To a solution (5 ml) of dodecanoic acid 7-[4-(4-benzo[b]thiophen-4-ylpiperazin-1-yl)butoxy]-2-oxo-3,4-dihydro-2H-quinolin-1-ylmethyl ester (150 mg) synthesized in the same manner as in Example 21 in THF was added trifluoroacetic acid (TFA) (0.11 ml), then to a solution (3 ml) of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) (0.27 g) in THF was added, and the mixture was stirred at room temperature for 3 days. To the reaction mixture were added water and sodium carbonate, and the mixture was extracted with dichloromethane, dried over sodium sulfate, and concentrated under reduced pressure. The residue was purified by preparative thin layer chromatography (ethyl acetate) to give the title compound (yield 50 mg, 33.4%) as a brown oil.
