Skip to main content

Substituted Methyl 5-BETA-Cholan-24-oATES .1. 0-17 NMR Spectral Characterization

Kolehmainen, Erkki, Kaartinen, Mari, Kauppinen, Reijo, Kotoneva, Jari, Lappalainen, Kari, Lewis, Philip A., Seppala, Raimo, Sundelin, Jukka, Vatanen, Virpi (1994) Substituted Methyl 5-BETA-Cholan-24-oATES .1. 0-17 NMR Spectral Characterization. Magnetic Resonance in Chemistry, 32 (8). pp. 441-445. ISSN 0749-1581. (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided) (KAR id:20294)

The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided.


Methyl esters of tour common bile acids, 3 alpha-hydroxy-5 beta-cholan-24-oic (lithocholic) acid, 3 alpha,7 alpha-dihydroxy-5 beta-cholan-24-oic (chenodeoxycholic) acid, 3 alpha,12 alpha-dihydroxy-5 beta-cholan-24-oic (deoxycholic) acid and 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholan-24-oic (cholic) acid, and 14 acetylated, trifluoroacetylated, mesylated and ore derivatives of methyl 5 beta-cholan-24-oates were prepared and their O-17 NMR spectra recorded. In spite of their relatively high molecular masses and the rigid molecular structure of the steroid skeleton, most of the oxygens included in these structures gave well resolved O-17 NMR resonance lines at natural abundance in 0.25-0.5 M acetonitrile solutions at 75 degrees C. In agreement with the present O-17 NMR results, molecular mechanics calculations revealed that a hydroxy substituent located at the 3 alpha-position clearly differs from the hydroxyls at the 7 alpha- and 12 alpha-positions. This is due to the fact that the 3 alpha-hydroxyl possessing only two gamma-carbons at antiperiplanar positions is less shielded than the other hydroxyls influenced also by the shielding effects of gamma-gauche carbons. The spectral deconvolution of the overlapping signals of the 7 alpha- and 12 alpha-hydroxyls is based on a computer-aided method or on chemical substitutions. The oxo groups located at the longitudinal (fore) vs. transversal (7- and 12-oxo) axes of the steroid framework show very different quadrupolar relaxation properties and O-17 NMR linewidths owing to the strong anisotropy of overall molecular motion. In contrast, the O-17 NMR linewidths of all 3 alpha-, 7 alpha- and 12 alpha-hydroxyls are very similar and clearly smaller than those of the corresponding oxo groups, revealing that their quadrupolar relaxation is merely determined by their internal rotation rather than by the overall molecular motion.

Item Type: Article
Subjects: Q Science > QD Chemistry
Divisions: Divisions > Division of Computing, Engineering and Mathematical Sciences > School of Engineering and Digital Arts
Depositing User: P. Ogbuji
Date Deposited: 25 Jun 2009 07:40 UTC
Last Modified: 16 Nov 2021 09:58 UTC
Resource URI: (The current URI for this page, for reference purposes)
  • Depositors only (login required):