Cu-Catalyzed Direct Asymmetric Mannich Reaction of 2-Alkylazaarenes and Isatin-Derived Ketimines

Org Lett. 2024 Mar 1;26(8):1699-1704. doi: 10.1021/acs.orglett.4c00227. Epub 2024 Feb 22.

Abstract

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.