To a solution of tetrahydrofuran (THF, 50 mL) of tert-butyl 3-hydroxy-azetidine-1-carboxylate (0.8 g, 4.62 mmol) was added sodium hydride (60% dispersed in mineral oil, 0.74 g, 18.5 mmol). The reaction mixture was stirred at 0 °C for 0.5 h, followed by the slow addition of iodomethane (2.8 mL, 46.2 mmol). The reaction mixture was stirred overnight at room temperature. After completion of the reaction, it was quenched with water (50 mL) and extracted with ethyl acetate (EtOAc, 30 mL x 3). The organic phases were combined, dried with anhydrous sodium sulfate (Na2SO4), filtered and concentrated under reduced pressure to afford the target product 3-methoxy-N-Boc-azetidine (0.8 g, 93% yield) as an oil.1H NMR (400 MHz, CDCl3): δ 4.11-4.13 (m, 1H), 4.04-4.08 (m, 2H), 3.79- 3.83 (m, 2H), 3.27 (s, 3H), 1.43 (s, 9H).
