Imination of N ‐methylazinium salts by liquid ammonia/potassium permanganate

Treatment of 1‐methylquinolinium‐, 1,4‐dimethylquinolinium‐ and 1‐methyl‐1,X‐naphthyridinium iodides (X = 5,8) with liquid ammonia/potassium permanganate leads to introduction of the imino group at C‐2 forming the 1,2‐dihydro‐2‐imino‐1‐methylquinolines and 1,2‐dihydro‐2‐imino‐1‐methyl‐1,X‐naphthyridines (X = 5,8) respectively. 1,2‐Dimethylquinolinium iodide, when subjected to treatment with liquid ammonia/potassium permanganate undergoes an oxo‐demethylation reaction, yielding 1‐methylquinol‐2‐one. The nmr‐measurements of solutions of the above‐mentioned salts in liquid ammonia clearly show the formation of a σ‐adduct, strongly suggesting that these σ‐adducts are intermediates in the imination reactions.