Ethylamine → N-(3,5-bistrifluoromethylbenzyl)-N-ethylamine

In 20 ml of methanol was dissolved 24.5 g of 3,5-bistrifluoromethylbenzaldehyde, and under ice-cooling, added thereto was 60 ml of ethylamine (a 2M tetrahydrofuran solution). Subsequently, 4.38 g of sodium borohydride was slowly added thereto, and the mixture was stirred at room temperature for 3 hours. To the reaction mixture was added distilled water and concentrated under reduced pressure. The residue was extracted with dichloromethane, and the organic layer was dried and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane:ethyl acetate=4:1→chloroform:methanol=9:1), to give 6.35 g of N-(3,5-bistrifluoromethylbenzyl)-N-ethylamine as shown in Table 135 below.