Dual role of ammonium acetate for solvent-free synthesis of 1,3-disubstituted-2,3-dihydro-1H-naphth-[1,2e] [1,3]-oxazine

Ammonium acetate plays a dual role for the solvent-free synthesis of 1,3-oxazine under neat heating at 60°C and under microwave irradiation with excellent yields. The synthetic strategy involved the formation of a Betti base which upon condensation with aromatic aldehydes gives the preferred oxazine ring. The present protocol contributes remarkable advantages, such as solvent- and catalyst-free reaction conditions, simple work-up procedures, shorter reaction times, and environmentally benign methodology.