title: Asymmetric Synthesis of β-Substituted α-Methylenebutyro- lactonesviaTRIP-Catalyzed Allylation: Mechanistic Studies and Application to the Synthesis of (S)-(-)-Hydroxymatairesinol.
abstract: Asymmetric allylation of (hetero)aromatic aldehydes by a zinc(II)-allylbutyrolactone species catalyzed by a chiral BINOL-type phosphoric acid gave β-substituted α-methylenebutyrolactones in 68 to >99%eeand 52-91% isolated yield. DFT studies on the intermediate Zn2+-complex - crucial for chiral induction - suggest a six-membered ring intermediate, which allows the phosphoric acid moiety to activate the aldehyde. The methodology was applied to the synthesis of the antitumour natural product (S)-(-)-hydroxymatairesinol.
authors.affiliation: Department of Chemistry, University of Graz, Heinrichstraße 28, 8010 Graz, Austria, ; phone: (+43)-(0)316-380-5332.
authors.forename: Michael
authors.initials: M
authors.lastname: Fuchs
authors.affiliation: Department of Chemistry, University of Graz, Heinrichstraße 28, 8010 Graz, Austria, ; phone: (+43)-(0)316-380-5332.
authors.forename: Markus
authors.initials: M
authors.lastname: Schober
authors.affiliation: Department of Chemistry, Ångström Laboratories, Uppsala University, Box 523, 75120 Uppsala, Sweden, ; phone: (+46)-018-471-6585.
authors.forename: Andreas
authors.initials: A
authors.lastname: Orthaber
authors.affiliation: Department of Chemistry, University of Graz, Heinrichstraße 28, 8010 Graz, Austria, ; phone: (+43)-(0)316-380-5332.
authors.forename: Kurt
authors.initials: K
authors.lastname: Faber
keywords: asymmetric allylation; butyrolactones; chiral phosphoric acids; hydroxymatairesinol; organozinc reagents