The synthesis and properties of quinolizinium and related compounds

Abstract

The work describes the preparation and properties of several simple quinolizinium salts particularly hydroxyquinolizinium derivatives. 1- and 2-Hydroxyquinolizinium salts have been prepared in high yields from 1-oxo-1,2,3,4-tetrahydroquinolizinium bromide. The 2-hydroxyquinolizinium ion has also been converted to the related compound, 2-quinolizone. Some
1,2-dihydroxyquinolizinium salts have been prepared.

1-Hydroxyquinolizinium salts are shown to be phenolic, readily undergoing acetylation, brominaiion and coupling with diazotised aniline. However, nitration is abnormal giving a series of compounds having zwitterionic structures. The 2-hydroxyquinolizinium salts behave to some extent as phenols but 2-quinolizone, as expected, has properties resembling the 2- and 4-pyridones.

The rearrangements of 1-oximino- 1,2,3,4-tetrahydroquinolizinium bromide have been investigated and total syntheses of both possible Beckmann rearrangement products are reported. Under certain acid conditions the oxime rearranges to give aminohydroxyquinolizinium salts. These have been formulated as 1-amino-2-hydroxy and 1-amino-4-hydroxyquinolizinium
compounds.

Attempts have been made to synthesise the 1- and 3-oxo pyrido[1,2a]-azepinium systems. Although the preparation of the unsubstituted compounds has not been successful several compounds in the 1-oxo pyrido[1,2a]-azepinium series have been synthesised.

Citation

(1964). The synthesis and properties of quinolizinium and related compounds