To a solution of (±)-methanesulfonic acid 2-[(2-benzyloxy-5-fluoro-phenyl)-methanesulfonyloxy-methyl]-benzyl ester (650 mg, 1.31 mmol, 1.0 eq.) in DMF (15 mL), benzylamine (0.19 mL, 1.71 mmol, 1.3 eq.) and DIPEA (0.69 mL, 3.94 mmol, 3.0 eq.) were added in sequence. The mixture was heated at 70° C. for 2 days. The reaction mixture was allowed to cool to r.t. and concentrated in vacuo. The residue was filtered and then purified by prep. HPLC (column: Water X-Bridge, 30×75 mm, 10 um, UV/MS, basic conditions) and concentrated in vacuo to give (±)-2-benzyl-1-(2-benzyloxy-5-fluoro-phenyl)-2,3-dihydro-1H-isoindole.
