Access to N‐Substituted 2‐Pyridones by Catalytic Intermolecular Dearomatization and 1,4‐Acyl Transfer

Metal–carbene reaction: A novel rhodium‐catalyzed dearomatization of O‐substituted pyridines provides N‐substituted 2‐pyridones. A computational study suggests a mechanism involving the formation of a pyridinium ylide followed by 1,4‐acyl migratory rearrangement from O to C. When chiral dirhodium complexes serve as the catalyst, the asymmetric variant proceeds with excellent enantioselective control.

Abstract

A novel rhodium‐catalyzed dearomatization of O‐substituted pyridines to access N‐substituted 2‐pyridones has been developed. A computational study suggests a mechanism involving the formation of a pyridinium ylide followed by an unprecedented 1,4‐acyl migratory rearrangement from O to C. Furthermore, the chiral dirhodium complexes serve as the catalyst for the asymmetric transformation with excellent enantioselective control. DFT calculations indicate the chirality is transferred from axial chirality to the central stereogenic centre. The stronger π–π interaction and CH–π interaction account for the high enantioselectivity.

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