title: Diastereodivergent behavior of alkyl versus cyano allenylcuprates toward aldehydes: a key role for lithium.
abstract: The stereodivergent behavior of allenyl(cyano)- and allenyl(alkyl)cuprates toward aldehydes, providing a selective preparation of both syn- and anti-homopropargylic alcohols, is described. This study, which combines both experimental and theoretical support, shows that the copper nontransferred "dummy ligand" controls the localization of the lithium cation with respect to the allenylcuprate moiety. As a consequence, Li(+) acts as a Lewis acid activator but also controls the diastereoselectivity during the addition of allenylcuprates onto aldehydes. The combined high selectivity, efficiency, and versatility of these cuprate compounds opens the way to new one-pot synthetic procedures, as illustrated by the combined Klein rearrangement/transmetalation methodology described herein.
authors.affiliation: Institut Charles Gerhardt Montpellier, UMR 5253, CNRS-UM2-UM1-ENSCM, 8, rue de l'ôcole Normale, 34296 Montpellier, France. emmanuel.vrancken@enscm.fr
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Vrancken
authors.forename: Hélène
authors.initials: H
authors.lastname: Gérard
authors.forename: David
authors.initials: D
authors.lastname: Linder
authors.forename: Souad
authors.initials: S
authors.lastname: Ouizem
authors.forename: Nacira
authors.initials: N
authors.lastname: Alouane
authors.forename: Eve
authors.initials: E
authors.lastname: Roubineau
authors.forename: Kamel
authors.initials: K
authors.lastname: Bentayeb
authors.forename: Jérôme
authors.initials: J
authors.lastname: Marrot
authors.forename: Pierre
authors.initials: P
authors.lastname: Mangeney