As part of our efforts to exploit the antitrypanosomal potential of sesquiterpene lactones (STL) from Helianthus tuberosus L. (Asteraceae), besides the known 4,15-iso-atriplicolide tiglate, -methacrylate and -isobutyrate, a hitherto unknown STL was isolated. Its structure was solved by extensive NMR measurements and confirmed by single crystal X-ray crystallography. This novel compound is a structural analog 4,15-iso-atriplicolide tiglate that possesses the same basic furanoheliangolide skeleton but differs in the position of the oxo function which is at C-2 instead of C-1, as well as in the fact that the oxygen atom of the furanoid ring is part of a hemiketal structure at C-3 and a double bond between C-5 and C-6. For this new STL we propose the name heliantuberolide-8-O-tiglate. Its activity against Trypanosoma brucei rhodesiense (causative agent of East African Human Typanosomiasis, Trypanosoma cruzi (Chagas Disease), Leishmania donovani (Visceral Leishmaniasis) and Plasmodium falciparum (Tropical Malaria) as well as cytotoxicity against rat skeletal myoblasts (L6 cell line) was determined along with those of the hitherto untested 4,15-iso-atriplicolide methacrylate and isobutyrate. In comparison with the iso-atriplicolide esters, the new compound showed a much lower level of bioactivity.

Keywords: Oxidation / Olefination / Palladium / StereochemistryOxidation of 4,6-heptadienoic acid systems with hydrogen peroxide in the presence of a catalytic amount of diphenyl diselenide leads to 5-(3-hydroxypropenyl)dihydrofuran-2-one systems with defined relative configuration at the 4 and 7 positions (carboxylic acid numbering). A system having a six-membered ring as part of the s-trans-diene system was an intermediate in a strigol total synthesis; a second system lacking the six-membered ring is the subject of the present publication. We accomplished a stereoselective synthesis of

A substrate controlled asymmetric synthesis is described of a highly functionalized cyclopentanyl vinyl triflate which serves as an advanced intermediate in the total synthesis of the novel multidrug resistance reversing jatrophanes pepluanin A and euphosalicin. Key steps are a Claisen-Eschenmoser rearrangement followed by hydroxy-lactonization, intramolecular trans-lactonization, Davis hydroxylation and regioselective enoltriflate formation.