1.
Tetrahedron Lett
; 50(35): 5018-5020, 2009 Sep 02.
Artigo
em Inglês
| MEDLINE
| ID: mdl-20161133
RESUMO
Substituents on the pyridinium ring of N-methylpyridinium derivatives, especially those on the 2- or 4-positions, have a large effect on the (1)H and (13)C NMR chemical shifts of the N-methyl group. Reasonable correlations between the chemical shift changes and the resonance substituent constants are observed. The dual substituent parameter approach provides an excellent correlation when a combination of polar and resonance substituent constants is employed.