Acetanilide is converted into 2-chloro-3-formyl quinoline by reacting with DMF-POCl3 at 80-90ºC and then condensed with aromatic primary amines to give Schiff bases (3a-3c). These Schiff bases are then reacted with acid chlorides in the presence of base in toluene to give 1, 3, 4-substituted 2-azetidinones

α-Naphthol is converted into 4-methylbenzo[h]chromen-2-one by reacting with ethyl acetoacetate in the presence of bismuth trichloride which is then oxidized to 2-oxo-2H-benzo[h]chromene-4-carbaldehyde and then condensed with aromatic primary amines to give Schiff bases (3a-3d). These Schiff bases are then reacted with acid chlorides in the presence of base in toluene to give 1, 3, 4-substituted 2-azetidinones