GENERAL STEPS: Potassium carbonate (6.53 g, 47.2 mmol) and iodomethane (0.976 mL, 15.7 mmol) were sequentially added to a solution of N,N-dimethylformamide (45 mL) of 1-diphenylmethylazetidine-3-carboxylic acid (4.20 g, 15.7 mmol) and the reaction was stirred at room temperature for 20.5 hours. After completion of the reaction, the reaction mixture was slowly poured into ice water and extracted with ethyl acetate (3 × 50 mL). The organic layers were combined, washed with saturated saline (50 mL) and dried over anhydrous sodium sulfate. The solvent was removed by concentration under reduced pressure and the resulting crude product was purified by silica gel column chromatography (elution gradient: heptane/ethyl acetate = 5:1 to 3:1). The fraction containing the target compound was collected and concentrated under reduced pressure to give methyl 1-diphenylmethylazetidine-3-carboxylate (3.57 g, 80.8% yield) as yellow crystals.1H NMR (400 MHz, CDCl3) δ: 3.26 (m, 2H), 3.31 (m, 1H), 3.44 (m, 2H), 3.69 (s, 3H), 4.38 (s, 1H), 7.16-7.16-7.16 1H), 7.16-7.20 (m, 2H), 7.25-7.28 (m, 4H), 7.39-7.41 (m, 4H). ESI-MS m/z: 282 [M + H]+.
