Pd-Catalyzed Cascade Intramolecular Heck Cyclization/Dearomatization of Indoles for the Construction of Two All-Carbon Quaternary Centers.

A facile Pd-catalyzed cascade of intramolecular Heck cyclization/alkylpalladium activated dearomatization of aryl alkyne-tethered indole is described. In this single step two nonadjacent all-carbon quaternary centers, two nitrogen-containing heterocycles, and three C(sp 2 )-C(sp 3 ) bonds are efficiently furnished. These products could also undergo 5-to-6 ring migration-expansion reaction under Brønsted-acid conditions to transform into the benzo[ c ]carbazole skeletons.