13C-NMR. Spectral Differences between Corresponding Methyl Esters, Phenyl Esters and 2-Substituted Chromones

Article abstract of DOI:10.1002/hlca.19810640824

The 13C-NMR. spectra of 2-substituted chromones (3) are compared with the data of the analogous methyl and phenyl esters (1 and 2).The chemical shift differences found are most prominent for the C-atoms in β-position to the ester carbonyl and chromone C(2), respectively.These shift differences are discussed in terms of conformational differences between the esters 1 and 2 and the analogous chromones 3.