title: The enantioselective construction of tetracyclic diterpene skeletons with Friedel-Crafts alkylation and palladium-catalyzed cycloalkenylation reactions.
abstract: Due to the profound extent to which natural products inspire medicinal chemists in drug discovery, there is demand for innovative syntheses of these often complex materials. This article describes the synthesis of tricarbocyclic natural product architectures through an extension of the enantioselective Birch-Cope sequence with intramolecular Friedel-Crafts alkylation reactions. Additionally, palladium-catalyzed enol silane cycloalkenylation of the tricarbocyclic structures afforded the challenging bicyclo[3.2.1]octane C/D ring system found in the gibberellins and the ent-kauranes, two natural products with diverse medicinal value. In the case of the ent-kaurane derivative, an unprecedented alkene rearrangement converted four alkene isomers to one final product.
authors.affiliation: Department of Chemistry, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010-2899, USA. wmalacho@brynmawr.edu.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Burke
authors.forename: William P
authors.initials: WP
authors.lastname: Malachowski
authors.forename: Sharan K
authors.initials: SK
authors.lastname: Mehta
authors.forename: Roselyn
authors.initials: R
authors.lastname: Appenteng
mesh_terms: D000478:Alkylation; D001688:Biological Products / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D003500:Cyclization; D004224:Diterpenes / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D011083:Polycyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D001688:Biological Products; D004224:Diterpenes; D009942:Organometallic Compounds; D011083:Polycyclic Compounds; D010165:Palladium