N-Ethyl-4-methoxybenzylamine was synthesized as follows: anisaldehyde (15.6 g, 115 mmol) was mixed with ethylamine (2.0 M solution of THF, 87 mL, 174 mmol) in 1,2-dichloroethane (450 mL) under the protection of nitrogen, followed by the addition of glacial acetic acid (10.0 mL, 174 mmol). The reaction mixture was stirred at room temperature for 30 min and then cooled to 0 °C with an ice bath. Sodium triacetoxyborohydride (NaBH(OAc)3, 36.9 g, 174 mmol) was added in batches, after which the reaction mixture was stirred at room temperature overnight. After completion of the reaction, the mixture was concentrated and the residue was diluted with an alkaline solution (10 g NaOH dissolved in 100 mL of water) to a slightly alkaline color. The aqueous layer was extracted with ether and the organic phases were combined, washed sequentially with water and brine, dried and concentrated. The residue was purified by silica gel column chromatography, eluting first with dichloromethane solution containing 5% methanol, then with dichloromethane solution containing 4% triethylamine in 50% methanol, to afford the target product N-ethyl-4-methoxybenzylamine (11.2 g, 59% yield) as an oil.
