Crystal structure of Staudtienic acid, a diterpenoid from Staudtia kamerunensis Warb. (Myristicaceae)

This title compound, C20H26O2, was isolated from the benzene fraction of the stem bark of Staudtia kamerunensis Warb. (Myristicaceae) using column chromatography techniques over silica gel. The compound was fully characterized by single-crystal X-ray diffraction, one and two-dimensional NMR spectroscopy, IR and MS spectrometry. The compound has two fused cyclohexane rings attached to a benzene ring, with a carboxylic acid on C-4. This cyclohexene ring has a chair conformation while the other adopts a half-chair conformation. The benzene ring is substituted with a propenyl moiety. The structure is characterized by intermolecular O-H⋯O hydrogen bonds, two C-H⋯O intramolecular hydrogen bonds and two C-H⋯π interactions. The molecular structure confirms previous studies carried out by spectroscopic techniques.