Nano-Fe3O4@walnut shell/Cu(ii) as a highly effective environmentally friendly catalyst for the one-pot pseudo three-component synthesis of 1,3-oxazine derivatives under solvent-free conditions

摘要

Fe _(3) O _(4) @walnut shell/Cu( II ) as an eco-friendly bio-based magnetic nano-catalyst was prepared by adding CuCl _(2) to Fe _(3) O _(4) @walnut shell in alkaline medium. A series of 2-aryl/alkyl-2,3-dihydro-1 H -naphtho[1,2- e ][1,3]oxazines were synthesized by the one-pot pseudo three-component reaction of β-naphthol, formaldehyde and various amines using nano-Fe _(3) O _(4) @walnut shell/Cu( II ) at 60 °C under solvent-free conditions. The catalyst was removed from the reaction mixture by an external magnet and was reusable several times without any considerable loss of its activity. This protocol has several advantages such as excellent yields, short reaction times, clean and convenient procedure, easy work-up and use of an eco-friendly catalyst.