One‐Pot, Multicomponent Synthesis of 1,3‐Oxazin‐One and Evaluation of Their Potential Antioxidant Activities

ABSTRACT The synthesis of 1,3‐oxazines from 2‐naphthol, benzaldehyde, and urea is reported using a simple and efficient microwave‐assisted protocol. SiO 2 ‐ZnCl 2 is employed for the first time to synthesize a library of 10 oxazin‐3‐one compounds, out of which five derivatives are novel. In 30–60 s the products were obtained with simplified work‐up, the yield and purity were enhanced, and the reaction time was reduced with the use of microwave assistance. The synthesized oxazines were characterized and evaluated for their in vitro antioxidant properties. The results demonstrated a significant and effective presence of antioxidant capabilities. The compound 1‐(4‐hydroxy‐3‐methoxyphenyl)‐1,2‐dihydro‐3 H ‐naphtho[1,2‐ e ][1,3]oxazin‐3‐one, containing hydroxy and methoxy groups, revealed superior antioxidant activity.