title: Stereoselective Nazarov cyclizations of bridged bicyclic dienones.
abstract: [reaction: see text] Bridged bicyclic dienones underwent silyl-directed Nazarov cyclization with generally very high diastereoselectivity. In most cases, a strong preference for cyclization to the product with an exo-disposed cyclopentenone was seen. However, the presence of additional unsaturation in the three-carbon bridge of a bicyclo[3.2.1]octadiene system caused complete reversal in selectivity with exclusive formation of the endo-cyclopentenone. The observed selectivities are believed to result from a combination of steric and electronic effects.
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850, USA.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Mazzola
authors.forename: Timothy D
authors.initials: TD
authors.lastname: White
authors.forename: Heidi R
authors.initials: HR
authors.lastname: Vollmer-Snarr
authors.forename: F G
authors.initials: FG
authors.lastname: West
mesh_terms: D001643:Bridged Bicyclo Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D003517:Cyclopentanes / Q000138:chemical synthesis*; D007202:Indicators and Reagents; D007659:Ketones / Q000138:chemical synthesis* / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D001643:Bridged Bicyclo Compounds; D003517:Cyclopentanes; D007202:Indicators and Reagents; D007659:Ketones; C007201:cyclopentanone