Benzoyl chloride → N-[(3,4-dimethoxyphenyl)methyl]benzamide

To a mixture of 3,4-dimethoxybenzylamine (24.0 g, 0.144 mol), tetrahydrofuran (192 mL) and triethylamine (15.5 g, 0.153 mol) was added dropwise benzoyl chloride (20.7 g, 0.147 mol) at −7-0° C. During addition dropwise, tetrahydrofuran (24 mL) was added thereto to stir the mixture. After adding dropwise, the dropping funnel was washed with tetrahydrofuran (12 mL), and tetrahydrofuran (24 mL) was added again thereto. The reaction mixture was gradually warmed to about 15° C. The reaction was monitored by TLC (eluent: hexane/ethyl acetate (1:1)). To the reaction mixture was added water (48 mL) at 5-8° C., and then added ethyl acetate (144 mL). The organic layer was separated, and the aqueous layer was extracted with ethyl acetate (48 mL×2). The combined organic layers were washed successively with 10% hydrochloric acid (48 mL), saturated aqueous sodium hydrogen carbonate solution (48 mL), water (48 mL) and saturated brine (48 mL), and dried over magnesium sulfate (12 g), and the solvent was evaporated under reduced pressure at 40° C. or lower. To the concentrate (40 g) was added ethyl acetate (89 g), and the mixture was homogenized with warming at 50° C., and cooled to 11° C. The solid was collected by filtration, washed with cold ethyl acetate (15 mL), and dried under reduced pressure at 40° C. or lower to give N-benzoyl-3,4-dimethoxybenzylamine (33.3 g, 85.4%) as white crystals.