Catalytic, Enantioselective Intramolecular Hydroamination of Primary Amines Tethered to Di- and Trisubstituted Alkenes

The in situ preparation of chiral amido alkyl ate yttrium
complexes
from an array of chiral N-benzyl-like-substituted
binaphthyldiamines is reported. These chiral heteroleptic complexes
are shown to be efficient catalysts for the enantioselective intramolecular
hydroamination of primary amines tethered to sterically demanding
alkenes at high reaction temperatures. Fine tuning of their chiral
environment allowed up to 77% ee to be reached for the cyclization
of aminoalkenes bearing 1,2-dialkyl-substituted carbon–carbon
double bonds. These chiral complexes also demonstrate the ability
to promote the cyclization of amine-tethered trisubstituted alkenes
in up to 55% ee, as the first report of the formation of enantioenriched
quaternary centers by an hydroamination reaction.