Conformational analysis and absolute stereochemistry of 'spongian'-related metabolites

6 pages, 1 figure, 2 tables, 1 scheme.-- Available online Dec 30, 2003.New degraded and rearranged diterpenoids, 5–8, have been isolated from the Antarctic sponge Dendrilla membranosa. The structure and relative stereochemistry of these compounds were determined by spectroscopic data. The absolute stereochemistry of 5 was determined by spectroscopic data using a chiral reagent. Conformational studies allowed us to assign also the absolute stereochemistry of 6–8, as well as those previously isolated spongian-derived metabolites with known relative stereochemistries.This work was supported by Ministerio de Ciencia y Tecnología (MCYT, projects: REN2002-10485-E/ANT and PPQ2002-02494), Instituto Antártico Chileno (INACH), and DGUI (Gobierno de Canarias: PI2002/044). A.R.D.-M. acknowledges an I3P grant from the CSIC and E.D. acknowledges a fellowship (FPI) from the CICYT