A green eco approach toward the synthesis of novel 4-iminoquinoline derivatives using Brønsted acid nanocatalysts

A series of novel 4-iminoquinolines were synthesized from the reaction of 2-aminobenzonitrile, orthoesters, and active methylenes in the presence of Brønsted acid nanocatalysts (Fe₃O₄@APTES-MAH NPs or VSA NRs) under solvent-free conditions. VSA NRs were prepared by the reaction of the chlorosulfonic acid and sodium monovanadate at high purity. The amine-surfaced Fe₃O₄@APTES NPs prepared using the coating of Fe₃O₄ nanoparticles with 3-aminopropyltriethoxysilane were further modified with maleic anhydride to produce Fe₃O₄@APTES-MAH NPs. The reaction is characterized by high yields, simple purification of the products, inexpensive, short reaction times, reusability, and stability of the catalysts. Graphical abstract: .