Structural Studies on the Triterpene Obliquol

Oxidation studies have indicated that the two hydroxyl groups of obliquol are secondary, one of which exhibits some hindrance as in the Oppenauer oxidation. Nuclear magnetic resonance studies have supported the chemical evidence that the second hydroxyl group is in the 12 position in obliquol. The C-18 methyl peak of obliquol diacetate has shifted downfield from the corresponding peak in lanosterol acetate due to perturbation by the 12-acetyl group. Therefore, it was concluded that obliquol has the structure I. The complete NMR spectra of obliquol, lanosterol, and their acetates are interpreted.