ABSOLUTE CONFIGURATION OF MULINOLIC ACID

The structure of this mulinolic acid consists of a mulinane skeleton and the corresponding isopropyl, methyl, carboxyl and methyl groups at C3, C8, C5, C13, respectively, which are beta-oriented, whereas the hydroxyl group at C13 is alpha-oriented. The cyclopentane (A), ciclohexane (B) and cicloheptene (C) rings are trans (A/B) and (B/C) cis fused, and in an envelope, chair, and twist conformation respectively. In the crystal the molecules are linked by two intermolecular O-H center dot center dot center dot O hydrogen bond forming bidimensional supramolecular structures with graph-set notation R-4(4)(12), R-4(4)(40), R-6(6)(46) and C-4(4)(46). The absolute configuration of the title compound has been determined from the refinement of the Flack parameter(16). On this basis the absolute configuration was assigned as C3R, C5S, C8S, C9S, C10S and C13R.