To a mixture of methyl 4-{[cyclohexyl(3-methylthieno[2,3-b]pyridin-2-yl)methyl]amino}benzoate (975 mg) synthesized above, tetrahydrofuran (10 mL) and ethanol (10 mL) was added 1N aqueous sodium hydroxide solution (10 mL), and the mixture was stirred overnight with heating under reflux, and concentrated under reduced pressure. The residue was dissolved in water (20 mL), 1N hydrochloric acid (10 mL) was added, and the mixture was extracted with ethyl acetate. The extract was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (30-70% ethyl acetate/hexane) to give the title object compound (701 mg, 75%) as a pale-yellow solid.
