Stereoselective Synthesis of Tetrasubstituted Axially Chiral N ‐Vinylquinolinones via Substrate‐Directed Asymmetric Allylic Substitution‐Isomerization

We report herein an asymmetric allylic substitution-isomerization (AASI) strategy for the synthesis of tetrasubstituted axially chiral N-vinylquinolinones. The stereochemical outcome is critically dependent on the structure of the MBH carbonate precursor. Our studies reveal that MBH carbonates derived from 2-pyridinecarboxaldehyde bearing a methyl ester group are essential for achieving high E-selectivity. In contrast, substitution of the methyl ester with a tert-butyl group leads to a substantial loss of stereocontrol, thereby revealing the latent potential for stereodivergent synthesis of congested axially chiral scaffolds. This method operates under mild conditions, accommodates diverse substrate structures, and provides a practical and efficient route to this important class of axially chiral molecules.