title: Total asymmetric syntheses of β-hydroxy-δ-lactones via Umpolung with sulfur dioxide.
abstract: Cyclic stereotriads and stereotetrads of the β-hydroxy-δ-lactone type, e.g. prelactones B and E, common in polyketides and polypropionates, are prepared via SO(2)-induced oxyallylations of enoxysilanes with (1E,3Z)-1-(1-phenylethoxy)penta-1,3-dien-3-yl carboxylates. Using (Z)- or (E)-enoxysilanes both 4,5-cis- or 4,5-trans-δ-lactones are obtained. Depending on the reduction method applied to the obtained aldol intermediates 5,6-trans or 5,6-cis-derivatives are formed. The δ-lactones can be prepared in both their enantiomeric forms depending on the (1R)- or (1S)-configuration of the starting 1-(1-phenylethoxy)penta-1,3-dienes.
authors.affiliation: Swiss Federal Institute of Technology Lausanne, Batochime, Switzerland.
authors.forename: Claudia J
authors.initials: CJ
authors.lastname: Exner
authors.forename: Sylvain
authors.initials: S
authors.lastname: Laclef
authors.forename: Florent
authors.initials: F
authors.lastname: Poli
authors.forename: Maris
authors.initials: M
authors.lastname: Turks
authors.forename: Pierre
authors.initials: P
authors.lastname: Vogel
mesh_terms: D000466:Alkadienes / Q000737:chemistry*; D007783:Lactones / Q000138:chemical synthesis* / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D013237:Stereoisomerism; D013458:Sulfur Dioxide / Q000737:chemistry*
chemical_list: D000466:Alkadienes; D007783:Lactones; D013458:Sulfur Dioxide