Conc. sulfuric acid (0.185 ml ) was added to a mixture of 2-amino-4,5,3',4'-tetramethoxybenzophenone (10.0 g), acetylacetone (3.78 g) and acetic acid (75 ml), and the mixture was stirred at 100° C. for 2.5 hours. The reaction mixture was concentrated under reduced pressure. The residue was poured into water and made alkaline with 2N sodium hydroxide, and extracted with chloroform. The chloroform layer was washed with water and dried over magnesium sulfate, and the solvent was evaporated under reduced pressure. The residue was subjected to column chromatography on silica gel. The fractions eluted with chloroform-ethanol (20:1, v/v) gave 3-acetyl-4-(3,4-dimethoxyphenyl )-6,7-dimethoxy-2-methyl-quinoline (9.78 g, 82%). This compound was recrystallized from dichloromethane-ethanol to give colorless prisms, mp. 210°-211° C.
