Lanthanide complexes coordinated by N-substituted (R)-1,1′-binaphthyl-2,2′-diamido ligands in the catalysis of enantioselective intramolecular hydroamination

A new family of lanthanide ionic complexes derived from chiral, substituted (R)-binaphthylamine ligands, [Li(thf)(4)][Ln{(R)-C20H12(NR)(2)}(2)] (Ln=Yb, Sm, Nd, or Lu), has been synthesized and characterized by X-ray crystal structure analyses. All complexes have been tested as new catalysts for the hydroamination/cyclization of 1-(aminomethyl)-1-allylcyclohexane. Ytterbium complexes proved to be both the most active and the most enantioselective, and the use of the complex [Li(thf)(4)][Yb{(R)-C20H12-(NC3H7)(2)}(2)], bearing isopropyl radicals on the nitrogen atoms, allowed the formation of the corresponding spiropyrrolidine in high yield with up to 70% ee.