To a solution of (3S,6R)-6-methyl-1-{[(phenylmethyl)oxy]carbonyl}-3-piperidinecarboxylic acid (17 g, 61.3 mmol) in DMF (400 mL) was added aniline (8.56 g, 92 mmol), Hunig's base (32.1 mL, 184 mmol), HOBt (14.08 g, 92 mmol) and EDC (17.63 g, 92 mmol) at room temperature. The reaction mixture was stirred overnight at room temperature, then diluted with H2O (˜100 mL), and extracted with EtOAc (3×250 mL). The combined organic layers were washed with 1N HCl (100 mL), H2O (3×100 mL), brine (100 mL), dried (MgSO4), filtered and concentrated in vacuo to afford the crude title compound (21 g). LC-MS (ES) m/z=353 [M+H]+.
