Recent Advances in the Synthesis of Piperidines: Functionalization of Preexisting Ring Systems

The present review focuses on strategies for the construction of piperidines which have appeared in the literature since 2003 through mid-2017. In a preceding chapter (2017AHC191), we summarized synthetic methods involving the construction of the piperidine ring from essentially acyclic starting materials in an intra- or intermolecular manner. The present chapter aims at giving a general overview of decoration or modification of previously generated pyridines or piperidines. The hydrogenation of preformed pyridine or pyridinium rings and introduction of substituents into fully saturated piperidines as well as ring expansion of pyrrolidines to piperidines are the most prevalent methods.