Cyclization of aryl enones by SiO₂-H₃ PO₄ catalyst under microwave irradiation: Solvent-free synthesis of some oxazine-2-amine derivatives

A series of some 1, 3-oxazine-2- amine derivatives were synthesised by SiO₂-H₃ PO₄ catalyzed solvent-free cyclization of aryl enones and urea under microwave irradiation and more than 85% yield of the oxazines were obtained. The synthesised oxazine amines were characterized by their physical constants, analytical and spectroscopic data. This synthetic methodology offered environmentally benign reaction, non-hazardousness, pollution free environment, easy work up procedure, technique, shorter reaction time and better yields