A novel method for the synthesis of 1-aryl-1,2-dihydro-3H-naphtho[1,2-e][1,3]oxazine-3‑one derivatives employing one-pot three-component reaction of β-naphthol, aromatic aldehydes, and urea using a catalytic amount of guanidine hydrochloride under solvent-free thermal conditions is described. This method provides several advantages like clean and environmentally benign reaction, simple work-up procedure, low cost, easy product separation without need of further purification with column chromatography, shorter reaction times, and high yields.
