Stereochemistry of 16a-Hydroxyfriedelin and 3-Oxo-16-methylfriedel-16-ene Established by 2D NMR Spectroscopy

Stereochemistry of 16a-Hydroxyfriedelin and 3-Oxo-16-methylfriedel-16-ene Established by 2D NMR Spectroscopy

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Friedelin (1), 3b-friedelinol (2), 28-hydroxyfriedelin (3), 16a-hydroxyfriedelin (4), 30-hydroxyfriedelin (5) and 16a,28-dihydroxyfriedelin (6) were isolated through fractionation 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 ut solution gel for cats 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 ivoryjinelle.com 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 13C-NMR and 2D NMR spectral data are reported for compounds 4 and 7.