Stereochemistry of 16a-hydroxyfriedelin and 3-Oxo-16-methylfriedel-16-ene established by 2D NMR spectroscopy

Molecules. 2009 Feb 4;14(2):598-607. doi: 10.3390/molecules14020598.

Abstract

Friedelin (1), 3beta-friedelinol (2), 28-hydroxyfriedelin (3), 16alpha-hydroxyfriedelin (4), 30-hydroxyfriedelin (5) and 16alpha,28-dihydroxyfriedelin (6) were isolated through fractionation of the hexane extract obtained from branches of Salacia elliptica. After a week in CDCl(3) solution, 16alpha-hydroxyfriedelin (4) reacted turning into 3-oxo-16-methylfriedel-16-ene (7). This is the first report of a dehydration followed by a Nametkin rearrangement of a pentacyclic triterpene in CDCl(3) solution occurring in the NMR tube. These seven pentacyclic triterpenes was identified through NMR spectroscopy and the stereochemistry of compound 4 and 7 was established by 2D NMR (NOESY) spectroscopy and mass spectrometry (GC-MS). It is also the first time that all the (13)C-NMR and 2D NMR spectral data are reported for compounds 4 and 7.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Drugs, Chinese Herbal / chemistry
  • Magnetic Resonance Spectroscopy* / methods
  • Molecular Conformation
  • Molecular Structure
  • Salacia / chemistry
  • Stereoisomerism
  • Triterpenes / chemistry*

Substances

  • Drugs, Chinese Herbal
  • Triterpenes
  • friedelin