General procedure for the synthesis of 3-aminooxazolidin-2-one from 2-hydrazinoethanol and diethyl carbonate: 15.2 g (0.2 mol) of 2-hydrazinoethanol (Intermediate 1), 31.0 g (0.2 mol) of diethyl carbonate, and 3.0 g (57 mmol) of sodium methanol were added to a 100 mL three-necked flask, and the mixture was heated and refluxed for 4 hours. Upon completion of the reaction, the reaction mixture was cooled and a solid was precipitated. The solid was collected by vacuum filtration and dried. The solvent in the mother liquor was removed by distillation. The crude product was purified by column chromatography (eluent: methanol/dichloromethane, 1:20, v/v), and the resulting white solid was recrystallized in ethanol to give 15.3 g of 3-aminooxazolidin-2-one (Intermediate 2) in 75% yield. The product was characterized as follows: 1H-NMR (400 MHz, D2O) δ ppm: 4.33 (2H, t, J = 8.0 Hz), 3.94 (2H, s), 3.70 (2H, t, J = 4.0 Hz); EI-MS (m/z): 103.1 [M + H]+; Melting point: 64-66 °C.
