18133-18-1

149-87-1

98-80-6

18133-18-1

In a 10 mL round bottom flask, 4 mL of anhydrous acetonitrile, 0.258 g of DL-pyroglutamic acid (2.00 mmol, 1 eq.) and 0.598 mL of 1,8-diazabicyclo[5.4.0]undec-7-ene (4.00 mmol, 2 eq.) were added. After 10 min of reaction, 0.139 g of di-μ-hydroxy-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)] chloride (0.300 mmol, 0.15 eq.) was added; after 20 min, 0.366 g of phenylboronic acid (3.00 mmol, 1.5 eq.) was added. The reaction mixture was stirred at room temperature for 48 hours. After completion of the reaction, the solvent was removed by vacuum evaporation and the residue was dissolved in 30 mL of saturated aqueous NH4Cl solution and washed with ethyl acetate (3 x 20 mL). The aqueous layer was acidified with 3 M HCl aqueous solution and extracted with ethyl acetate (3 x 50 mL). The organic phases were combined, washed with brine (2 × 25 mL) and dried over magnesium sulfate. The solvent was evaporated in vacuum to afford the target product 5-oxo-1-phenylpyrrolidine-2-carboxylic acid (0.349 g, 85% yield) as an off-white powder.