The
first direct catalytic asymmetric Mannich reaction
of 2-alkylazaarenes
and ketimines was realized with a chiral Cu–bis(oxazoline)
complex as the catalyst. The asymmetric addition of 2-alkylpyridines
to isatin-derived ketimines proceeded smoothly to afford α,β-functionalized
2-substituted pyridines bearing 3-amino-3,3-disubstituted oxindole
motifs with excellent results (≤99% yield, 99:1 dr, and 98%
ee). The catalytic system was also extended to 2-alkylbenzothiazoles
as nucleophiles for the asymmetric Mannich reaction of ketimines.