title: Construction of quaternary stereogenic carbon centers through copper-catalyzed enantioselective allylic cross-coupling with alkylboranes.
abstract: A combination of an in situ generated chiral Cu(I) /DTBM-MeO-BIPHEP catalyst system and EtOK enabled the enantioselective SN 2'-type allylic cross-coupling between alkylborane reagents and γ,γ-disubstituted primary allyl chlorides with enantiocontrol at a useful level. The reaction generates a stereogenic quaternary carbon center having three sp(3) -alkyl groups and a vinyl group. This protocol allowed the use of terminal alkenes as nucleophile precursors, thus representing a formal reductive allylic cross-coupling of terminal alkenes. A reaction pathway involving addition/elimination of a neutral alkylcopper(I) species with the allyl chloride substrate is proposed.
authors.affiliation: Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan) http://wwwchem.sci.hokudai.ac.jp/∼orgmet/index.php.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Hojoh
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Shido
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Ohmiya
authors.forename: Masaya
authors.initials: M
authors.lastname: Sawamura
keywords: allylic compunds; asymmetric catalysis; boron; copper; synthetic methods