Acetic Anhydride → 2-Acetylhexahydrocyclopenta[c]pyrrol-5(1H)-one

Hexahydro-cyclopenta[c]pyrrol-5-one triflutate 1f (717 mg, 3 mmol) was dissolved in 20 mL of acetonitrile, and acetic anhydride (0.42 mL, 4.5 mmol) and triethylamine (0.98 mL, 9 mmol) were then added to the solution in an ice-water bath. Upon completion of the addition, the reaction mixture was then stirred overnight in an ice-water bath. The solvent was evaporated, and water (50 mL) was then added to the residue. The mixture was extracted with ethyl acetate (50 mL×3). The combined organic extracts were washed with 50 mL of saturated brine, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. The residue was purified by silica gel column chromatography to obtain the title compound 2-acetyl-hexahydro-cyclopenta[c]pyrrol-5-one 5a (0.36 g, yield 72%) as a colorless oil.