[Step 1] 100 mg of 1-acetyl-4-oxo-2-methyl-1,2,3,4-tetrahydroquinoline and 227 mg of 4-acetoxyaniline were dissolved in 3 mL of toluene, and 250 μL of titanium tetrachloride (1.0 M dichloromethane solution) was added to the solution under ice cooling. The mixture was stirred for one hour under ice cooling, and then was stirred for another one hour at room temperature. After completion of the reaction, the reaction liquid was filtered through Celite and was concentrated under reduced pressure. The resulting residue was purified by using silica gel chromatography (chloroform), and thus 50 mg (30%) of 1-acetyl-2-methyl-4-[(4-acetoxyphenyl)imino]-1,2,3,4-tetrahydroquinoline was obtained as a yellow soup-like substance.
