To a solution of methylamine hydrochloride (76 mg) in toluene (2 mL) is added a 2N solution of trimethylaluminum in toluene. The reaction mixture is heated at 60° C. for 1 hour. Then a solution of {3-[(benzothiazol-2-yl)(1-methylpiperidin-4-yloxy)-methyl]phenylsulfanyl}acetic acid methyl ester (50 mg) in toluene (1 mL) is added. The reaction mixture is heated at 60° C. for 24 hours. Water is added to the reaction mixture, pH is adjusted to 10 with a solution of sodium hydroxide, and the mixture is filtered on celite. The filtrate is extracted with ethyl acetate. The pooled organic extracts are dried over magnesium sulfate and concentrated under reduced pressure. The residue is purified by chromatography (toluene/acetone/triethylamine 80/20/0.2) to give 2-{3-[benzothiazol-2-yl(1-methylpiperidin-4-yloxy)methyl]phenylsulfanyl}-N-methylacetamide.
