A dendrimer with a trimesoyl core was successfully grafted to the surface of magnetic Fe3O4@SiO2 nanoparticles using a layer-by-layer fabrication technique, resulting in the nanostructure Fe3O4@SiO2@TMD-G2. The modified nanoparticle structure was confirmed through various analytical methods, indicating the successful modification of magnetic nanoparticles with dendron molecules. The Fe3O4@SiO2@TMD-G2 nanocatalyst exhibited high catalytic efficiency in the synthesis of biologically important 2-amino-4H-benzopyran derivatives and novel azo-functionalized 2-amino-5-hydroxy- 4H-chromene-3-carbonitrile derivatives under environmentally friendly conditions. The use of 7 mg of catalyst at 70 °C in an ethanol–water mixture resulted in the highest yield of the desired products (83%–96%), without any byproduct formation. The presence of electron-withdrawing groups on the aldehyde starting material typically accelerates the reaction. The nanocatalyst heterogeneity was evaluated through a hot filtration experiment. This approach offers advantages, such as reduced reaction times, the use of eco-friendly solvents, and easy catalyst recovery using a magnetic field. The catalyst also showed excellent magnetic recyclability, maintaining its performance over five consecutive reaction cycles. This process is aligning with green chemistry principles, highlighting its economic viability and environmental sustainability.
