To a solution of 4-(ethylamino)-1,3-thiazol-2(5H)-one (310 mg) and 1-[2,4-bis(trifluoromethyl)benzyl]piperidine-4-carbaldehyde (802 mg) in 2-propanol (10 mL) was added piperidinium acetate (312 mg). The reaction mixture was stirred at 75° C. for 4 hr and concentrated under reduced pressure. Water was added to the residue, and the mixture was extracted with ethyl acetate. The extract was washed with 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 the obtained solid was washed with diisopropyl ether to give the title compound (110 mg).
