Dicyclohexylcarbodiimide → 2,5-Dioxopyrrolidin-1-yl 4-bromobenzoate

To 4-bromobenzoic acid (5.00 g, 24.9 mmol, 1.00 equiv) and N-hydroxysuccinimide (3.66 g, 31.8 mmol, 1.28 equiv) in a round-bottom flask in dioxane (120 mL) was added an dioxane solution (30 mL) that contained 1,3-dicyclohexylcarbodiimide (DCC) (6.77 g, 32.8 mmol, 1.32 equiv) dropwise over 5 min at 23 ° C. The reaction mixture was stirring at 23 ° C. for 24 h. The reaction mixture was concentrated in vacuo and the crude product was obtained by recrystallization in a cold acetone. The crude product was further purified by chromatography on silica gel eluting with hexanes/EtOAc 2:1 (v/v) to afford 6.34 g of the title compound as a colorless solid (86%).