A mixture comprising of 3-(3-hydroxyisoxazol-5-yl)propanoic acid (40.2 mg, 0.256 mmol), 3,5-dichlorobenzyl 4-(aminomethyl)-2-methylpiperidine-1-carboxylate (step 4) (84.7 mg, 0.128 mmol), Huenig's base (89 μl, 0.511 mmol) and T3P® (50% solution in DMF)(149 μl, 0.256 mmol) in DMF (426 μl) was left stirring at room temperature 18 hours. The resulting mixture was concentrated under pressure and diluted with water. The aqueous solution was extracted with EtOAc and the combined organic extracts were dried over MgSO4, filtered and concentrated under reduced pressure. Further purification was carried out using preparative LC-MS. The resulting product fractions were concentrated under reduced pressure to give an aqueous solution and then extracted with EtOAc. The organic extracts were dried over MgSO4, filtered and concentrated under reduced pressure to afford the title compound.
