title: Asymmetric catalysis with silicon-based cuprates: enantio- and regioselective allylic substitution of linear precursors.
abstract: An enantio- and regioselective allylic silylation of linear allylic phosphates that makes use of catalytically generated cuprate-type silicon nucleophiles is reported. The method relies on soft bis(triorganosilyl) zincs as silicon pronucleophiles that are prepared in situ from the corresponding hard lithium reagents by transmetalation with ZnCl2 . With a preformed chiral N-heterocyclic carbene-copper(I) complex as catalyst, exceedingly high enantiomeric excesses are achieved. The new method is superior to existing ones using a silicon-boron reagent as the source of the silicon nucleophile.
authors.affiliation: Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin (Germany) http://www.organometallics.tu-berlin.de.
authors.forename: Alexander
authors.initials: A
authors.lastname: Hensel
authors.affiliation: Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin (Germany) http://www.organometallics.tu-berlin.de. martin.oestreich@tu-berlin.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Oestreich
keywords: allylic substitution; asymmetric catalysis; copper; silicon; zinc