A solution of 1-(3-fluoro-4-methoxyphenyl)-5-oxopyrrolidine-3-carboxylic acid (1.5 g, 5.92 mmol), BnOH (1.92 g, 17.76 mmol), Et3N (1.24 mL, 8.88 mmol) and DPPA (1.84 g, 7.12 mmol) in 100 mL of toluene was heated to 120° C. for 6 h. The reaction was cooled to RT and concentrated in vacuo. The residue was purified by chromatography on a silica gel column (10% to 70% EtOAC/hexane) to give the title compound as colorless crystal. MS (ESI pos. ion) m/z: 359.4 (M+H). Calc'd Exact Mass for C19H19FN2O4: 358.36.
