Abstract

Betainic pyridinium alkaloids and analogs are members of the four major classes of heterocyclic mesomeric betaines, i.e. conjugated (CMB), cross-conjugated (CCMB), pseudo-cross-conjugated heterocyclic mesomeric betaines (PCCMB), and conjugated Nylides and thus offer the possibility of detailed comparisons of the types of conjugation. The chemistry of these systems is surveyed.

Keywords: mesomeric betaines, alkaloids, 3- hydroxypyridine, pyridin-n-oxide, picolinic acid