Proton NMR spectral studies on N-(4-methylphenyl)-2- and 3-pyridinecarboxamides

The H-1 NMR spectra of N-(4-methylphenyl)-2-pyridinecarboxamide and N-(4-me thyl-phenyl)-3-pyridine carboxamide in CDCl3 and (CD3)(2)CO have been analy sed with the help of the COSY spectra. Accurate H-1 chemical shifts and cou pling constants have been obtained from the simulated spectra. From H-1 NMR and Nuclear Overhauser Enhancement (NOE) measurements the molecular confor mations are inferred. The pyridyl ring is apparently coplanar with the amid e group while the 3-pyridyl ring is nearly perpendicular to the amide plane so that the amide proton is nearer to the 2-pyridyl proton H2 than to H4. The orientation of the 4-methylphenyl group could not be determined.