148644-09-1

Sodium hydride (60%, in mineral oil) (0.74 g, 18.5 mmol) was added to a solution of tert-butyl 3-hydroxy-azacyclobutane-1-carboxylic acid (0.8 g, 4.62 mmol) in THF (50 mL). The solution was stirred at 0 °C for 0.5 h, followed by the addition of methyl iodide (2.8 mL, 46.2 mmol). The reaction mixture was stirred overnight at room temperature. The reaction was quenched with water (50 mL) and extracted with EtOAc (30 mL × 3). The combined organic phases were dried over Na₂SO₄, filtered, and concentrated under vacuum to give compound 1-BOC-3-methoxyazacyclobutane (0.8 g, 93%) as an oil. Concentrated hydrochloric acid (5 mL) was added to a solution of compound 1-BOC-3-methoxyazacyclobutane (0.8 g, 4.29 mmol) in methanol (20 mL). The resulting solution was stirred at 25 °C for 16 h.