Synthesis
1. Ethylenediamine (1.17 mL, 17.42 mmol) and diethyl maleate (3 g, 17.42 mmol) were added to a 50 mL round bottom flask and dissolved in propanol (30 mL). 2. The reaction mixture was stirred at 55 °C for 16 h. 3. Upon completion of the reaction, the solvent was removed under reduced pressure by rotary evaporator. 4. The residue was placed in a vacuum drying chamber and The residue was dried to give the crude ethyl 2-(3-oxopiperazin-2-yl)acetate. 5. The crude product was used directly in the next step of the reaction without further purification. Yield: 3.4 g (quantitative yield).
References
[1] Patent: US2008/312231, 2008, A1. Location in patent: Page/Page column 40
[2] Journal of Heterocyclic Chemistry, 1993, vol. 30, # 1, p. 275 - 276
[3] Journal of Pharmaceutical Sciences, 1990, vol. 79, # 5, p. 447 - 452
