Two novel classes of 4-aminopiperidines substituted in the 3-position by groups bearing either a carbamate or a ureido function have been synthesized from ethyl 4-oxo-3-piperidinecarboxylate and 3,3′-iminobis(propanenitrile), respectively. The key step in this synthesis, the reduction of the piperidinic β-enamino ester or nitrile, occurred readily. In contrast to published works, the free primary amines