134858-06-3Relevant academic research and scientific papers
Sites of Protonation in Cardiotonic Polyazaindolizines by NMR Spectroscopy
Barraclough, Paul,Firmin, David,Lindon, John C.,Nobbs, Malcolm S.,Sanderson, Paul N.,et al.
, p. 468 - 475 (1991)
The pKa values of six sulmazole analogues were measured spectrophotometrically.The major protonation sites for most of these bridgehead nitrogen heterocycles were determined by 1H and 13C NMR methods.The arylsubstituted imidazopyrimidine (4), 8-methoxyimidazopyrazine (6), imidazopyridazine (9) and imidazotriazine (11) undergo protonation at the imidazo nitrogen.The imidazopyrazine (5) protonates mainly at N-7.In some cases differences in basicity properties between these aryl analogues and the bridgehead heterocycles have been observed.KEY WORDS Polyazaindolizines Protonation 13C NMR 1H NMR pK values
