A conformational investigation of zearalenone and the 6′‐zearalenols by carbon and proton NMR spectroscopy

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Abstract
The carbon and proton spectra for zearalenone and its two C‐6′ alcohol derivatives have been assigned using 2D techniques along with NOE difference spectra and the LIS of the dimethoxy derivative of the β‐alcohol. Low temperature and relaxation time studies on the latter compound support the existence of only one solution conformer for each molecule. Molecular mechanics calculations for each molecule predict the existence of several low energy conformers which differ in energy by less than 3 kcal/mol; however, barriers to conformational interchange could not be estimated. Partial analysis of the proton spectra allows a comparison of the NMR parameters with the MM derived conformations and with x‐ray structural data. The solution conformations of zearalenone and α‐zearalenol are closely related to the solid state conformations.