title: Total synthesis of (+)-crotogoudin.
abstract: Fellowship of the ring: The first total synthesis of (+)-crotogoudin, a 3,4-seco-atisane diterpenoid natural product, is reported. Asymmetric access to the bicyclo[2.2.2]octane core is achieved through a desymmetrization of a meso-diketone with baker's yeast (LG=leaving group, PG=protecting group). A SmI2 -induced radical cyclopropane-opening/annulation/elimination cascade affords the suitably decorated tetracyclic structure of (+)-crotogoudin. The synthesis led to revision of the reported optical rotation of the natural product and to assignment of its absolute configuration as an ent-atisane (5R,10R).
authors.affiliation: Laboratorium für Organische Chemie, ETH Zürich, HCI H335, Wolfgang-Pauli-Strasse 10, 8093 Zürich (Switzerland) http://www.carreira.ethz.ch.
authors.forename: Simon
authors.initials: S
authors.lastname: Breitler
authors.forename: Erick M
authors.initials: EM
authors.lastname: Carreira
mesh_terms: D018360:Crystallography, X-Ray; D004224:Diterpenes / Q000138:chemical synthesis*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D004224:Diterpenes; C000600507:crotogoudin
keywords: cyclopropanation; natural products; radical cascade; samarium iodide; total synthesis