Pinnatane A from the bark of Walsura pinnata Hassk

In the molecule of pinnatane A, C30H48O3, isolated from the bark of Walsura pinnata Hassk, the four cyclohexane rings adopt chair conformations; the carboxyl and hydroxy substituents occupy axial positions. The cyclohexene ring is envelope-shaped. Adjacent molecules are linked by O—H⋯O hydrogen bonds into a chain running along the c axis.

In the molecule of pinnatane A, C 30 H 48 O 3 , isolated from the bark of Walsura pinnata Hassk, the four cyclohexane rings adopt chair conformations; the carboxyl and hydroxy substituents occupy axial positions. The cyclohexene ring is envelope-shaped. Adjacent molecules are linked by O-HÁ Á ÁO hydrogen bonds into a chain running along the c axis.
oolean-1-en-28-oic acid (Awang et al., 2009), which was obtained from one fraction of the crude extract of the bark of this plant. The last fraction yielded the title compound, which we have named pinnatane A. A related carbon skeleton, assigned from spectroscopic measurements, has been reported (Jiang et al., 1995).
In the molecule of pinnatane A (Fig. 1) the four cyclohexane rings adopt chair comformations, with axial carboxylic acid and hydroxy substituents. The cyclohexene ring is envelope-shaped. Adjacent molecules are linked by O-H···O hydrogen bonds into a chain running along the longest axis of the orthorhombic unit cell.

Experimental
The dried and ground bark of Walsura pinnata Hassk (2.3 kg) was extracted with n-hexane for 72 h at room temperature.
The solvent was evaporated to give a crude extract, which was subjected to column chromatography on silica gel (60 GF254), using n-hexane with increasing amounts of ethyl acetate as eluent. Of the twenty-four fractions collected, the twenty-fourth fraction, eluted with ethyl acetate:n-hexane (14:86) gave 2 g of the product, which was further purified by column chromatography (n-hexane:acetone, 94:6) to give the title compound (5 mg). The formulation was established by satisfactory solution NMR spectroscopy.

Refinement
Carbon-bound H-atoms were placed in calculated positions (C-H 0.95-1.00 Å) and were included in the refinement in the riding model approximation, with U iso (H) set to 1.2-1.5U eq (C). The oxygen-bound H-atoms were located in a difference Fourier map, and were refined with a distance restraint of 0.84±0.01 Å; their displacement parameters were freely refined.