It was proved that the reaction of each of 1-phenethyl-2 (1H)-pyridone, 1-(3, 4-methyl-enedioxyphenethyl)-2 (1H)-pyridone, and 1-(3, 4-dimethoxyphenethyl)-2 (1H)-pyridone with phophoryl chloride gave the corresponding 2-chloropyridinium salt and not the cyclized product in every case. On being treated with dilute aqueous sodium hydroxide solution at a room temperature, these 2-chloropyridinium salts yielded the corresponding pyridones, which had been described as the ring cleavage of benzo [a] quinolizinium salts induced with various basic reagents.
