Cyclic quaternary ammonium salts. Part IX. 1,1′-Azoimidazo[1,2-a]-pyridinium salts

The synthesis of 1-aminoimidazo[1,2-a]pyridinium salts by cyclisation of the quaternary salts derived from 2-pyridyl-acethydrazide and suitable bromo-aldehydes or ketones and their oxidation to the title compounds is described.