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

Vinylcarbene insertion into the nitrogen-hydrogen (N-H) bond of amines allows direct access to alpha,beta-unsaturated gamma-amino acid derivatives, meeting a marked challenge in the control of regio- and enantioselectivities. Here, we report a highly gamma-selective and enantioselective insertion into N-H bonds of aliphatic or aromatic secondary amines with vinyl substituted alpha-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 gamma-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.

Automated summary

In this study, a novel method was developed for the synthesis of vinyl gamma-amino amides with high gamma-selectivity and enantioselectivity using a high-spin chiral complex catalyst. The calculation showed a spin state change from quartet cobalt(II) complex to doublet Co(II)-carbene species for Z-selective and enantioselective nucleophilic addition.