title: LiCl-effect on asymmetric intramolecular hydroamination catalyzed by binaphthylamido yttrium complexes.
abstract: Chiral alkyl or amido yttrium complexes were prepared from N-silyl- or N-cyclopentyl-substituted binaphthylamido ligands. According to the synthetic procedure, these complexes could be obtained in their neutral form or as heterobimetallic complexes in the presence of 1 equiv. LiCl. These new species were characterized by IR and NMR spectroscopies, elemental analyses and some of them by X-ray diffraction studies. Their efficiency as catalysts for the asymmetric intramolecular hydroamination was then evaluated with several substrates towards the synthesis of two pyrrolidines and a piperidine derivative. A cooperative effect between the lithium and the yttrium atoms was undoubtedly revealed. LiCl-containing complexes afforded indeed higher enantioselectivities than their salt-free counterparts and according to the structure of the chiral ligand, they were also the most active species.
authors.affiliation: Equipe de Catalyse Moléculaire, Univ Paris-Sud, ICMMO, UMR 8182, Orsay, F-91405, France.
authors.forename: Yulia
authors.initials: Y
authors.lastname: Chapurina
authors.forename: Régis
authors.initials: R
authors.lastname: Guillot
authors.forename: Dmitrii
authors.initials: D
authors.lastname: Lyubov
authors.forename: Alexander
authors.initials: A
authors.lastname: Trifonov
authors.forename: Jérôme
authors.initials: J
authors.lastname: Hannedouche
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Schulz