Chapter 3 Pyridine and Piperidine Alkaloids

The designation of pyridine and piperidine alkaloids as a group introduces a level of arbitrariness. These compounds do not stem from a common biosynthetic precursor, they are not unique to a single taxonomic family, and even the structural characteristics that might seem to define the group are open to interpretation. However, the historical recognition of these alkaloids as a class, and the practice of reviewing them as such are sufficient reasons to continue these traditions. This chapter represents a survey of the relevant literature on pyridine and piperidine alkaloids. It includes alkaloids containing a piperidine-type nitrogen heterocycle (at any oxidation level) that is not fused to a carbocyclic system. Alkaloids in which the nitrogen-containing ring is fused to a second heterocycle, such as gentianine have in some cases been included, except where such fusion generates another readily identifiable heterocyclic moiety, such as the quinolizidine system. The alkaloids are grouped in sections, largely on the basis of their structural characteristics, although biogenetic or taxonomic considerations have also been taken into account in some instances.