Synthesis, electronic structure, and absorption spectra of 9-hydroxypyrido[1,2-a]-pyrimidinium derivatives

Pyrido[1,2-a]pyrimidinium salt derivatives have been prepared by condensation of 2-aminopyridinium salts with Β-dicarbonyl compounds. The acid-base equilibrium dissociation constants for 2,4-dimethyl-9-hydroxypyrido[1,2-a]pyrimidinium perchlorate have been measured, and the spectroscopic characteristics of its neutral, anionic, and cationic forms have been determined; the electronic absorption spectra of the neutral and anionic forms of 2,4-dimethyl-9-hydroxypyrido[1,2-a]-pyrimidinium perchlorate have been interpreted based on this experimental and calculated data. © 1992 Plenum Publishing Corporation.