(3-Oxo-[1,2,4]triazolidin-1-yl)bis (butane-1-sulfonic acid) functionalized magnetic -Fe2O3 nanoparticles: A novel and heterogeneous nanocatalyst for one-pot and efficient four-component synthesis of novel spiro[indeno[1,2-b]quinoxaline derivatives

The efficient synthesis of novel spiro[indeno[1,2-b]quinoxaline derivatives via the four-component condensation of amines, ninhydrin, isatoic anhydride, and -phenylenediamine derivatives catalyzed by (3-oxo-[1,2,4]triazolidin-1-yl)bis (butane-1-sulfonic acid) supported on -Fe2O3 as novel heterogenous magnetic nanocatalyst was described. The novel nanocatalyst was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometry (VSM), Field Emission Scanning Electron Microscopy (FE-SEM), and thermal analysis (TGA-DTG). The nanoparticles covered by (3-oxo-[1,2,4]triazolidin-1-yl)bis (butane-1-sulfonic acid) showed enhanced catalytic performance in the preparation of spiro[indeno[1,2-b]quinoxaline derivatives in excellent yields. Moreover, this method showed several advantages such as mild conditions, high yields, easy work-up, and being environmentally friendly. The catalyst can be easily separated from the reaction mixture by an external magnet, recycled, and reused several times without a noticeable decrease in catalytic activity.