Additivity relationships in the carbon-13 nuclear magnetic resonance spectra of polyhydroxy steroids
Abstract
δc Values for the 13C NMR spectra of polyhydroxy 5α,14α-steroids are, as a result of an additivity relationship, equivalent to the sum of the δc values of the individual 1,2- and 1,3-glycols present in the molecule. Differences in the experimental δc values (Δδg), reported for a variety of glycols, from those derived from addition of monohydroxy substituent effects, were converted into dihydroxy steroid parameters. Ancillary data for 8β-hydroxy steroids have also been derived. The dihydroxy steroid parameters were applied to 14 different types of known polyhydroxy steroid (6–19) to provide calculated δc values. The results indicate that, within reasonable limits, this method generally predicts δc values for polyhydroxy steroids which are close to those observed, except where there is severe steric hindrance present (e.g. as found in the 4β,6β,8β,15β-tetrahydroxylated steroid 19)