title: Collective Syntheses of Icetexane Natural Products Based on Biogenetic Hypotheses.
abstract: A divergent synthesis of 10 icetexane natural products based on a proposed biogenetic cationic ring expansion of a reduced carnosic acid derivative is described. Of these icetexanes, (+)-salvicanol, (-)-cyclocoulterone, (-)-coulterone, (-)-obtusinone D, and (-)-obtusinone E have been synthesized for the first time. In addition, the hypothesis for the non-enzymatic biogenesis of benzo[1,3]dioxole natural products has been experimentally investigated. Additional experimental evidence for the abiotic formation of the methylenedioxy unit is provided, as photolysis of the quinone (+)-komaroviquinone resulted in the formation of the [1,3]dioxole-containing natural product (-)-cyclocoulterone and (+)-komarovispirone.
authors.affiliation: Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.|Department of Chemistry, University of Basel, St-Johanns-Ring 19, 4056, Basel, Switzerland.
authors.forename: Christophe
authors.initials: C
authors.lastname: Thommen
authors.affiliation: Department of Chemistry, University of Basel, St-Johanns-Ring 19, 4056, Basel, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Neuburger
authors.affiliation: Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.|Department of Chemistry, University of Basel, St-Johanns-Ring 19, 4056, Basel, Switzerland.
authors.forename: Karl
authors.identifier: http://orcid.org/0000-0003-3053-0689
authors.initials: K
authors.lastname: Gademann
mesh_terms: D001688:Biological Products / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D061565:Cycloaddition Reaction; D004224:Diterpenes / Q000138:chemical synthesis* / Q000737:chemistry; D008956:Models, Chemical; D008968:Molecular Conformation; D010782:Photolysis / Q000187:drug effects; D011809:Quinones / Q000138:chemical synthesis / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D001688:Biological Products; D004224:Diterpenes; D011809:Quinones; C512853:icetexone; C508550:komaroviquinone
keywords: C−H activation; Diels-Alder reactions; natural products; reaction mechanisms; ring expansion