Chichibabin Amination of 1,X-Naphthyridines. Nuclear Magnetic Resonance Studies on the ? Adducts of Heterocyclic Systems with Nucleophiles

Article abstract of DOI:10.1021/jo00323a031

In the amination of 1,X-naphthyridines with potassium amide in liquid ammonia at about -35 to -40 deg C the initial adduct formation is charge controlled.Thus, at these temperatures the site with the lowest electron density is most susceptible for amide attack (C-2 in 1,5-naphthyridine, C-2 in 1,6-naphthyridine, C-2 and C-8 in 1,7-naphthyridine, and C-2 in 1,8-naphthyridine), as proven by NMR spectroscopy.When the temperature was raised to about 10 deg C, the site of addition has been found to change for 1,5- and 1,7-naphthyridine (NMR spectroscopy): from C-2 to C-4 in 1,5-naphthyridine and from C-2 and C-8 to C-8 only in 1,7-naphthyridine.In case of 1,6- and 1,8-naphthyridines no change was observed.Thus, the amination at about 10 deg C is a process which is thermodynamically controlled.The several factors which contribute to the stability of these addition products have been discussed.It has been found that the anionic ? adducts 2(4,8)-aminodihydro-1,X-naphthyridinides can be easily oxidized with potassium permanganate into their corresponding 2(4,8)-amino-1,X-naphthyridines.