Enantioselective Formal Vinylogous N-H Insertion of Secondary Aliphatic Amines Catalyzed by a High-Spin Cobalt(II) Complex

J Am Chem Soc. 2021 Jun 30;143(25):9648-9656. doi: 10.1021/jacs.1c04367. Epub 2021 Jun 21.

Abstract

Vinylcarbene insertion into the nitrogen-hydrogen (N-H) bond of amines allows direct access to α,β-unsaturated γ-amino acid derivatives, meeting a marked challenge in the control of regio- and enantioselectivities. Here, we report a highly γ-selective and enantioselective insertion into N-H bonds of aliphatic or aromatic secondary amines with vinyl substituted α-diazo pyrazoleamides using a high-spin chiral N,N'-dioxide/cobalt(II) complex catalyst. The method affords a wide variety of valuable optically active Z- and E-type vinyl γ-amino amides. Calculation reveals a spin state change from the quartet cobalt(II) complex to a doublet Co(II)-carbene species for facile Z-selective and enantioselective nucleophilic addition.

Publication types

  • Research Support, Non-U.S. Gov't