BOP (880 mg, 2.0 mmol) was added to a mixture containing pyrrolidine (142 mg, 2.0 mmol), Et3N (279 ul, 2.0 mmol) and N-Boc-2-phenylalanine (570 mg, 1.67 mmol) in DMF (10 ml) and the resulting mixture was stirred at room temperature for 16 h. The solvent was removed under reduced pressure and the residue was taken up in EtOAc and washed with brine, dried and concentrated. The crude product was purified by column chromatography (48 g silica gel 60, 230-400 mesh, 20% EtOAc in hexane as eluent) to give 581 mg (75%) of the title compound as a white solid. MS (ES) m/e 395.6 [M+H]+
