Starch–Mn complex supported on Fe₃O₄ as a magnetically recyclable catalyst for Tetrazole synthesis via Homoselective [3 + 2] cycloaddition reactions

This study details the synthesis of a novel, magnetically separable polysaccharides manganese complex. The complex was prepared via a simple and efficient three-step procedure involving the surface functionalization of Fe₃O₄ with starch, which acts as a ligand and linker, followed by complexation with manganese acetate. This process utilizes green reagents and conditions. The resulting magnetic nanocomposite was then applied as a catalyst in the [3 + 2] cycloaddition reaction of aryl nitriles with sodium azide in PEG-400, a green solvent, to yield 5-substituted-1H-tetrazoles in good to excellent yields (85–98 % yields) within short reaction times (20–110 min). The Fe₃O₄@Starch-Mn catalyst demonstrated high catalytic efficiency, retaining 98 % of its initial activity after six reuse cycles and 93 % after twelve cycles. The catalyst's magnetic separability, reusability, stability, and the use of inexpensive, environmentally friendly materials for its preparation and reaction conditions highlight the advantages of this approach.