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1 H NMR structural analysis of isomeric tetrazole‐substituted spirostan steroids: Shielding effects and conformational study
Author(s) -
Silwood Christopher J. L.,
Davies David B.
Publication year - 1991
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260290113
Subject(s) - chemistry , tetrazole , ring (chemistry) , isomerization , chemical shift , stereochemistry , proton nmr , proton , crystallography , organic chemistry , physics , quantum mechanics , catalysis
The structures of two pairs of tetrazole‐substituted spirostan steroids were characterized by the use of one‐ and two‐dimensional 1 H NMR measurements. The conformation of the seven‐membered spirostan ring A of the steroid was determined by analysis of proton spin coupling constants and confirmed by 1D and 2D NOE experiments showing interactions between the methyl group and ring protons. The conformation of the tetrazole‐substituted ring A was found to be the same for the four isomers, allowing them to be differentiated by the analysis of the effect of tetrazole‐ring isomerization on the chemical shifts of neighbouring protons.