Step A: Methylamine (15.3 mL, 40% aqueous solution, 177 mmol) was slowly added dropwise to a stirred solution of 3-fluorobenzaldehyde (20.0 g, 161 mmol) in methanol (150 mL) at room temperature. The reaction mixture was cooled to 0 °C after 6 h of continuous stirring at room temperature, followed by batchwise addition of sodium borohydride (6.10 g, 161 mmol). After removal of the cooling bath, the reaction mixture was gradually warmed to room temperature and stirring was continued for 16.5 hours. Upon completion of the reaction, the reaction was quenched with deionized water and carefully acidified with 2N hydrochloric acid. The acidified mixture was extracted with dichloromethane (3 times). The aqueous phase was subsequently alkalized with 6N sodium hydroxide solution and again extracted with dichloromethane (4 times). All organic phase extracts were combined, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure to afford the target product N-methyl-3-fluorobenzylamine (21.51 g, 96% yield) as a clarified oil. Its 1H NMR (300 MHz, CDCl3) data were as follows: δ 7.32 (td, J = 7.5, 1.7 Hz, 1H), 7.28-7.19 (m, 1H), 7.14-6.98 (m, 2H), 3.80 (s, 2H), 2.45 (s, 3H), 1.47 (br s, 1H).
