A mixture of 1-[1-(4-fluorophenethyl)piperidin-4-yl]-6-formylindole (400 mg) obtained in Example 130, methylamine hydrochloride (150 mg), sodium triacetoxyborohydride (480 mg), acetic acid (300 mg) and dichioroethane (10 ml) was stirred at room temperature for 2 days. Then a saturated aqueous solution of sodium bicarbonate and ethyl acetate were added to the reaction mixtures. The organic layer was separated, washed with brine, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The resulting residue was purified by Chromatorex NH-silica gel column chromatography (hexane/ethyl acetate system) to give the title compound (140 mg) as an oil. This oil was crystallized from ethyl acetate by using oxalic acid (34 mg) to give the oxalate (140 mg) of the title compound as a white powder (yield: 27%).
