A novel
palladium-catalyzed decarboxylative cascade cyclization
for the assembly of diverse fused heteropolycycles by employing α-oxocarboxylic
acids as three-carbon insertion units is reported. This protocol enables
the synthesis of isoquinolinedione- and indolo[2,1-a]isoquinolinone-fused benzocycloheptanones in moderate to good yields
by the use of different aryl iodides, including alkene-tethered 2-iodobenzamides
and 2-(2-iodophenyl)-1H-indoles. Notably, the approach
achieves simultaneous construction of both six- and seven-membered
rings via sequential intramolecular carbopalladation, C–H activation,
and decarboxylation.