To 3,5-dichlorobenzyl carbonochloridate (331 mg, 1.380 mmol) and 3-(3-hydroxyisoxazol-5-yl)-N-(piperidin-4-ylmethyl)propanamide (step 2) (200 mg, 0.690 mmol) in DCM (7 ml) was added 2M NaOH solution (6.90 ml, 13.80 mmol) and the mixture stirred vigorously at RT for 16 hrs. The mixture was diluted with EtOAc (50 ml) and acidified with 2M HCl. The organics were dried (MgSO4) and concentrated under reduced pressure. The residue was dissolved in MeOH/EtOAc and dry loaded onto silica (10 g). This was applied to a 12 g silica cartridge, eluting with 1% AcOH/EtOAc. The product fractions were combined and concentrated under reduced pressure and the residue was triturated with diethyl ether to afford 3,5-dichlorobenzyl 4-((3-(3-hydroxyisoxazol-5-yl)propanamido)methyl)piperidine-1-carboxylate as a white solid.
