To a solution of triethylamine (1.38 mL) and 4-formyl-2-(trifluoromethyl)benzonitrile (593 mg) in DMF (10 mL) was added (5Z)-5-(piperidin-4-ylmethylidene)-4-(prop-2-yn-1-ylamino)-1,3-thiazol-2(5H)-one dihydrochloride (800 mg). The reaction mixture was stirred at room temperature for 1 hr, and sodium triacetoxyborohydride (2.1 g) was added. The reaction mixture was stirred at room temperature for 3 hr, water was added, and the mixture was extracted with ethyl acetate. The extract was washed with water and saturated brine, and dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate/hexane) and recrystallized from ethyl acetate/heptane to give the title compound (250 mg).
