Cyclic quaternary ammonium salts. Part V. Pyrido[1,2-a]pyrazin-5-ium salts

Abstract

The synthesis of pyrido[1,2-a]pyrazin-5-ium salts and of 1-hydroxy- and 1,3-dihydroxy-pyrido[1,2-a]pyrazin-5-ium salts is described; the spectroscopic properties of these potentially tautomeric hydroxy-salts indicate that the carbonyl forms are preferred. Bromination of pyrido[1,2-a]pyrazin-5-ium bromide 2-oxide gave a monobromo-derivative which was subsequently converted into 1-bromopyrido[1,2-a]pyrazin-5-ium bromide.