title: Application of monodentate secondary phosphine oxides, a new class of chiral ligands, in Ir(i)-catalyzed asymmetric imine hydrogenation.
abstract: Secondary phosphine oxides were prepared from R(1)PCl(2) and R(2)MgBr, followed by hydrolysis. They were obtained in an enantiopure form by preparative chiral HPLC. These new monodentate ligands were tested in the iridium-catalyzed hydrogenation of imines at 25 bar. Enantioselectivities up to 76% were obtained at L/Ir = 2. Addition of pyridine (Pyr/Ir = 1:2) raised the ee to 83%. Using pyridine as an additive allowed reduction of the L/Ir ratio to 1 without reduction of ee. [reaction: see text]
authors.affiliation: Department of Organic and Molecular Inorganic Chemistry, Stratingh Institute, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands.
authors.forename: Xiao-Bin
authors.initials: XB
authors.lastname: Jiang
authors.forename: Adriaan J
authors.initials: AJ
authors.lastname: Minnaard
authors.forename: Bart
authors.initials: B
authors.lastname: Hessen
authors.forename: Ben L
authors.initials: BL
authors.lastname: Feringa
authors.forename: Alexander L L
authors.initials: AL
authors.lastname: Duchateau
authors.forename: Jean G O
authors.initials: JG
authors.lastname: Andrien
authors.forename: Jeroen A F
authors.initials: JA
authors.lastname: Boogers
authors.forename: Johannes G
authors.initials: JG
authors.lastname: de Vries