title: A short access to the skeleton of Elisabethin A and formal syntheses of Elisapterosin B and Colombiasin A.
abstract: A short stereoselective synthesis of the Elisabethin A skeleton 4 is described, which opens a formal access to the diterpenes Elisapterosin B and Colombiasin A as well. Key reactions were an intermolecular endo-selective Diels-Alder reaction to generate the decalin part of the molecule, a chemo- and diastereoselective allylation of an aldehyde with allylzinc, a palladium ene annulation of the cyclopentane ring, and a novel sulfonium ylide induced fragmentation of a polycyclic ketone. Additional insights have been gained for the crucial epimerization at C-2.
authors.affiliation: University of Vienna , Institute of Organic Chemistry, Waehringer Strasse 38, 1090 Wien, Austria.
authors.forename: Johannes
authors.initials: J
authors.lastname: Preindl
authors.forename: Christian
authors.initials: C
authors.lastname: Leitner
authors.forename: Simon
authors.initials: S
authors.lastname: Baldauf
authors.forename: Johann
authors.initials: J
authors.lastname: Mulzer
mesh_terms: D001952:Bridged-Ring Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D004224:Diterpenes / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D001952:Bridged-Ring Compounds; D004224:Diterpenes; C408889:colombiasin A; C474511:elisabethin A; C414524:elisapterosin B