6066-82-6

110-15-6

30364-60-4

General procedure for the synthesis of bis(2,5-dioxopyrrolidin-1-yl) succinic acid esters from N-hydroxybutanediimide and butanedioic acid: to a solution of THF (50 mL) of butanedioic acid (30 g, 254 mmol, 1.0 eq.) was added a solution of THF (50 mL) of N-hydroxybutanediimide (64 g, 556 mmol, 2.2 eq.). A THF (50 mL) solution of N,N'-dicyclohexylcarbodiimide (DCC, 11.5 g, 55.8 mmol, 0.22 eq.) was slowly added dropwise with stirring at 0 °C. After dropwise addition, the reaction mixture was stirred at room temperature overnight. The reaction progress was monitored by liquid chromatography-mass spectrometry (LC-MS). After completion of the reaction, the solid was collected by filtration and the filtrate was concentrated to obtain the crude product. The resulting solid was washed sequentially with THF and ethanol to give the final bis(2,5-dioxopyrrolidin-1-yl) succinate (24 g, 27% yield) as a white solid.