1-[1-(4-Hydroxyiminomethylphenethyl)piperidin-4-yl]indoline (2.71 g) was dissolved in tetrahydrofuran (40 ml). Under ice cooling, lithium aluminum hydride (0.59 g) was added thereto and the resultant mixture was heated under reflux for 2 hr. Then the reaction mixture was ice cooled again followed by the addition of water (0.6 ml), a 5 N aqueous solution (0.6 ml) of sodium hydroxide and further water (1.8 ml) thereto. The resulting precipitate was filtered off and the filtrate was washed with ethyl acetate and concentrated under reduced pressure to give the title compound (1.462 g) as a pale yellow oil (yield: 56.2%).
