Friedelin (1), 3b-friedelinol (2), 28-hydroxyfriedelin (3), 16a-hydroxyfriedelin (4), 30-hydroxyfriedelin (5) and 16a,28-dihydroxyfriedelin (6) were isolated through fractionation click here of the hexane extract obtained from branches of Salacia elliptica.After a week in CDCl3 solution, 16a-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 CDCl3 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 custom congratulations banner NMR (NOESY) spectroscopy and mass spectrometry (GC-MS).It is also the first time that all the 13C-NMR and 2D NMR spectral data are reported for compounds 4 and 7.