A Mild and Green Route for Regio-selective Amination of Oxiranes Using Nanomagnetic Supported Ferrous Ion as a Solid Lewis Acid Catalyst in Water

A mild, green and highly efficient route for regio-selective amination of oxiranes was developed via incorporation of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) cations onto the surface of hydroxyapatite-encapsulated γ-Fe2O3 nanoparticles (γ-Fe2O3@HAp). Among six magnetically recoverable catalytic systems denoted as [γ-Fe2O3@HAp-MII], the catalyst in which M designated as Fe(II) showed the best efficiency as well as regio-selectivity in amination of oxiranes under an ambient reaction condition. A wide variety of aromatic and aliphatic amines were reacted with epoxides using magnetically separable iron catalyst to give the corresponding amino alcohols in excellent yields and selectivities in water as solvent at room temperature. In addition, recovery of the catalyst was successfully carried out in subsequent runs without any decrease in activity even after 5 runs. High regio-selectivity toward terminal ring-opening, efficient catalyst reusability using simple magnetic separation, high yields, simplicity in operation and diversity for various substrates are of advantages of this study.