Synthesis of enantiopure aminonaphthol derivatives under conventional/ultrasonic technique and their ring-closure reaction

New optically active aminoalkylnaphthols were obtained by condensation of 2-naphthol, substituted aromatic and heteroaromatic aldehydes and (R)-(+)-1-phenylethylamine or (S)-(−)-1-phenylethylamine under conventional methods and ultrasonic irradiation. The enantiopure aminoalkylnaphthol derivatives were converted in ring-closure reaction with formaldehyde to the corresponding naphthoxazine derivatives.