tert-Butyl (3S)-3-(piperazin-1-ylmethyl)piperidine-1-carboxylate (3.5 g) and phenyl isocyanate (1.62 g) were stirred in toluene (50 ml) at room temperature for 20 h. The solvent was then concentrated in-vacuo to afford a white solid. The solid was dissolved in methanol and passed through an SCX2 column. The SCX2 column was then flushed with 5% ammonia in methanol solution. The solution was collected and the solvent removed under reduced pressure. The resultant solid was re-crystallised from EtOAc and isoHexane, to afford the desired product as a white solid (4 g).
