N-Heterocyclic-Carbene-Catalyzed Synthesis of 2-Aryl Indoles

A convergent and efficient transition‐metal‐free catalytic synthesis of 2‐aryl‐indoles has been developed. The interception of a highly reactive and transient aza‐ortho‐quinone methide by an acyl anion equivalent generated through N‐hetereocyclic carbene catalysis is central to this successful strategy. High yields and a wide scope as well as the streamlined synthesis of a kinase inhibitor are reported. Umpolung: N‐heterocyclic carbene catalysis is used for the convergent and efficient transition‐metal‐free synthesis of 2‐aryl‐indoles. The interception of a highly reactive and transient aza‐ortho‐quinone methide by an acyl anion equivalent is central to this successful strategy. The reaction exhibits high yields and a wide scope, and it has been applied to a streamlined synthesis of a kinase inhibitor.