Carbon-13 N.M.R. spectra of 6β-Substituted-5α-cholestane-3β,5-diols: γ- and δ-effects

Abstract

The carbon-13 N.M.R. spectra of a series of 6β-substituted-5α- cholestane-3β,5-diols have been determined. The γ- and δ-shifts associated with those carbons involved in a direct steric interaction with the 6β-substituent, i.e. C4, C8, C10 and C19, are found to be upfield or downfield depending on the nature of the substituent and its geometric relationship to the observed carbon. In particular, the-δ- shifts at C19 are increasingly downfield as the size of the substituent is increased.