Additivity relationships in the carbon-13 nuclear magnetic resonance spectra of polyhydroxy steroids

Abstract

δ_c 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 δ_c values of the individual 1,2- and 1,3-glycols present in the molecule. Differences in the experimental δ_c values (Δδ^g), 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 δ_c values. The results indicate that, within reasonable limits, this method generally predicts δ_c 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)