Structure of laserolide and isolaserolide: Revision of constitution and determination of relative and absolute configuration

Abstract

The position of the ester groups in sesquiterpenic lactones laserolide (I) and isolaserolide (II) has been revised and its relative and absolute configuration determined by chemical and physical methods (NMR and CD spectroscopy). The structure I was confirmed by X-ray diffraction analysis. Laserolide (I) is the first germacranolide found in the Umbelliferae family, isolaserolide (II) is the first representative of new stereostructural group of elemanolides - 5βH,6αH,7αH,10αCH3-elema-1,3-dien-6,12-olides.