Gum arabic-OPOH as a new natural-based green catalyst for the one-pot pseudo-four-component synthesis of naphtho[1,2-][1,3]oxazines.

Gum arabic-OPOH (GA-OPOH) as a unique natural-based green catalyst was synthesized by the reaction of phosphorus pentoxide with gum arabic. The structure and properties of the catalyst were studied several analysis methods such as FT-IR, MAPPING, EDS, SEM, XRD, and TGA. The efficiency of the above-mentioned catalyst was investigated for the synthesis of naphtho-1,3-oxazines a pseudo-four-component reaction of primary amines, formaldehyde, and 2-naphthol under the solvent-free grinding condition at room temperature using an electrical mortar-heater.

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

FeO@walnut shell/Cu(ii) as an eco-friendly bio-based magnetic nano-catalyst was prepared by adding CuCl to FeO@walnut shell in alkaline medium. A series of 2-aryl/alkyl-2,3-dihydro-1-naphtho[1,2-][1,3]oxazines were synthesized by the one-pot three-component reaction of β-naphthol, formaldehyde and various amines using nano-FeO@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.