%0 Journal Article
%T NHC Catalysis for Umpolung Pyridinium Alkylation via Deoxy-Breslow Intermediates.
%A Wu T
%A Tatton MR
%A Greaney MF
%J Angew Chem Weinheim Bergstr Ger
%V 134
%N 15
%D 2022 Apr 4
%M 38504766
暂无%R 10.1002/ange.202117524
%X Umpolung N-heterocyclic carbene (NHC) catalysis of non-aldehyde substrates offers new pathways for C-C bond formation, but has proven challenging to develop in terms of viable substrate classes. Here, we demonstrate that pyridinium ions can undergo NHC addition and subsequent intramolecular C-C bond formation through a deoxy-Breslow intermediate. The alkylation demonstrates, for the first time, that deoxy-Breslow intermediates are viable for catalytic umpolung of areniums.<BR>NHC deoxy‐Breslow catalysis offers new umpolung possibilities for electron‐poor arene rings. NHC organocatalysis is largely restricted to aldehydes, with other electrophiles proving difficult to harness. It is shown that a pyridinium system can react successfully with an NHC, enabling intramolecular C−C bond formation with a Michael acceptor through a deoxy‐Breslow intermediate.