78269-85-9

6066-82-6

20160-60-5

78269-85-9

2-(Trimethylsilyl)ethyl chloroformate (S13) was dissolved in acetonitrile (105 mL) at 0 °C. Subsequently, N-hydroxybutanediimide (5.22 g, 45.4 mmol, 1.30 eq.) and triethylamine (4.59 g, 45.4 mmol, 1.30 eq.; dissolved in 11.0 mL acetonitrile) were added to the solution. The reaction mixture was kept stirred at 0 °C for 16 hours. After completion of the reaction, the mixture was poured into water. The aqueous layer was extracted with ether (6 times). The organic layers were combined and washed sequentially with water (2 times), 1.0 M hydrochloric acid and then with water, followed by drying with magnesium sulfate. The dried organic phase was filtered and concentrated under reduced pressure to give 1-[2-(trimethylmethylsilyl)ethoxycarbonyloxy]pyrrolidine-2,5-dione (S14, 7.72 g, 29.8 mmol, 85% yield in two steps) as a colorless solid.