Carbon-13 NMR spectra of N-methylimidazole-substituted sterol esters

The ¹³C NMR spectra of two N-methylimidazole-substituted sterol esters are discussed. The calculated shifts are compared to those obtained experimentally. For one of the sterol esters the experimental and calculated data show good agreement, and the substituent increments can be evaluated. This does not apply in the case of the second sterol ester, where the steric and/or electronic effects of a further substituent—a hydroperoxy group in close proximity to the N-methylimidazole group—prohibits the additive calculation of substituent increments.