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Epoxidation‐induced shifts in the carbon‐13 NMR spectra of steroids: Lanostane derivatives
Author(s) -
Martynow Jacek,
Paryzek Zdzisław
Publication year - 1989
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.1260270313
Subject(s) - chemistry , lanosterol , lanostane , epoxide , chemical shift , stereochemistry , carbon 13 nmr , stereospecificity , computational chemistry , organic chemistry , triterpene , medicine , biochemistry , alternative medicine , sterol , pathology , cholesterol , catalysis
The 13 C chemical shifts of triterpenoidal olefins and epoxides related to lanosterol are described and discussed. The epoxide function located in the central part of the tetracyclic steroidal skeleton allows the evaluation of epoxidation‐induced shifts (EIS) for several carbons. The most characteristic and valuable for stereochemical assignments are the EIS values for γ‐carbons C‐1, C‐5, C‐12, C‐19 and C‐28 in 8α,9α‐epoxides, and C‐1 and C‐19 in 9α,11α‐epoxides. The C‐α effect (EIS −55 to −79 ppm) is found to be susceptible to minor conformational distortions of the molecular framework. Characteristic signals are discussed in terms of their predictive value for each group of analysed compounds.