Collect. Czech. Chem. Commun. 1986, 51, 903-929

Structure of isosilerolide, relative and absolute configuration of silerolide and lasolide - Sesquiterpenic lactones of new stereoisomeric type of eudesmanolides

Miroslav Holuba, Miloš Buděšínskýa, Zdenka Smítalováa, David Šamana and Urszula Rychłewskab

a Institute of Organic Chemistry and Biochemistry, Czechoslovak Academ of Sciences, 166 10 Prague 6, Czechoslovakia
b Laboratory of Crystallography, Department of Chemistry, Adam Mickiewicz University, Poznan, Poland


On the basis of spectroscopic, particularly 1H NMR data, isosilerolide was assigned structure I, including the absolute configuration. The structure was confirmed by X-ray diffraction. Isosilerolide represents a new stereoisomeric type of natural eudesmanolides, characterized as 5βH, 6αH, 7αH, 10αCH3-eudesman-6,12-olide. As shown by the chemical correlation of isosilerolide (I) with silerolide (III) and lasolide (X), the latter two natural lactones belong to this stereoisomeric group of eudesmanolides. Analysis of models and 1H NMR data shows that structures of some eudesman-6,12-olides, published by other authors, should be corrected.