Asymmetric hydroamination catalyzed by in situ generated chiral amidate and ureate complexes of zirconium--probing the role of the tether in ligand design

Simple chiral proligands have been synthesized from inexpensive chiral starting materials. These amidate and ureate ligands support zirconium complexes that successfully catalyze intramolecular hydroamination with up to 26% ee. Several elements necessary for successful ligand design are highlighted and discussed. In particular, the strict control of metal geometry through multidentate tethered ligands is determined to be an essential aspect of future ligand development. Key words: ureate, amidate, hydroamination, zirconium, enantioselective. On a realise la synthese de proligands chiraux simples a partir de produits de depart chiraux peu couteux. Ces ligands amidates et ureates supportent des complexes du zirconium qui peut catalyseur avec succes des hydroaminations intramoleculaires avec des exces d'enantiomere allant jusqu'a 26 %. On met en evidence et on discute de plusieurs elements necessaires au bon developpement d'un ligand. En particulier, on a determine qu'un aspect essentiel du developpement du futur ligand est le controle strict de la geometrie du metal par le biais de ligands multidentates bien fixes, Mots-cles : ureate, amidate, hydroamination, zirconium, enantioselective. [Traduit par la Redaction]
Introduction Hydroamination, the addition of an N-H bond across unsaturated C-C bonds, has shown great promise for the efficient synthesis of amines. (1) Numerous systems exist for this highly desirable [...]