Palladium-catalyzed dearomative Heck/[4 + 3] decarboxylative cyclization of indoles with α-oxocarboxylic acids via C–H activation

Herein, we report a novel palladium-catalyzed dearomative Heck/[4 + 3] decarboxylative cyclization of C2-tethered indoles with α-oxocarboxylic acids via C–H activation. In this reaction, dearomatization of C2-tethered indoles occurs via a Heck reaction pathway, leading to the formation of the alkyl-Pd(II) species. Subsequently, this species undergoes C–H activation, rather than the typical nucleophilic trapping or β-H elimination, to generate C,C-palladacycles, which are then captured by α-oxocarboxylic acids to afford hexacyclic and octocyclic fused indolines containing a seven-membered ring.