Proton and Carbon-13 Nuclear Magnetic Resonance Investigations on σ-Adduct Formation between l, X-Naphthyridines and Some Methyl-1,8-naphthyridines with Potassium Amide in Liquid Ammonia

1, 5-, 1, 6-and 1,8-naphthyridines dissolved in liquid ammonia containing potassium amide showed the H-2 and C-2 resonances at about 4 and 90 ppm higher field, respectively, than the H-2 and C-2 resonances observed in solutions of these naphthyridines in CDCl3. It indicated that all three naphthyridines underwent addition of the amide ion to position 2, yielding a 2-amino-l,2-dihydro-l,X-naphthyridinide ion. The 1,7-naphthyridine showed a more complex reactivity pattern toward amide ions. Besides addition at C-2, addition at C-6 and at C-8 has been found. The relation of this study with that of the Chichibabin amination of the I, X-naphthyridines is discussed. It was further proven that under the influence of the amide ion 2-methyl-and 4-methyl-l,8-naphthyridine only gave de-protonation of the methyl group and that 3-methyl-l,8-naphthyridine gave formation of the 2-amino-l,2-dihydro-3-methyl-l,8-naphthyridinide ion