title: Rhodium-Catalyzed Asymmetric Conjugate Additions of Boronic Acids to enones using DIPHONANE: a novel chiral bisphosphine ligand.
abstract: [reaction: see text] The synthesis of a novel enantiopure C2-symmetric bisphosphine, DIPHONANE, was accomplished starting from 2,5-norbornadione, utilizing (R,R)- and/or (S,S)-(2,3-O-di[(phenylamino)carbonyl]tartaric acid for the resolution of an intermediate phosphineoxide. The application of this ligand in the rhodium-catalyzed asymmetric conjugate addition of boronic acids to cyclic enones provides the 1,4-addition products in good yields (69-98%) and high ee's (78-95% ee). A byproduct arising from a consecutive 1,4-addition and 1,2-addition was also observed.
authors.affiliation: Laboratory for Organic and Bioorganic Synthesis, Department of Organic Chemistry, Ghent University, Krijgslaan 281 (S.4), B-9000 Gent, Belgium.
authors.forename: Koen
authors.initials: K
authors.lastname: Vandyck
authors.forename: Bavo
authors.initials: B
authors.lastname: Matthys
authors.forename: Mario
authors.initials: M
authors.lastname: Willen
authors.forename: Koen
authors.initials: K
authors.lastname: Robeyns
authors.forename: Luc
authors.initials: L
authors.lastname: Van Meervelt
authors.forename: Johan
authors.initials: J
authors.lastname: Van der Eycken