the fabricated nanocatalyst exhibited excellent reusability up to four subsequent runs. • A novel magnetite nanocatalyst was synthesized based on Fe 3-x Ti x O 4 nanoparticles. • The catalytic activity was evaluated in synthesis of hexahydroquinolines. • The high yields, short reaction time and simple procedure are the advantages of method. • The nanocatalyst exhibited excellent reusability up to four subsequent runs. [ABSTRACT FROM AUTHOR]