Plumeridoid C from the Amazonian traditional medicinal plant Himatanthus sucuuba

Abstract

The stereochemistry of the iridoid plumeridoid C, C 15H 18O 7, was established by X-ray single-crystal structure analysis, giving (2′R,3R,4R,4aS,7aR)-methyl 3-hy-droxy-4′-[(S)-1- hydroxy-eth-yl]-5′-oxo-3,4,4a,7a-tetra-hydro-1H,5′H-spiro- [cyclopenta-[c]pyran-7,2′-furan]-4-carboxyl-ate. The absolute structure of the title compound was determined on the basis of the Flack x parameter and Bayesian statistics on Bijvoet differences. The hydrogen-bond donor and acceptor functions of the two hy-droxy groups are employed in the formation of O - H⋯O-bonded helical chains. © 2011 International Union of Crystallography.