title: Planar Chiral, Ferrocene-Stabilized Silicon Cations.
abstract: The preparation of a series of planar chiral, ferrocenyl-substituted hydrosilanes as precursors of ferrocene-stabilized silicon cations is described. These molecules also feature stereogenicity at the silicon atom. The generation and (29)Si NMR spectroscopic characterization of the corresponding silicon cations is reported, and problems arising from interactions of the electron-deficient silicon atom and adjacent C(sp(3))-H bonds or aromatic π donors are discussed. These issues are overcome by tethering another substituent at the silicon atom to the ferrocene backbone. The resulting annulation also imparts conformational rigidity and steric hindrance in such a way that the central chirality at the silicon atom is set with complete diastereocontrol. These chiral Lewis acid catalysts were then tested in difficult Diels-Alder reactions, but no enantioinduction was seen.
authors.affiliation: Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623, Berlin, Germany), Fax.|Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149, Münster, Germany.
authors.forename: Ruth K
authors.initials: RK
authors.lastname: Schmidt
authors.affiliation: Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623, Berlin, Germany), Fax.|Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149, Münster, Germany.
authors.forename: Hendrik F T
authors.identifier: http://orcid.org/0000-0003-3748-6609
authors.initials: HF
authors.lastname: Klare
authors.affiliation: Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149, Münster, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Fröhlich
authors.affiliation: Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623, Berlin, Germany), Fax. martin.oestreich@tu-berlin.de.|Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149, Münster, Germany. martin.oestreich@tu-berlin.de.
authors.forename: Martin
authors.identifier: http://orcid.org/0000-0002-1487-9218
authors.initials: M
authors.lastname: Oestreich
keywords: Lewis acids; cations; chirality; metallocenes; silicon