To a suspension of 4-{(R)-2-[4-(4-chloro-phenyoxy)-phenoxymethyl]-pyrrolidin-1-yl}-butyric acid HCl salt (220 mg, 0.5 mmol, 1 eq.) in dichloromethane (5 ml) was added PyBrOP (280 mg, 0.6 mmol, 1.2 eq.), DIPEA (200 mg, 1.5 mmol, 3 eq.) and (R)-1-phenyl ethylamine (80 mg, 0.6 mmol 1.2 eq.). The mixture was stirred at room temperature overnight. The volatile material was removed under reduced pressure and the residue was purified by preparative TLC using dichloromethane/MeOH (15:1) as mobile phase (twice) followed by a column chromatography on silica gel using dichloromethane/MeOH (15:1) as eluent to give the desired product (12 mg, 5%); LCMS (UV, ESI), m/z 493 (M); HPLC: 99%.
