PDF(Pubmed)
Abstract：
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.
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.
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.
摘要：
非醛底物的UmpolungN-杂环卡宾（NHC）催化为C-C键形成提供了新的途径，但已证明在可行的底物类别方面具有挑战性。这里,我们证明吡啶离子可以通过脱氧-Breslow中间体进行NHC加成和随后的分子内C-C键形成。烷基化表明，第一次,脱氧-Breslow中间体可用于催化增强芳烃。
NHC脱氧-Breslow催化为低电子芳烃环提供了新的增强可能性。NHC有机催化主要限于醛，与其他亲电试剂证明难以利用。表明吡啶鎓体系可以与NHC成功反应，通过脱氧布雷斯洛中间体，使分子内C-C键与迈克尔受体形成。
NHC脱氧-Breslow催化为低电子芳烃环提供了新的增强可能性。NHC有机催化主要限于醛，与其他亲电试剂证明难以利用。表明吡啶鎓体系可以与NHC成功反应，通过脱氧布雷斯洛中间体，使分子内C-C键与迈克尔受体形成。
