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

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.

Modular and stereoselective synthesis of tetrasubstituted vinyl sulfides leading to a library of AIEgens

“…3 and 4 for more details). Furthermore, this calculation demonstrated that this [1,4]-acyl migration presumably proceeds via a free ylide intermediate, which was consistent with the known [1,4]-acyl migration from O to C 64 .…”

Chemo‐ and Enantioselective Insertion of Furyl Carbene into the N−H Bond of 2‐Pyridones

“…Metal‐carbene mediated alkylation of 2‐pyridones with diazo compounds appears to favor O−H over N−H insertion [3] . To finesse this limitation, we have developed an enantioselective, rhodium‐catalyzed dearomative N‐alkylation of 2‐oxypyridines involving ylide formation and O‐to‐N acyl rearrangement [4] . However, this protocol was also limited in its requirement for donor–acceptor diazoacetates as the alkylation reagents.…”

Chemo‐ and Enantioselective Insertion of Furyl Carbene into the N−H Bond of 2‐Pyridones

“…Unlike 2‐oxypyridines which react with Rh‐carbene only at its N‐site, [4] 2‐pyridone is a more challenging substrate. As shown in Scheme 4 and Figure S1, 2‐pyridone ( Pyr O‐NH ) is more stable than its isomer 2‐hydroxypyridine ( Pyr N‐OH ) and its isomerization is feasible.…”