title: A novel synthesis of functionalized tetrahydrofurans by an Oxa-Michael/Michael cyclization of gamma-hydroxyenones.
abstract: An approach to highly functionalized tetrahydrofuran derivatives based upon a novel Oxa-Michael/Michael dimerization of cis-gamma-hydroxyenones is presented. The reaction begins with either 1,2-dioxines or trans-gamma-hydroxyenones and proceeds by addition of one molecule of trans-gamma-hydroxyenone to another molecule of cis- or trans-gamma-hydroxyenone catalyzed by an alkoxide or hydroxide base. Subsequent intramolecular Michael addition of the keto-enolate gives the observed tetrahydrofurans. Substitution at both the 2- and 4-positions of the gamma-hydroxyenone is tolerated; however, for 4-substituted gamma-hydroxyenones, selectivity issues arise due to the possibility of heterochiral or homochiral dimerizations. The major products were those with all contiguous groups trans.
authors.affiliation: Department of Chemistry, The University of Adelaide, South Australia 5004, Australia.
authors.forename: Ben W
authors.initials: BW
authors.lastname: Greatrex
authors.forename: Marc C
authors.initials: MC
authors.lastname: Kimber
authors.forename: Dennis K
authors.initials: DK
authors.lastname: Taylor
authors.forename: Edward R T
authors.initials: ER
authors.lastname: Tiekink