title: Enantioselective total synthesis of cyathin A3.
abstract: The total synthesis of (-)-cyathin A3 is described. The key step involves an unusual enantioselective Diels-Alder reaction of 2,5-dimethyl-1,4-benzoquinone with 2,4-bis(trimethylsilyloxy)-1,3-pentadiene, using Mikami's catalyst [(R)-BINOL + Cl2Ti(OiPr)2 + 4 A mol sieves] modified by addition of Mg and SiO2. Because cyathin A3 is easily transformed into allocyathin B3, cyathin B3, cyathin C3, and neoallocyathin A4, this route also constitutes formal syntheses of these natural products.
authors.affiliation: Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Canada. dale.ward@usask.ca
authors.forename: Dale E
authors.initials: DE
authors.lastname: Ward
authors.forename: Jianheng
authors.initials: J
authors.lastname: Shen
mesh_terms: D004224:Diterpenes / Q000138:chemical synthesis*; D006860:Hydrogen Bonding; D013237:Stereoisomerism
chemical_list: D004224:Diterpenes; C007179:cyathins