To a solution of 7-[4-(4-benzo[b]thiophen-4-ylpiperazin-1-yl)butoxy]-3,4-dihydro-1H-quinolin-2-one (0.3 g) synthesized in the same manner as in WO2006/112464 (Example 11) in methylene chloride (10 ml) was added pyridine (0.11 ml), with stirring under ice-cooling, dodecanoylchloride (0.24 ml) was added, and the mixture was stirred at room temperature overnight. Water was added to the reaction mixture and the mixture was extracted with methylene chloride, and dried over sodium sulfate. The solvent was evaporated under reduced to pressure and the residue was purified by silica gel column chromatography (ethyl acetate) to give 7-[4-(4-benzo[b]thiophen-4-ylpiperazin-1-yl)butoxy]-1-dodecanoyl-3,4-dihydro-1H-quinolin-2-one (0.4 g).
