152305-23-2

726134-79-8

105-58-8

152305-23-2

General steps: 1. (S)-2-Amino-3-(4-aminophenyl)propanol (7.6 kg), diethyl carbonate (13.5 kg) and potassium carbonate (0.633 kg) were added to a reactor and reacted at 135°C. 2. Ethanol was distilled from the reaction mixture within 2.5 hrs. 3. After completion of the reaction, the reaction mixture was cooled to room temperature, methanol (35.0 kg) was added, the salt was removed by filtration through a filter aid and washed with methanol. 4. The methanol in the filtrate was completely distilled under vacuum and isopropanol (9.5 kg) was added to the residue. 5. the product was filtered through a filter aid and washed with isopropanol to give (S)-4-(4-aminobenzyl)-1,3-azolidin-2-one. 6. The product was dried under vacuum at 50 °C to give 6.85 kg (76.7% yield, melting point 95-100 °C). 7. The product was analyzed: molecular formula C10H12N2O2, molecular weight 192.0; IR spectrum (KBr): lactone peak 1759 cm-1; 1H NMR and 13C NMR were consistent with the expected structure. Note: Step B is the preparation of (S)-4-(4-aminobenzyl)-2-oxazolidinone, the specific operation is similar to that of Step A. Dimethyl carbonate was used instead of diethyl carbonate, and the reaction temperature was 115-120 ℃, and other conditions were the same.